From 742458accadca19ea65a4ab2b33fbc3f82f38466 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 6 May 2021 06:30:04 -0400 Subject: [PATCH] KVM: X86: Expose bus lock debug exception to guest mainline inclusion from mainline-v5.13-rc2 commit 76ea438b4afcd9ee8da3387e9af4625eaccff58f category: feature feature: KVM Bus Lock Debug Exception bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I5RHW7 CVE: N/A Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/ commit/?id=76ea438b4afcd9ee8da3387e9af4625eaccff58f Intel-SIG: commit 76ea438b4afc ("KVM: X86: Expose bus lock debug exception to guest") ------------------------------------- KVM: X86: Expose bus lock debug exception to guest Bus lock debug exception is an ability to notify the kernel by an #DB trap after the instruction acquires a bus lock and is executed when CPL>0. This allows the kernel to enforce user application throttling or mitigations. Existence of bus lock debug exception is enumerated via CPUID.(EAX=7,ECX=0).ECX[24]. Software can enable these exceptions by setting bit 2 of the MSR_IA32_DEBUGCTL. Expose the CPUID to guest and emulate the MSR handling when guest enables it. Support for this feature was originally developed by Xiaoyao Li and Chenyi Qiang, but code has since changed enough that this patch has nothing in common with theirs, except for this commit message. Co-developed-by: Xiaoyao Li Signed-off-by: Xiaoyao Li Signed-off-by: Chenyi Qiang Message-Id: <20210202090433.13441-4-chenyi.qiang@intel.com> Signed-off-by: Paolo Bonzini Signed-off-by: Aichun Shi --- arch/x86/kvm/cpuid.c | 2 +- arch/x86/kvm/vmx/capabilities.h | 3 +++ arch/x86/kvm/vmx/vmx.c | 3 +++ 3 files changed, 7 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index c957e591401c..a9b505f63017 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -441,7 +441,7 @@ void kvm_set_cpu_caps(void) F(AVX512_VPOPCNTDQ) | F(UMIP) | F(AVX512_VBMI2) | F(GFNI) | F(VAES) | F(VPCLMULQDQ) | F(AVX512_VNNI) | F(AVX512_BITALG) | F(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ | - F(SGX_LC) + F(SGX_LC) | F(BUS_LOCK_DETECT) ); /* Set LA57 based on hardware capability. */ if (cpuid_ecx(7) & F(LA57)) diff --git a/arch/x86/kvm/vmx/capabilities.h b/arch/x86/kvm/vmx/capabilities.h index 1fc2d1415889..d6d13e5ac155 100644 --- a/arch/x86/kvm/vmx/capabilities.h +++ b/arch/x86/kvm/vmx/capabilities.h @@ -405,6 +405,9 @@ static inline u64 vmx_supported_debugctl(void) { u64 debugctl = 0; + if (boot_cpu_has(X86_FEATURE_BUS_LOCK_DETECT)) + debugctl |= DEBUGCTLMSR_BUS_LOCK_DETECT; + if (vmx_get_perf_capabilities() & PMU_CAP_LBR_FMT) debugctl |= DEBUGCTLMSR_LBR_MASK; diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b506f42da847..173e6185780c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -2076,6 +2076,9 @@ static u64 vcpu_supported_debugctl(struct kvm_vcpu *vcpu) if (!intel_pmu_lbr_is_enabled(vcpu)) debugctl &= ~DEBUGCTLMSR_LBR_MASK; + if (!guest_cpuid_has(vcpu, X86_FEATURE_BUS_LOCK_DETECT)) + debugctl &= ~DEBUGCTLMSR_BUS_LOCK_DETECT; + return debugctl; } -- GitLab