lwn.git/arch/arm/include/asm/kvm_host.h, branch docs-5.6

Merge remote-tracking branch 'kvmarm/kvm-arm64/stolen-time' into kvmarm-master/next

2019-10-24T14:04:09+00:00

KVM: arm64: Support stolen time reporting via shared structure

2019-10-21T18:20:28+00:00

Implement the service call for configuring a shared structure between a VCPU and the hypervisor in which the hypervisor can write the time stolen from the VCPU's execution time by other tasks on the host. User space allocates memory which is placed at an IPA also chosen by user space. The hypervisor then updates the shared structure using kvm_put_guest() to ensure single copy atomicity of the 64-bit value reporting the stolen time in nanoseconds. Whenever stolen time is enabled by the guest, the stolen time counter is reset. The stolen time itself is retrieved from the sched_info structure maintained by the Linux scheduler code. We enable SCHEDSTATS when selecting KVM Kconfig to ensure this value is meaningful. Signed-off-by: Steven Price Signed-off-by: Marc Zyngier

KVM: arm64: Implement PV_TIME_FEATURES call

2019-10-21T18:20:27+00:00

This provides a mechanism for querying which paravirtualized time features are available in this hypervisor. Also add the header file which defines the ABI for the paravirtualized time features we're about to add. Signed-off-by: Steven Price Signed-off-by: Marc Zyngier

KVM: arm/arm64: Allow reporting non-ISV data aborts to userspace

2019-10-21T17:59:44+00:00

For a long time, if a guest accessed memory outside of a memslot using any of the load/store instructions in the architecture which doesn't supply decoding information in the ESR_EL2 (the ISV bit is not set), the kernel would print the following message and terminate the VM as a result of returning -ENOSYS to userspace: load/store instruction decoding not implemented The reason behind this message is that KVM assumes that all accesses outside a memslot is an MMIO access which should be handled by userspace, and we originally expected to eventually implement some sort of decoding of load/store instructions where the ISV bit was not set. However, it turns out that many of the instructions which don't provide decoding information on abort are not safe to use for MMIO accesses, and the remaining few that would potentially make sense to use on MMIO accesses, such as those with register writeback, are not used in practice. It also turns out that fetching an instruction from guest memory can be a pretty horrible affair, involving stopping all CPUs on SMP systems, handling multiple corner cases of address translation in software, and more. It doesn't appear likely that we'll ever implement this in the kernel. What is much more common is that a user has misconfigured his/her guest and is actually not accessing an MMIO region, but just hitting some random hole in the IPA space. In this scenario, the error message above is almost misleading and has led to a great deal of confusion over the years. It is, nevertheless, ABI to userspace, and we therefore need to introduce a new capability that userspace explicitly enables to change behavior. This patch introduces KVM_CAP_ARM_NISV_TO_USER (NISV meaning Non-ISV) which does exactly that, and introduces a new exit reason to report the event to userspace. User space can then emulate an exception to the guest, restart the guest, suspend the guest, or take any other appropriate action as per the policy of the running system. Reported-by: Heinrich Schuchardt Signed-off-by: Christoffer Dall Reviewed-by: Alexander Graf Signed-off-by: Marc Zyngier

KVM: arm/arm64: Initialise host's MPIDRs by reading the actual register

2019-07-08T15:29:48+00:00

As part of setting up the host context, we populate its MPIDR by using cpu_logical_map(). It turns out that contrary to arm64, cpu_logical_map() on 32bit ARM doesn't return the *full* MPIDR, but a truncated version. This leaves the host MPIDR slightly corrupted after the first run of a VM, since we won't correctly restore the MPIDR on exit. Oops. Since we cannot trust cpu_logical_map(), let's adopt a different strategy. We move the initialization of the host CPU context as part of the per-CPU initialization (which, in retrospect, makes a lot of sense), and directly read the MPIDR from the HW. This is guaranteed to work on both arm and arm64. Reported-by: Andre Przywara Tested-by: Andre Przywara Fixes: 32f139551954 ("arm/arm64: KVM: Statically configure the host's view of MPIDR") Signed-off-by: Marc Zyngier

arm64: KVM: Propagate full Spectre v2 workaround state to KVM guests

2019-07-05T12:56:27+00:00

Recent commits added the explicit notion of "workaround not required" to the state of the Spectre v2 (aka. BP_HARDENING) workaround, where we just had "needed" and "unknown" before. Export this knowledge to the rest of the kernel and enhance the existing kvm_arm_harden_branch_predictor() to report this new state as well. Export this new state to guests when they use KVM's firmware interface emulation. Signed-off-by: Andre Przywara Reviewed-by: Steven Price Signed-off-by: Marc Zyngier

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 266

2019-06-05T15:30:28+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not write to the free software foundation 51 franklin street fifth floor boston ma 02110 1301 usa extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 67 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Richard Fontana Reviewed-by: Alexios Zavras Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141333.953658117@linutronix.de Signed-off-by: Greg Kroah-Hartman

arm64: KVM: Enable VHE support for :G/:H perf event modifiers

2019-04-24T14:46:26+00:00

With VHE different exception levels are used between the host (EL2) and guest (EL1) with a shared exception level for userpace (EL0). We can take advantage of this and use the PMU's exception level filtering to avoid enabling/disabling counters in the world-switch code. Instead we just modify the counter type to include or exclude EL0 at vcpu_{load,put} time. We also ensure that trapped PMU system register writes do not re-enable EL0 when reconfiguring the backing perf events. This approach completely avoids blackout windows seen with !VHE. Suggested-by: Christoffer Dall Signed-off-by: Andrew Murray Acked-by: Will Deacon Reviewed-by: Suzuki K Poulose Signed-off-by: Marc Zyngier

arm64: KVM: Encapsulate kvm_cpu_context in kvm_host_data

2019-04-24T14:35:24+00:00

The virt/arm core allocates a kvm_cpu_context_t percpu, at present this is a typedef to kvm_cpu_context and is used to store host cpu context. The kvm_cpu_context structure is also used elsewhere to hold vcpu context. In order to use the percpu to hold additional future host information we encapsulate kvm_cpu_context in a new structure and rename the typedef and percpu to match. Signed-off-by: Andrew Murray Reviewed-by: Suzuki K Poulose Signed-off-by: Marc Zyngier

KVM: arm/arm64: Clean up vcpu finalization function parameter naming

2019-04-18T16:14:02+00:00

Currently, the internal vcpu finalization functions use a different name ("what") for the feature parameter than the name ("feature") used in the documentation. To avoid future confusion, this patch converts everything to use the name "feature" consistently. No functional change. Suggested-by: Andrew Jones Signed-off-by: Dave Martin Reviewed-by: Andrew Jones Signed-off-by: Marc Zyngier