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path: root/arch/x86/kvm/svm/sev.c
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2023-09-23KVM: SVM: Fix TSC_AUX virtualization setupTom Lendacky
The checks for virtualizing TSC_AUX occur during the vCPU reset processing path. However, at the time of initial vCPU reset processing, when the vCPU is first created, not all of the guest CPUID information has been set. In this case the RDTSCP and RDPID feature support for the guest is not in place and so TSC_AUX virtualization is not established. This continues for each vCPU created for the guest. On the first boot of an AP, vCPU reset processing is executed as a result of an APIC INIT event, this time with all of the guest CPUID information set, resulting in TSC_AUX virtualization being enabled, but only for the APs. The BSP always sees a TSC_AUX value of 0 which probably went unnoticed because, at least for Linux, the BSP TSC_AUX value is 0. Move the TSC_AUX virtualization enablement out of the init_vmcb() path and into the vcpu_after_set_cpuid() path to allow for proper initialization of the support after the guest CPUID information has been set. With the TSC_AUX virtualization support now in the vcpu_set_after_cpuid() path, the intercepts must be either cleared or set based on the guest CPUID input. Fixes: 296d5a17e793 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts") Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Message-Id: <4137fbcb9008951ab5f0befa74a0399d2cce809a.1694811272.git.thomas.lendacky@amd.com> Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-09-23KVM: SVM: INTERCEPT_RDTSCP is never intercepted anywayPaolo Bonzini
svm_recalc_instruction_intercepts() is always called at least once before the vCPU is started, so the setting or clearing of the RDTSCP intercept can be dropped from the TSC_AUX virtualization support. Extracted from a patch by Tom Lendacky. Cc: stable@vger.kernel.org Fixes: 296d5a17e793 ("KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX intercepts") Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-31Merge tag 'kvm-x86-svm-6.6' of https://github.com/kvm-x86/linux into HEADPaolo Bonzini
KVM: x86: SVM changes for 6.6: - Add support for SEV-ES DebugSwap, i.e. allow SEV-ES guests to use debug registers and generate/handle #DBs - Clean up LBR virtualization code - Fix a bug where KVM fails to set the target pCPU during an IRTE update - Fix fatal bugs in SEV-ES intrahost migration - Fix a bug where the recent (architecturally correct) change to reinject #BP and skip INT3 broke SEV guests (can't decode INT3 to skip it)
2023-08-25KVM: SVM: Require nrips support for SEV guests (and beyond)Sean Christopherson
Disallow SEV (and beyond) if nrips is disabled via module param, as KVM can't read guest memory to partially emulate and skip an instruction. All CPUs that support SEV support NRIPS, i.e. this is purely stopping the user from shooting themselves in the foot. Cc: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230825013621.2845700-3-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-25KVM: SVM: Skip VMSA init in sev_es_init_vmcb() if pointer is NULLSean Christopherson
Skip initializing the VMSA physical address in the VMCB if the VMSA is NULL, which occurs during intrahost migration as KVM initializes the VMCB before copying over state from the source to the destination (including the VMSA and its physical address). In normal builds, __pa() is just math, so the bug isn't fatal, but with CONFIG_DEBUG_VIRTUAL=y, the validity of the virtual address is verified and passing in NULL will make the kernel unhappy. Fixes: 6defa24d3b12 ("KVM: SEV: Init target VMCBs in sev_migrate_from") Cc: stable@vger.kernel.org Cc: Peter Gonda <pgonda@google.com> Reviewed-by: Peter Gonda <pgonda@google.com> Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com> Link: https://lore.kernel.org/r/20230825022357.2852133-3-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-25KVM: SVM: Get source vCPUs from source VM for SEV-ES intrahost migrationSean Christopherson
Fix a goof where KVM tries to grab source vCPUs from the destination VM when doing intrahost migration. Grabbing the wrong vCPU not only hoses the guest, it also crashes the host due to the VMSA pointer being left NULL. BUG: unable to handle page fault for address: ffffe38687000000 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP NOPTI CPU: 39 PID: 17143 Comm: sev_migrate_tes Tainted: GO 6.5.0-smp--fff2e47e6c3b-next #151 Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 34.28.0 07/10/2023 RIP: 0010:__free_pages+0x15/0xd0 RSP: 0018:ffff923fcf6e3c78 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffe38687000000 RCX: 0000000000000100 RDX: 0000000000000100 RSI: 0000000000000000 RDI: ffffe38687000000 RBP: ffff923fcf6e3c88 R08: ffff923fcafb0000 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff83619b90 R12: ffff923fa9540000 R13: 0000000000080007 R14: ffff923f6d35d000 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff929d0d7c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffe38687000000 CR3: 0000005224c34005 CR4: 0000000000770ee0 PKRU: 55555554 Call Trace: <TASK> sev_free_vcpu+0xcb/0x110 [kvm_amd] svm_vcpu_free+0x75/0xf0 [kvm_amd] kvm_arch_vcpu_destroy+0x36/0x140 [kvm] kvm_destroy_vcpus+0x67/0x100 [kvm] kvm_arch_destroy_vm+0x161/0x1d0 [kvm] kvm_put_kvm+0x276/0x560 [kvm] kvm_vm_release+0x25/0x30 [kvm] __fput+0x106/0x280 ____fput+0x12/0x20 task_work_run+0x86/0xb0 do_exit+0x2e3/0x9c0 do_group_exit+0xb1/0xc0 __x64_sys_exit_group+0x1b/0x20 do_syscall_64+0x41/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> CR2: ffffe38687000000 Fixes: 6defa24d3b12 ("KVM: SEV: Init target VMCBs in sev_migrate_from") Cc: stable@vger.kernel.org Cc: Peter Gonda <pgonda@google.com> Reviewed-by: Peter Gonda <pgonda@google.com> Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com> Link: https://lore.kernel.org/r/20230825022357.2852133-2-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-08-04KVM: SEV: remove ghcb variable declarationsPaolo Bonzini
To avoid possible time-of-check/time-of-use issues, the GHCB should almost never be accessed outside dump_ghcb, sev_es_sync_to_ghcb and sev_es_sync_from_ghcb. The only legitimate uses are to set the exitinfo fields and to find the address of the scratch area embedded in the ghcb. Accessing ghcb_usage also goes through svm->sev_es.ghcb in sev_es_validate_vmgexit(), but that is because anyway the value is not used. Removing a shortcut variable that contains the value of svm->sev_es.ghcb makes these cases a bit more verbose, but it limits the chance of someone reading the ghcb by mistake. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-04KVM: SEV: only access GHCB fields oncePaolo Bonzini
A KVM guest using SEV-ES or SEV-SNP with multiple vCPUs can trigger a double fetch race condition vulnerability and invoke the VMGEXIT handler recursively. sev_handle_vmgexit() maps the GHCB page using kvm_vcpu_map() and then fetches the exit code using ghcb_get_sw_exit_code(). Soon after, sev_es_validate_vmgexit() fetches the exit code again. Since the GHCB page is shared with the guest, the guest is able to quickly swap the values with another vCPU and hence bypass the validation. One vmexit code that can be rejected by sev_es_validate_vmgexit() is SVM_EXIT_VMGEXIT; if sev_handle_vmgexit() observes it in the second fetch, the call to svm_invoke_exit_handler() will invoke sev_handle_vmgexit() again recursively. To avoid the race, always fetch the GHCB data from the places where sev_es_sync_from_ghcb stores it. Exploiting recursions on linux kernel has been proven feasible in the past, but the impact is mitigated by stack guard pages (CONFIG_VMAP_STACK). Still, if an attacker manages to call the handler multiple times, they can theoretically trigger a stack overflow and cause a denial-of-service, or potentially guest-to-host escape in kernel configurations without stack guard pages. Note that winning the race reliably in every iteration is very tricky due to the very tight window of the fetches; depending on the compiler settings, they are often consecutive because of optimization and inlining. Tested by booting an SEV-ES RHEL9 guest. Fixes: CVE-2023-4155 Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Cc: stable@vger.kernel.org Reported-by: Andy Nguyen <theflow@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-08-04KVM: SEV: snapshot the GHCB before accessing itPaolo Bonzini
Validation of the GHCB is susceptible to time-of-check/time-of-use vulnerabilities. To avoid them, we would like to always snapshot the fields that are read in sev_es_validate_vmgexit(), and not use the GHCB anymore after it returns. This means: - invoking sev_es_sync_from_ghcb() before any GHCB access, including before sev_es_validate_vmgexit() - snapshotting all fields including the valid bitmap and the sw_scratch field, which are currently not caching anywhere. The valid bitmap is the first thing to be copied out of the GHCB; then, further accesses will use the copy in svm->sev_es. Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2023-07-28KVM: SVM: Don't defer NMI unblocking until next exit for SEV-ES guestsSean Christopherson
Immediately mark NMIs as unmasked in response to #VMGEXIT(NMI complete) instead of setting awaiting_iret_completion and waiting until the *next* VM-Exit to unmask NMIs. The whole point of "NMI complete" is that the guest is responsible for telling the hypervisor when it's safe to inject an NMI, i.e. there's no need to wait. And because there's no IRET to single-step, the next VM-Exit could be a long time coming, i.e. KVM could incorrectly hold an NMI pending for far longer than what is required and expected. Opportunistically fix a stale reference to HF_IRET_MASK. Fixes: 916b54a7688b ("KVM: x86: Move HF_NMI_MASK and HF_IRET_MASK into "struct vcpu_svm"") Fixes: 4444dfe4050b ("KVM: SVM: Add NMI support for an SEV-ES guest") Cc: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-9-aik@amd.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SEV-ES: Eliminate #DB intercept when DebugSwap enabledAlexey Kardashevskiy
Disable #DB for SEV-ES guests when DebugSwap is enabled. There is no point in such intercept as KVM does not allow guest debug for SEV-ES guests. Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-8-aik@amd.com [sean: add comment as to why KVM disables #DB intercept iff DebugSwap=1] Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SEV: Enable data breakpoints in SEV-ESAlexey Kardashevskiy
Add support for "DebugSwap for SEV-ES guests", which provides support for swapping DR[0-3] and DR[0-3]_ADDR_MASK on VMRUN and VMEXIT, i.e. allows KVM to expose debug capabilities to SEV-ES guests. Without DebugSwap support, the CPU doesn't save/load most _guest_ debug registers (except DR6/7), and KVM cannot manually context switch guest DRs due the VMSA being encrypted. Enable DebugSwap if and only if the CPU also supports NoNestedDataBp, which causes the CPU to ignore nested #DBs, i.e. #DBs that occur when vectoring a #DB. Without NoNestedDataBp, a malicious guest can DoS the host by putting the CPU into an infinite loop of vectoring #DBs (see https://bugzilla.redhat.com/show_bug.cgi?id=1278496) Set the features bit in sev_es_sync_vmsa() which is the last point when VMSA is not encrypted yet as sev_(es_)init_vmcb() (where the most init happens) is called not only when VCPU is initialised but also on intrahost migration when VMSA is encrypted. Eliminate DR7 intercepts as KVM can't modify guest DR7, and intercepting DR7 would completely defeat the purpose of enabling DebugSwap. Make X86_FEATURE_DEBUG_SWAP appear in /proc/cpuinfo (by not adding "") to let the operator know if the VM can debug. Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-7-aik@amd.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SVM/SEV/SEV-ES: Rework interceptsAlexey Kardashevskiy
Currently SVM setup is done sequentially in init_vmcb() -> sev_init_vmcb() -> sev_es_init_vmcb() and tries keeping SVM/SEV/SEV-ES bits separated. One of the exceptions is DR intercepts which is for SEV-ES before sev_es_init_vmcb() runs. Move the SEV-ES intercept setup to sev_es_init_vmcb(). From now on set_dr_intercepts()/clr_dr_intercepts() handle SVM/SEV only. No functional change intended. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Reviewed-by: Santosh Shukla <santosh.shukla@amd.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-6-aik@amd.com [sean: drop comment about intercepting DR7] Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SEV-ES: explicitly disable debugAlexey Kardashevskiy
SVM/SEV enable debug registers intercepts to skip swapping DRs on entering/exiting the guest. When the guest is in control of debug registers (vcpu->guest_debug == 0), there is an optimisation to reduce the number of context switches: intercepts are cleared and the KVM_DEBUGREG_WONT_EXIT flag is set to tell KVM to do swapping on guest enter/exit. The same code also executes for SEV-ES, however it has no effect as - it always takes (vcpu->guest_debug == 0) branch; - KVM_DEBUGREG_WONT_EXIT is set but DR7 intercept is not cleared; - vcpu_enter_guest() writes DRs but VMRUN for SEV-ES swaps them with the values from _encrypted_ VMSA. Be explicit about SEV-ES not supporting debug: - return right away from dr_interception() and skip unnecessary processing; - return an error right away from the KVM_SEV_LAUNCH_UPDATE_VMSA handler if debugging was already enabled. KVM_SET_GUEST_DEBUG are failing already after KVM_SEV_LAUNCH_UPDATE_VMSA is finished due to vcpu->arch.guest_state_protected set to true. Add WARN_ON to kvm_x86::sync_dirty_debug_regs() (saves guest DRs on guest exit) to signify that SEV-ES won't hit that path. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-5-aik@amd.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SVM: Rewrite sev_es_prepare_switch_to_guest()'s comment about swap typesSean Christopherson
Rewrite the comment(s) in sev_es_prepare_switch_to_guest() to explain the swap types employed by the CPU for SEV-ES guests, i.e. to explain why KVM needs to save a seemingly random subset of host state, and to provide a decoder for the APM's Type-A/B/C terminology. Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-4-aik@amd.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-07-28KVM: SEV: Move SEV's GP_VECTOR intercept setup to SEVAlexey Kardashevskiy
Currently SVM setup is done sequentially in init_vmcb() -> sev_init_vmcb() -> sev_es_init_vmcb() and tries keeping SVM/SEV/SEV-ES bits separated. One of the exceptions is #GP intercept which init_vmcb() skips setting for SEV guests and then sev_es_init_vmcb() needlessly clears it. Remove the SEV check from init_vmcb(). Clear the #GP intercept in sev_init_vmcb(). SEV-ES will use the SEV setting. No functional change intended. Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Alexey Kardashevskiy <aik@amd.com> Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Reviewed-by: Santosh Shukla <santosh.shukla@amd.com> Link: https://lore.kernel.org/r/20230615063757.3039121-3-aik@amd.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-06-13KVM: SVM: WARN, but continue, if misc_cg_set_capacity() failsSean Christopherson
WARN and continue if misc_cg_set_capacity() fails, as the only scenario in which it can fail is if the specified resource is invalid, which should never happen when CONFIG_KVM_AMD_SEV=y. Deliberately not bailing "fixes" a theoretical bug where KVM would leak the ASID bitmaps on failure, which again can't happen. If the impossible should happen, the end result is effectively the same with respect to SEV and SEV-ES (they are unusable), while continuing on has the advantage of letting KVM load, i.e. userspace can still run non-SEV guests. Reported-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Link: https://lore.kernel.org/r/20230607004449.1421131-1-seanjc@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-06-06KVM: SVM: enhance info printk's in SEV initAlexander Mikhalitsyn
Let's print available ASID ranges for SEV/SEV-ES guests. This information can be useful for system administrator to debug if SEV/SEV-ES fails to enable. There are a few reasons. SEV: - NPT is disabled (module parameter) - CPU lacks some features (sev, decodeassists) - Maximum SEV ASID is 0 SEV-ES: - mmio_caching is disabled (module parameter) - CPU lacks sev_es feature - Minimum SEV ASID value is 1 (can be adjusted in BIOS/UEFI) Cc: Sean Christopherson <seanjc@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Stéphane Graber <stgraber@ubuntu.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Suggested-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> Link: https://lore.kernel.org/r/20230522161249.800829-3-aleksandr.mikhalitsyn@canonical.com [sean: print '0' for min SEV-ES ASID if there are no available ASIDs] Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-04-26Merge tag 'v6.4-p1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 Pull crypto updates from Herbert Xu: "API: - Total usage stats now include all that returned errors (instead of just some) - Remove maximum hash statesize limit - Add cloning support for hmac and unkeyed hashes - Demote BUG_ON in crypto_unregister_alg to a WARN_ON Algorithms: - Use RIP-relative addressing on x86 to prepare for PIE build - Add accelerated AES/GCM stitched implementation on powerpc P10 - Add some test vectors for cmac(camellia) - Remove failure case where jent is unavailable outside of FIPS mode in drbg - Add permanent and intermittent health error checks in jitter RNG Drivers: - Add support for 402xx devices in qat - Add support for HiSTB TRNG - Fix hash concurrency issues in stm32 - Add OP-TEE firmware support in caam" * tag 'v6.4-p1' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (139 commits) i2c: designware: Add doorbell support for Mendocino i2c: designware: Use PCI PSP driver for communication powerpc: Move Power10 feature PPC_MODULE_FEATURE_P10 crypto: p10-aes-gcm - Remove POWER10_CPU dependency crypto: testmgr - Add some test vectors for cmac(camellia) crypto: cryptd - Add support for cloning hashes crypto: cryptd - Convert hash to use modern init_tfm/exit_tfm crypto: hmac - Add support for cloning crypto: hash - Add crypto_clone_ahash/shash crypto: api - Add crypto_clone_tfm crypto: api - Add crypto_tfm_get crypto: x86/sha - Use local .L symbols for code crypto: x86/crc32 - Use local .L symbols for code crypto: x86/aesni - Use local .L symbols for code crypto: x86/sha256 - Use RIP-relative addressing crypto: x86/ghash - Use RIP-relative addressing crypto: x86/des3 - Use RIP-relative addressing crypto: x86/crc32c - Use RIP-relative addressing crypto: x86/cast6 - Use RIP-relative addressing crypto: x86/cast5 - Use RIP-relative addressing ...
2023-04-20SVM-SEV: convert the rest of fget() uses to fdget() in thereAl Viro
Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2023-03-17crypto: ccp - Add a header for multiple drivers to use `__psp_pa`Mario Limonciello
The TEE subdriver for CCP, the amdtee driver and the i2c-designware-amdpsp drivers all include `psp-sev.h` even though they don't use SEV functionality. Move the definition of `__psp_pa` into a common header to be included by all of these drivers. Reviewed-by: Jan Dabros <jsd@semihalf.com> Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com> # For the drivers/i2c/busses/i2c-designware-amdpsp.c Acked-by: Sumit Garg <sumit.garg@linaro.org> # For TEE subsystem bits Acked-by: Tom Lendacky <thomas.lendacky@amd.com> Acked-by: Sean Christopherson <seanjc@google.com> # KVM Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2023-02-07KVM: SVM: Fix potential overflow in SEV's send|receive_update_data()Peter Gonda
KVM_SEV_SEND_UPDATE_DATA and KVM_SEV_RECEIVE_UPDATE_DATA have an integer overflow issue. Params.guest_len and offset are both 32 bits wide, with a large params.guest_len the check to confirm a page boundary is not crossed can falsely pass: /* Check if we are crossing the page boundary * offset = params.guest_uaddr & (PAGE_SIZE - 1); if ((params.guest_len + offset > PAGE_SIZE)) Add an additional check to confirm that params.guest_len itself is not greater than PAGE_SIZE. Note, this isn't a security concern as overflow can happen if and only if params.guest_len is greater than 0xfffff000, and the FW spec says these commands fail with lengths greater than 16KB, i.e. the PSP will detect KVM's goof. Fixes: 15fb7de1a7f5 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command") Fixes: d3d1af85e2c7 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command") Reported-by: Andy Nguyen <theflow@google.com> Suggested-by: Thomas Lendacky <thomas.lendacky@amd.com> Signed-off-by: Peter Gonda <pgonda@google.com> Cc: David Rientjes <rientjes@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <seanjc@google.com> Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> Link: https://lore.kernel.org/r/20230207171354.4012821-1-pgonda@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2023-01-24KVM: SVM: Account scratch allocations used to decrypt SEV guest memoryAnish Ghulati
Account the temp/scratch allocation used to decrypt unaligned debug accesses to SEV guest memory, the allocation is very much tied to the target VM. Reported-by: Mingwei Zhang <mizhang@google.com> Signed-off-by: Anish Ghulati <aghulati@google.com> Link: https://lore.kernel.org/r/20230113220923.2834699-1-aghulati@google.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2022-12-29KVM: x86: Unify pr_fmt to use module name for all KVM modulesSean Christopherson
Define pr_fmt using KBUILD_MODNAME for all KVM x86 code so that printks use consistent formatting across common x86, Intel, and AMD code. In addition to providing consistent print formatting, using KBUILD_MODNAME, e.g. kvm_amd and kvm_intel, allows referencing SVM and VMX (and SEV and SGX and ...) as technologies without generating weird messages, and without causing naming conflicts with other kernel code, e.g. "SEV: ", "tdx: ", "sgx: " etc.. are all used by the kernel for non-KVM subsystems. Opportunistically move away from printk() for prints that need to be modified anyways, e.g. to drop a manual "kvm: " prefix. Opportunistically convert a few SGX WARNs that are similarly modified to WARN_ONCE; in the very unlikely event that the WARNs fire, odds are good that they would fire repeatedly and spam the kernel log without providing unique information in each print. Note, defining pr_fmt yields undesirable results for code that uses KVM's printk wrappers, e.g. vcpu_unimpl(). But, that's a pre-existing problem as SVM/kvm_amd already defines a pr_fmt, and thankfully use of KVM's wrappers is relatively limited in KVM x86 code. Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Paul Durrant <paul@xen.org> Message-Id: <20221130230934.1014142-35-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-30KVM: SVM: Replace kmap_atomic() with kmap_local_page()Zhao Liu
The use of kmap_atomic() is being deprecated in favor of kmap_local_page()[1]. The main difference between atomic and local mappings is that local mappings don't disable page faults or preemption. There're 2 reasons we can use kmap_local_page() here: 1. SEV is 64-bit only and kmap_local_page() doesn't disable migration in this case, but here the function clflush_cache_range() uses CLFLUSHOPT instruction to flush, and on x86 CLFLUSHOPT is not CPU-local and flushes the page out of the entire cache hierarchy on all CPUs (APM volume 3, chapter 3, CLFLUSHOPT). So there's no need to disable preemption to ensure CPU-local. 2. clflush_cache_range() doesn't need to disable pagefault and the mapping is still valid even if sleeps. This is also true for sched out/in when preempted. In addition, though kmap_local_page() is a thin wrapper around page_address() on 64-bit, kmap_local_page() should still be used here in preference to page_address() since page_address() isn't suitable to be used in a generic function (like sev_clflush_pages()) where the page passed in is not easy to determine the source of allocation. Keeping the kmap* API in place means it can be used for things other than highmem mappings[2]. Therefore, sev_clflush_pages() is a function that should use kmap_local_page() in place of kmap_atomic(). Convert the calls of kmap_atomic() / kunmap_atomic() to kmap_local_page() / kunmap_local(). [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com [2]: https://lore.kernel.org/lkml/5d667258-b58b-3d28-3609-e7914c99b31b@intel.com/ Suggested-by: Dave Hansen <dave.hansen@intel.com> Suggested-by: Ira Weiny <ira.weiny@intel.com> Suggested-by: Fabio M. De Francesco <fmdefrancesco@gmail.com> Signed-off-by: Zhao Liu <zhao1.liu@intel.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20220928092748.463631-1-zhao1.liu@linux.intel.com Signed-off-by: Sean Christopherson <seanjc@google.com>
2022-11-09KVM: SVM: Name and check reserved fields with structs offsetCarlos Bilbao
Rename reserved fields on all structs in arch/x86/include/asm/svm.h following their offset within the structs. Include compile time checks for this in the same place where other BUILD_BUG_ON for the structs are. This also solves that fields of struct sev_es_save_area are named by their order of appearance, but right now they jump from reserved_5 to reserved_7. Link: https://lkml.org/lkml/2022/10/22/376 Signed-off-by: Carlos Bilbao <carlos.bilbao@amd.com> Message-Id: <20221024164448.203351-1-carlos.bilbao@amd.com> [Use ASSERT_STRUCT_OFFSET + fix a couple wrong offsets. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-09KVM: SVM: Only dump VMSA to klog at KERN_DEBUG levelPeter Gonda
Explicitly print the VMSA dump at KERN_DEBUG log level, KERN_CONT uses KERNEL_DEFAULT if the previous log line has a newline, i.e. if there's nothing to continuing, and as a result the VMSA gets dumped when it shouldn't. The KERN_CONT documentation says it defaults back to KERNL_DEFAULT if the previous log line has a newline. So switch from KERN_CONT to print_hex_dump_debug(). Jarkko pointed this out in reference to the original patch. See: https://lore.kernel.org/all/YuPMeWX4uuR1Tz3M@kernel.org/ print_hex_dump(KERN_DEBUG, ...) was pointed out there, but print_hex_dump_debug() should similar. Fixes: 6fac42f127b8 ("KVM: SVM: Dump Virtual Machine Save Area (VMSA) to klog") Signed-off-by: Peter Gonda <pgonda@google.com> Reviewed-by: Sean Christopherson <seanjc@google.com> Cc: Jarkko Sakkinen <jarkko@kernel.org> Cc: Harald Hoyer <harald@profian.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org Message-Id: <20221104142220.469452-1-pgonda@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-11-09KVM: SVM: do not allocate struct svm_cpu_data dynamicallyPaolo Bonzini
The svm_data percpu variable is a pointer, but it is allocated via svm_hardware_setup() when KVM is loaded. Unlike hardware_enable() this means that it is never NULL for the whole lifetime of KVM, and static allocation does not waste any memory compared to the status quo. It is also more efficient and more easily handled from assembly code, so do it and don't look back. Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-08-10KVM: SVM: Disable SEV-ES support if MMIO caching is disableSean Christopherson
Disable SEV-ES if MMIO caching is disabled as SEV-ES relies on MMIO SPTEs generating #NPF(RSVD), which are reflected by the CPU into the guest as a #VC. With SEV-ES, the untrusted host, a.k.a. KVM, doesn't have access to the guest instruction stream or register state and so can't directly emulate in response to a #NPF on an emulated MMIO GPA. Disabling MMIO caching means guest accesses to emulated MMIO ranges cause #NPF(!PRESENT), and those flavors of #NPF cause automatic VM-Exits, not #VC. Adjust KVM's MMIO masks to account for the C-bit location prior to doing SEV(-ES) setup, and document that dependency between adjusting the MMIO SPTE mask and SEV(-ES) setup. Fixes: b09763da4dd8 ("KVM: x86/mmu: Add module param to disable MMIO caching (for testing)") Reported-by: Michael Roth <michael.roth@amd.com> Tested-by: Michael Roth <michael.roth@amd.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220803224957.1285926-4-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-08-01Merge remote-tracking branch 'kvm/next' into kvm-next-5.20Paolo Bonzini
KVM/s390, KVM/x86 and common infrastructure changes for 5.20 x86: * Permit guests to ignore single-bit ECC errors * Fix races in gfn->pfn cache refresh; do not pin pages tracked by the cache * Intel IPI virtualization * Allow getting/setting pending triple fault with KVM_GET/SET_VCPU_EVENTS * PEBS virtualization * Simplify PMU emulation by just using PERF_TYPE_RAW events * More accurate event reinjection on SVM (avoid retrying instructions) * Allow getting/setting the state of the speaker port data bit * Refuse starting the kvm-intel module if VM-Entry/VM-Exit controls are inconsistent * "Notify" VM exit (detect microarchitectural hangs) for Intel * Cleanups for MCE MSR emulation s390: * add an interface to provide a hypervisor dump for secure guests * improve selftests to use TAP interface * enable interpretive execution of zPCI instructions (for PCI passthrough) * First part of deferred teardown * CPU Topology * PV attestation * Minor fixes Generic: * new selftests API using struct kvm_vcpu instead of a (vm, id) tuple x86: * Use try_cmpxchg64 instead of cmpxchg64 * Bugfixes * Ignore benign host accesses to PMU MSRs when PMU is disabled * Allow disabling KVM's "MONITOR/MWAIT are NOPs!" behavior * x86/MMU: Allow NX huge pages to be disabled on a per-vm basis * Port eager page splitting to shadow MMU as well * Enable CMCI capability by default and handle injected UCNA errors * Expose pid of vcpu threads in debugfs * x2AVIC support for AMD * cleanup PIO emulation * Fixes for LLDT/LTR emulation * Don't require refcounted "struct page" to create huge SPTEs x86 cleanups: * Use separate namespaces for guest PTEs and shadow PTEs bitmasks * PIO emulation * Reorganize rmap API, mostly around rmap destruction * Do not workaround very old KVM bugs for L0 that runs with nesting enabled * new selftests API for CPUID
2022-07-28KVM: SVM: Dump Virtual Machine Save Area (VMSA) to klogJarkko Sakkinen
As Virtual Machine Save Area (VMSA) is essential in troubleshooting attestation, dump it to the klog with the KERN_DEBUG level of priority. Cc: Jarkko Sakkinen <jarkko@kernel.org> Suggested-by: Harald Hoyer <harald@profian.com> Signed-off-by: Jarkko Sakkinen <jarkko@profian.com> Message-Id: <20220728050919.24113-1-jarkko@profian.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-06-24KVM: SEV: Init target VMCBs in sev_migrate_fromPeter Gonda
The target VMCBs during an intra-host migration need to correctly setup for running SEV and SEV-ES guests. Add sev_init_vmcb() function and make sev_es_init_vmcb() static. sev_init_vmcb() uses the now private function to init SEV-ES guests VMCBs when needed. Fixes: 0b020f5af092 ("KVM: SEV: Add support for SEV-ES intra host migration") Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration") Signed-off-by: Peter Gonda <pgonda@google.com> Cc: Marc Orr <marcorr@google.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sean Christopherson <seanjc@google.com> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Message-Id: <20220623173406.744645-1-pgonda@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-06-24KVM: x86/svm: add __GFP_ACCOUNT to __sev_dbg_{en,de}crypt_user()Mingwei Zhang
Adding the accounting flag when allocating pages within the SEV function, since these memory pages should belong to individual VM. No functional change intended. Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220623171858.2083637-1-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-06-15KVM: SVM: Hide SEV migration lockdep goo behind CONFIG_PROVE_LOCKINGSean Christopherson
Wrap the manipulation of @role and the manual mutex_{release,acquire}() invocations in CONFIG_PROVE_LOCKING=y to squash a clang-15 warning. When building with -Wunused-but-set-parameter and CONFIG_DEBUG_LOCK_ALLOC=n, clang-15 seees there's no usage of @role in mutex_lock_killable_nested() and yells. PROVE_LOCKING selects DEBUG_LOCK_ALLOC, and the only reason KVM manipulates @role is to make PROVE_LOCKING happy. To avoid true ugliness, use "i" and "j" to detect the first pass in the loops; the "idx" field that's used by kvm_for_each_vcpu() is guaranteed to be '0' on the first pass as it's simply the first entry in the vCPUs XArray, which is fully KVM controlled. kvm_for_each_vcpu() passes '0' for xa_for_each_range()'s "start", and xa_for_each_range() will not enter the loop if there's no entry at '0'. Fixes: 0c2c7c069285 ("KVM: SEV: Mark nested locking of vcpu->lock") Reported-by: kernel test robot <lkp@intel.com> Cc: Peter Gonda <pgonda@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220613214237.2538266-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-26Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds
Pull kvm updates from Paolo Bonzini: "S390: - ultravisor communication device driver - fix TEID on terminating storage key ops RISC-V: - Added Sv57x4 support for G-stage page table - Added range based local HFENCE functions - Added remote HFENCE functions based on VCPU requests - Added ISA extension registers in ONE_REG interface - Updated KVM RISC-V maintainers entry to cover selftests support ARM: - Add support for the ARMv8.6 WFxT extension - Guard pages for the EL2 stacks - Trap and emulate AArch32 ID registers to hide unsupported features - Ability to select and save/restore the set of hypercalls exposed to the guest - Support for PSCI-initiated suspend in collaboration with userspace - GICv3 register-based LPI invalidation support - Move host PMU event merging into the vcpu data structure - GICv3 ITS save/restore fixes - The usual set of small-scale cleanups and fixes x86: - New ioctls to get/set TSC frequency for a whole VM - Allow userspace to opt out of hypercall patching - Only do MSR filtering for MSRs accessed by rdmsr/wrmsr AMD SEV improvements: - Add KVM_EXIT_SHUTDOWN metadata for SEV-ES - V_TSC_AUX support Nested virtualization improvements for AMD: - Support for "nested nested" optimizations (nested vVMLOAD/VMSAVE, nested vGIF) - Allow AVIC to co-exist with a nested guest running - Fixes for LBR virtualizations when a nested guest is running, and nested LBR virtualization support - PAUSE filtering for nested hypervisors Guest support: - Decoupling of vcpu_is_preempted from PV spinlocks" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (199 commits) KVM: x86: Fix the intel_pt PMI handling wrongly considered from guest KVM: selftests: x86: Sync the new name of the test case to .gitignore Documentation: kvm: reorder ARM-specific section about KVM_SYSTEM_EVENT_SUSPEND x86, kvm: use correct GFP flags for preemption disabled KVM: LAPIC: Drop pending LAPIC timer injection when canceling the timer x86/kvm: Alloc dummy async #PF token outside of raw spinlock KVM: x86: avoid calling x86 emulator without a decoded instruction KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leak x86/fpu: KVM: Set the base guest FPU uABI size to sizeof(struct kvm_xsave) s390/uv_uapi: depend on CONFIG_S390 KVM: selftests: x86: Fix test failure on arch lbr capable platforms KVM: LAPIC: Trace LAPIC timer expiration on every vmentry KVM: s390: selftest: Test suppression indication on key prot exception KVM: s390: Don't indicate suppression on dirtying, failing memop selftests: drivers/s390x: Add uvdevice tests drivers/s390/char: Add Ultravisor io device MAINTAINERS: Update KVM RISC-V entry to cover selftests support RISC-V: KVM: Introduce ISA extension register RISC-V: KVM: Cleanup stale TLB entries when host CPU changes RISC-V: KVM: Add remote HFENCE functions based on VCPU requests ...
2022-05-25KVM: SVM: Use kzalloc for sev ioctl interfaces to prevent kernel data leakAshish Kalra
For some sev ioctl interfaces, the length parameter that is passed maybe less than or equal to SEV_FW_BLOB_MAX_SIZE, but larger than the data that PSP firmware returns. In this case, kmalloc will allocate memory that is the size of the input rather than the size of the data. Since PSP firmware doesn't fully overwrite the allocated buffer, these sev ioctl interface may return uninitialized kernel slab memory. Reported-by: Andy Nguyen <theflow@google.com> Suggested-by: David Rientjes <rientjes@google.com> Suggested-by: Peter Gonda <pgonda@google.com> Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Fixes: eaf78265a4ab3 ("KVM: SVM: Move SEV code to separate file") Fixes: 2c07ded06427d ("KVM: SVM: add support for SEV attestation command") Fixes: 4cfdd47d6d95a ("KVM: SVM: Add KVM_SEV SEND_START command") Fixes: d3d1af85e2c75 ("KVM: SVM: Add KVM_SEND_UPDATE_DATA command") Fixes: eba04b20e4861 ("KVM: x86: Account a variety of miscellaneous allocations") Signed-off-by: Ashish Kalra <ashish.kalra@amd.com> Reviewed-by: Peter Gonda <pgonda@google.com> Message-Id: <20220516154310.3685678-1-Ashish.Kalra@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-25Merge tag 'kvm-riscv-5.19-1' of https://github.com/kvm-riscv/linux into HEADPaolo Bonzini
KVM/riscv changes for 5.19 - Added Sv57x4 support for G-stage page table - Added range based local HFENCE functions - Added remote HFENCE functions based on VCPU requests - Added ISA extension registers in ONE_REG interface - Updated KVM RISC-V maintainers entry to cover selftests support
2022-05-25Merge tag 'kvmarm-5.19' of ↵Paolo Bonzini
git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD KVM/arm64 updates for 5.19 - Add support for the ARMv8.6 WFxT extension - Guard pages for the EL2 stacks - Trap and emulate AArch32 ID registers to hide unsupported features - Ability to select and save/restore the set of hypercalls exposed to the guest - Support for PSCI-initiated suspend in collaboration with userspace - GICv3 register-based LPI invalidation support - Move host PMU event merging into the vcpu data structure - GICv3 ITS save/restore fixes - The usual set of small-scale cleanups and fixes [Due to the conflict, KVM_SYSTEM_EVENT_SEV_TERM is relocated from 4 to 6. - Paolo]
2022-05-23Merge tag 'x86_sev_for_v5.19_rc1' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull AMD SEV-SNP support from Borislav Petkov: "The third AMD confidential computing feature called Secure Nested Paging. Add to confidential guests the necessary memory integrity protection against malicious hypervisor-based attacks like data replay, memory remapping and others, thus achieving a stronger isolation from the hypervisor. At the core of the functionality is a new structure called a reverse map table (RMP) with which the guest has a say in which pages get assigned to it and gets notified when a page which it owns, gets accessed/modified under the covers so that the guest can take an appropriate action. In addition, add support for the whole machinery needed to launch a SNP guest, details of which is properly explained in each patch. And last but not least, the series refactors and improves parts of the previous SEV support so that the new code is accomodated properly and not just bolted on" * tag 'x86_sev_for_v5.19_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (60 commits) x86/entry: Fixup objtool/ibt validation x86/sev: Mark the code returning to user space as syscall gap x86/sev: Annotate stack change in the #VC handler x86/sev: Remove duplicated assignment to variable info x86/sev: Fix address space sparse warning x86/sev: Get the AP jump table address from secrets page x86/sev: Add missing __init annotations to SEV init routines virt: sevguest: Rename the sevguest dir and files to sev-guest virt: sevguest: Change driver name to reflect generic SEV support x86/boot: Put globals that are accessed early into the .data section x86/boot: Add an efi.h header for the decompressor virt: sevguest: Fix bool function returning negative value virt: sevguest: Fix return value check in alloc_shared_pages() x86/sev-es: Replace open-coded hlt-loop with sev_es_terminate() virt: sevguest: Add documentation for SEV-SNP CPUID Enforcement virt: sevguest: Add support to get extended report virt: sevguest: Add support to derive key virt: Add SEV-SNP guest driver x86/sev: Register SEV-SNP guest request platform device x86/sev: Provide support for SNP guest request NAEs ...
2022-05-06KVM: SEV: Mark nested locking of vcpu->lockPeter Gonda
svm_vm_migrate_from() uses sev_lock_vcpus_for_migration() to lock all source and target vcpu->locks. Unfortunately there is an 8 subclass limit, so a new subclass cannot be used for each vCPU. Instead maintain ownership of the first vcpu's mutex.dep_map using a role specific subclass: source vs target. Release the other vcpu's mutex.dep_maps. Fixes: b56639318bb2b ("KVM: SEV: Add support for SEV intra host migration") Reported-by: John Sperbeck<jsperbeck@google.com> Suggested-by: David Rientjes <rientjes@google.com> Suggested-by: Sean Christopherson <seanjc@google.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Cc: Hillf Danton <hdanton@sina.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Peter Gonda <pgonda@google.com> Message-Id: <20220502165807.529624-1-pgonda@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-29KVM: SEV-ES: Use V_TSC_AUX if available instead of RDTSC/MSR_TSC_AUX interceptsBabu Moger
The TSC_AUX virtualization feature allows AMD SEV-ES guests to securely use TSC_AUX (auxiliary time stamp counter data) in the RDTSCP and RDPID instructions. The TSC_AUX value is set using the WRMSR instruction to the TSC_AUX MSR (0xC0000103). It is read by the RDMSR, RDTSCP and RDPID instructions. If the read/write of the TSC_AUX MSR is intercepted, then RDTSCP and RDPID must also be intercepted when TSC_AUX virtualization is present. However, the RDPID instruction can't be intercepted. This means that when TSC_AUX virtualization is present, RDTSCP and TSC_AUX MSR read/write must not be intercepted for SEV-ES (or SEV-SNP) guests. Signed-off-by: Babu Moger <babu.moger@amd.com> Message-Id: <165040164424.1399644.13833277687385156344.stgit@bmoger-ubuntu> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-29Merge branch 'kvm-fixes-for-5.18-rc5' into HEADPaolo Bonzini
Fixes for (relatively) old bugs, to be merged in both the -rc and next development trees. The merge reconciles the ABI fixes for KVM_EXIT_SYSTEM_EVENT between 5.18 and commit c24a950ec7d6 ("KVM, SEV: Add KVM_EXIT_SHUTDOWN metadata for SEV-ES", 2022-04-13).
2022-04-21KVM: SEV: add cache flush to solve SEV cache incoherency issuesMingwei Zhang
Flush the CPU caches when memory is reclaimed from an SEV guest (where reclaim also includes it being unmapped from KVM's memslots). Due to lack of coherency for SEV encrypted memory, failure to flush results in silent data corruption if userspace is malicious/broken and doesn't ensure SEV guest memory is properly pinned and unpinned. Cache coherency is not enforced across the VM boundary in SEV (AMD APM vol.2 Section 15.34.7). Confidential cachelines, generated by confidential VM guests have to be explicitly flushed on the host side. If a memory page containing dirty confidential cachelines was released by VM and reallocated to another user, the cachelines may corrupt the new user at a later time. KVM takes a shortcut by assuming all confidential memory remain pinned until the end of VM lifetime. Therefore, KVM does not flush cache at mmu_notifier invalidation events. Because of this incorrect assumption and the lack of cache flushing, malicous userspace can crash the host kernel: creating a malicious VM and continuously allocates/releases unpinned confidential memory pages when the VM is running. Add cache flush operations to mmu_notifier operations to ensure that any physical memory leaving the guest VM get flushed. In particular, hook mmu_notifier_invalidate_range_start and mmu_notifier_release events and flush cache accordingly. The hook after releasing the mmu lock to avoid contention with other vCPUs. Cc: stable@vger.kernel.org Suggested-by: Sean Christpherson <seanjc@google.com> Reported-by: Mingwei Zhang <mizhang@google.com> Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220421031407.2516575-4-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-21KVM: SVM: Flush when freeing encrypted pages even on SME_COHERENT CPUsMingwei Zhang
Use clflush_cache_range() to flush the confidential memory when SME_COHERENT is supported in AMD CPU. Cache flush is still needed since SME_COHERENT only support cache invalidation at CPU side. All confidential cache lines are still incoherent with DMA devices. Cc: stable@vger.kerel.org Fixes: add5e2f04541 ("KVM: SVM: Add support for the SEV-ES VMSA") Reviewed-by: Sean Christopherson <seanjc@google.com> Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220421031407.2516575-3-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-21KVM: SVM: Simplify and harden helper to flush SEV guest page(s)Sean Christopherson
Rework sev_flush_guest_memory() to explicitly handle only a single page, and harden it to fall back to WBINVD if VM_PAGE_FLUSH fails. Per-page flushing is currently used only to flush the VMSA, and in its current form, the helper is completely broken with respect to flushing actual guest memory, i.e. won't work correctly for an arbitrary memory range. VM_PAGE_FLUSH takes a host virtual address, and is subject to normal page walks, i.e. will fault if the address is not present in the host page tables or does not have the correct permissions. Current AMD CPUs also do not honor SMAP overrides (undocumented in kernel versions of the APM), so passing in a userspace address is completely out of the question. In other words, KVM would need to manually walk the host page tables to get the pfn, ensure the pfn is stable, and then use the direct map to invoke VM_PAGE_FLUSH. And the latter might not even work, e.g. if userspace is particularly evil/clever and backs the guest with Secret Memory (which unmaps memory from the direct map). Signed-off-by: Sean Christopherson <seanjc@google.com> Fixes: add5e2f04541 ("KVM: SVM: Add support for the SEV-ES VMSA") Reported-by: Mingwei Zhang <mizhang@google.com> Cc: stable@vger.kernel.org Signed-off-by: Mingwei Zhang <mizhang@google.com> Message-Id: <20220421031407.2516575-2-mizhang@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-13KVM, SEV: Add KVM_EXIT_SHUTDOWN metadata for SEV-ESPeter Gonda
If an SEV-ES guest requests termination, exit to userspace with KVM_EXIT_SYSTEM_EVENT and a dedicated SEV_TERM type instead of -EINVAL so that userspace can take appropriate action. See AMD's GHCB spec section '4.1.13 Termination Request' for more details. Suggested-by: Sean Christopherson <seanjc@google.com> Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Peter Gonda <pgonda@google.com> Reported-by: kernel test robot <lkp@intel.com> Message-Id: <20220407210233.782250-1-pgonda@google.com> [Add documentatino. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-11KVM: SVM: Do not activate AVIC for SEV-enabled guestSuravee Suthikulpanit
Since current AVIC implementation cannot support encrypted memory, inhibit AVIC for SEV-enabled guest. Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Message-Id: <20220408133710.54275-1-suravee.suthikulpanit@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-04-06KVM: SVM: Create a separate mapping for the SEV-ES save areaTom Lendacky
The save area for SEV-ES/SEV-SNP guests, as used by the hardware, is different from the save area of a non SEV-ES/SEV-SNP guest. This is the first step in defining the multiple save areas to keep them separate and ensuring proper operation amongst the different types of guests. Create an SEV-ES/SEV-SNP save area and adjust usage to the new save area definition where needed. Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com> Link: https://lore.kernel.org/r/20220405182743.308853-1-brijesh.singh@amd.com
2022-04-05KVM: SEV: Add cond_resched() to loop in sev_clflush_pages()Peter Gonda
Add resched to avoid warning from sev_clflush_pages() with large number of pages. Signed-off-by: Peter Gonda <pgonda@google.com> Cc: Sean Christopherson <seanjc@google.com> Cc: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org Message-Id: <20220330164306.2376085-1-pgonda@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-03-01KVM: SVM: Exit to userspace on ENOMEM/EFAULT GHCB errorsSean Christopherson
Exit to userspace if setup_vmgexit_scratch() fails due to OOM or because copying data from guest (userspace) memory failed/faulted. The OOM scenario is clearcut, it's userspace's decision as to whether it should terminate the guest, free memory, etc... As for -EFAULT, arguably, any guest issue is a violation of the guest's contract with userspace, and thus userspace needs to decide how to proceed. E.g. userspace defines what is RAM vs. MMIO and communicates that directly to the guest, KVM is not involved in deciding what is/isn't RAM nor in communicating that information to the guest. If the scratch GPA doesn't resolve to a memslot, then the guest is not honoring the memory configuration as defined by userspace. And if userspace unmaps an hva for whatever reason, then exiting to userspace with -EFAULT is absolutely the right thing to do. KVM's ABI currently sucks and doesn't provide enough information to act on the -EFAULT, but that will hopefully be remedied in the future as there are multiple use cases, e.g. uffd and virtiofs truncation, that shouldn't require any work in KVM beyond returning -EFAULT with a small amount of metadata. KVM could define its ABI such that failure to access the scratch area is reflected into the guest, i.e. establish a contract with userspace, but that's undesirable as it limits KVM's options in the future, e.g. in the potential uffd case any failure on a uaccess needs to kick out to userspace. KVM does have several cases where it reflects these errors into the guest, e.g. kvm_pv_clock_pairing() and Hyper-V emulation, but KVM would preferably "fix" those instead of propagating the falsehood that any memory failure is the guest's fault. Lastly, returning a boolean as an "error" for that a helper that isn't named accordingly never works out well. Fixes: ad5b353240c8 ("KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure") Cc: Alper Gun <alpergun@google.com> Cc: Peter Gonda <pgonda@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Message-Id: <20220225205209.3881130-1-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>