From f2a55d08d7e1a5746dad80fc5eda023eff2eeea5 Mon Sep 17 00:00:00 2001 From: Saurabh Sengar Date: Tue, 19 Sep 2023 21:04:35 -0700 Subject: x86/hyperv: Restrict get_vtl to only VTL platforms When Linux runs in a non-default VTL (CONFIG_HYPERV_VTL_MODE=y), get_vtl() must never fail as its return value is used in negotiations with the host. In the more generic case, (CONFIG_HYPERV_VTL_MODE=n) the VTL is always zero so there's no need to do the hypercall. Make get_vtl() BUG() in case of failure and put the implementation under "if IS_ENABLED(CONFIG_HYPERV_VTL_MODE)" to avoid the call altogether in the most generic use case. Signed-off-by: Saurabh Sengar Reviewed-by: Vitaly Kuznetsov Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/1695182675-13405-1-git-send-email-ssengar@linux.microsoft.com --- arch/x86/hyperv/hv_init.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'arch') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 783ed339f341..f0128fd4031d 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -394,6 +394,7 @@ static void __init hv_get_partition_id(void) local_irq_restore(flags); } +#if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) static u8 __init get_vtl(void) { u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS; @@ -416,13 +417,16 @@ static u8 __init get_vtl(void) if (hv_result_success(ret)) { ret = output->as64.low & HV_X64_VTL_MASK; } else { - pr_err("Failed to get VTL(%lld) and set VTL to zero by default.\n", ret); - ret = 0; + pr_err("Failed to get VTL(error: %lld) exiting...\n", ret); + BUG(); } local_irq_restore(flags); return ret; } +#else +static inline u8 get_vtl(void) { return 0; } +#endif /* * This function is to be invoked early in the boot sequence after the @@ -604,8 +608,7 @@ skip_hypercall_pg_init: hv_query_ext_cap(0); /* Find the VTL */ - if (!ms_hyperv.paravisor_present && hv_isolation_type_snp()) - ms_hyperv.vtl = get_vtl(); + ms_hyperv.vtl = get_vtl(); return; -- cgit v1.2.3 From 14058f72cf13e476bcc3b4e9922a8cb2e59783d2 Mon Sep 17 00:00:00 2001 From: Saurabh Sengar Date: Thu, 21 Sep 2023 21:58:40 -0700 Subject: x86/hyperv: Remove hv_vtl_early_init initcall There has been cases reported where HYPERV_VTL_MODE is enabled by mistake, on a non Hyper-V platforms. This causes the hv_vtl_early_init function to be called in an non Hyper-V/VTL platforms which results the memory corruption. Remove the early_initcall for hv_vtl_early_init and call it at the end of hyperv_init to make sure it is never called in a non Hyper-V platform by mistake. Reported-by: Mathias Krause Closes: https://lore.kernel.org/lkml/40467722-f4ab-19a5-4989-308225b1f9f0@grsecurity.net/ Signed-off-by: Saurabh Sengar Acked-by: Mathias Krause Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/1695358720-27681-1-git-send-email-ssengar@linux.microsoft.com --- arch/x86/hyperv/hv_init.c | 3 +++ arch/x86/hyperv/hv_vtl.c | 3 +-- arch/x86/include/asm/mshyperv.h | 2 ++ 3 files changed, 6 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index f0128fd4031d..608f4fe41fb7 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -610,6 +610,9 @@ skip_hypercall_pg_init: /* Find the VTL */ ms_hyperv.vtl = get_vtl(); + if (ms_hyperv.vtl > 0) /* non default VTL */ + hv_vtl_early_init(); + return; clean_guest_os_id: diff --git a/arch/x86/hyperv/hv_vtl.c b/arch/x86/hyperv/hv_vtl.c index 36a562218010..999f5ac82fe9 100644 --- a/arch/x86/hyperv/hv_vtl.c +++ b/arch/x86/hyperv/hv_vtl.c @@ -215,7 +215,7 @@ static int hv_vtl_wakeup_secondary_cpu(int apicid, unsigned long start_eip) return hv_vtl_bringup_vcpu(vp_id, start_eip); } -static int __init hv_vtl_early_init(void) +int __init hv_vtl_early_init(void) { /* * `boot_cpu_has` returns the runtime feature support, @@ -230,4 +230,3 @@ static int __init hv_vtl_early_init(void) return 0; } -early_initcall(hv_vtl_early_init); diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h index 033b53f993c6..896445edc6a8 100644 --- a/arch/x86/include/asm/mshyperv.h +++ b/arch/x86/include/asm/mshyperv.h @@ -340,8 +340,10 @@ static inline u64 hv_get_non_nested_register(unsigned int reg) { return 0; } #ifdef CONFIG_HYPERV_VTL_MODE void __init hv_vtl_init_platform(void); +int __init hv_vtl_early_init(void); #else static inline void __init hv_vtl_init_platform(void) {} +static inline int __init hv_vtl_early_init(void) { return 0; } #endif #include -- cgit v1.2.3 From 203a521bd93c323ded93c5aa35069029d5c23611 Mon Sep 17 00:00:00 2001 From: Saurabh Sengar Date: Tue, 19 Sep 2023 04:36:01 -0700 Subject: x86/hyperv: Add common print prefix "Hyper-V" in hv_init Add "#define pr_fmt()" in hv_init.c to use "Hyper-V:" as common print prefix for all pr_*() statements in this file. Remove the "Hyper-V:" already prefixed in couple of prints. Signed-off-by: Saurabh Sengar Signed-off-by: Wei Liu Link: https://lore.kernel.org/r/1695123361-8877-1-git-send-email-ssengar@linux.microsoft.com --- arch/x86/hyperv/hv_init.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c index 608f4fe41fb7..21556ad87f4b 100644 --- a/arch/x86/hyperv/hv_init.c +++ b/arch/x86/hyperv/hv_init.c @@ -7,6 +7,8 @@ * Author : K. Y. Srinivasan */ +#define pr_fmt(fmt) "Hyper-V: " fmt + #include #include #include @@ -191,7 +193,7 @@ void set_hv_tscchange_cb(void (*cb)(void)) struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1}; if (!hv_reenlightenment_available()) { - pr_warn("Hyper-V: reenlightenment support is unavailable\n"); + pr_warn("reenlightenment support is unavailable\n"); return; } @@ -568,7 +570,7 @@ skip_hypercall_pg_init: if (cpu_feature_enabled(X86_FEATURE_IBT) && *(u32 *)hv_hypercall_pg != gen_endbr()) { setup_clear_cpu_cap(X86_FEATURE_IBT); - pr_warn("Hyper-V: Disabling IBT because of Hyper-V bug\n"); + pr_warn("Disabling IBT because of Hyper-V bug\n"); } #endif -- cgit v1.2.3