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. Since SVM already has specific handlers of MSR_IA32_DEBUGMSR in the svm_get/set_msr, move x86 commmon part to VMX and add the bus lock debug exception support. Co-developed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx> Signed-off-by: Chenyi Qiang <chenyi.qiang@xxxxxxxxx> --- arch/x86/kvm/cpuid.c | 3 ++- arch/x86/kvm/vmx/vmx.c | 23 +++++++++++++++++++++-- arch/x86/kvm/x86.c | 16 ++-------------- arch/x86/kvm/x86.h | 2 ++ 4 files changed, 27 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 83637a2ff605..af4feb0ec178 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -401,7 +401,8 @@ void kvm_set_cpu_caps(void) F(AVX512VBMI) | F(LA57) | F(PKU) | 0 /*OSPKE*/ | F(RDPID) | 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(CLDEMOTE) | F(MOVDIRI) | F(MOVDIR64B) | 0 /*WAITPKG*/ | + F(BUS_LOCK_DETECT) ); /* Set LA57 based on hardware capability. */ if (cpuid_ecx(7) & F(LA57)) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 892340b031cb..9d6deca79345 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -148,6 +148,9 @@ module_param(allow_smaller_maxphyaddr, bool, S_IRUGO); RTIT_STATUS_ERROR | RTIT_STATUS_STOPPED | \ RTIT_STATUS_BYTECNT)) +#define MSR_VMX_SUPPORTED_DEBUGCTL (DEBUGCTLMSR_LBR | \ + DEBUGCTLMSR_BTF | DEBUGCTLMSR_BUS_LOCK_DETECT) + /* * List of MSRs that can be directly passed to the guest. * In addition to these x2apic and PT MSRs are handled specially. @@ -1925,6 +1928,9 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) !guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP)) return 1; goto find_uret_msr; + case MSR_IA32_DEBUGCTLMSR: + msr_info->data = vmcs_read64(GUEST_IA32_DEBUGCTL); + break; default: find_uret_msr: msr = vmx_find_uret_msr(vmx, msr_info->index); @@ -2003,9 +2009,22 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) VM_EXIT_SAVE_DEBUG_CONTROLS) get_vmcs12(vcpu)->guest_ia32_debugctl = data; - ret = kvm_set_msr_common(vcpu, msr_info); - break; + if (data & ~MSR_VMX_SUPPORTED_DEBUGCTL) + return 1; + if (!msr_info->host_initiated && + (data & DEBUGCTLMSR_BUS_LOCK_DETECT) && + !guest_cpuid_has(vcpu, X86_FEATURE_BUS_LOCK_DETECT)) + return 1; + + if (data & (DEBUGCTLMSR_BTF|DEBUGCTLMSR_LBR)) { + if (report_ignored_msrs) + vcpu_unimpl(vcpu, "%s: BTF|LBR in MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n", + __func__, data); + data &= ~(DEBUGCTLMSR_BTF|DEBUGCTLMSR_LBR); + } + vmcs_write64(GUEST_IA32_DEBUGCTL, data); + return 0; case MSR_IA32_BNDCFGS: if (!kvm_mpx_supported() || (!msr_info->host_initiated && diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 2d506210f1f9..d547b70865b1 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -116,8 +116,9 @@ EXPORT_SYMBOL_GPL(kvm_x86_ops); static bool __read_mostly ignore_msrs = 0; module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR); -static bool __read_mostly report_ignored_msrs = true; +bool __read_mostly report_ignored_msrs = true; module_param(report_ignored_msrs, bool, S_IRUGO | S_IWUSR); +EXPORT_SYMBOL_GPL(report_ignored_msrs); unsigned int min_timer_period_us = 200; module_param(min_timer_period_us, uint, S_IRUGO | S_IWUSR); @@ -3061,18 +3062,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) return 1; } break; - case MSR_IA32_DEBUGCTLMSR: - if (!data) { - /* We support the non-activated case already */ - break; - } else if (data & ~(DEBUGCTLMSR_LBR | DEBUGCTLMSR_BTF)) { - /* Values other than LBR and BTF are vendor-specific, - thus reserved and should throw a #GP */ - return 1; - } else if (report_ignored_msrs) - vcpu_unimpl(vcpu, "%s: MSR_IA32_DEBUGCTLMSR 0x%llx, nop\n", - __func__, data); - break; case 0x200 ... 0x2ff: return kvm_mtrr_set_msr(vcpu, msr, data); case MSR_IA32_APICBASE: @@ -3345,7 +3334,6 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info) switch (msr_info->index) { case MSR_IA32_PLATFORM_ID: case MSR_IA32_EBL_CR_POWERON: - case MSR_IA32_DEBUGCTLMSR: case MSR_IA32_LASTBRANCHFROMIP: case MSR_IA32_LASTBRANCHTOIP: case MSR_IA32_LASTINTFROMIP: diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index e7ca622a468f..6e7fa5b0a216 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -294,6 +294,8 @@ extern int pi_inject_timer; extern struct static_key kvm_no_apic_vcpu; +extern bool report_ignored_msrs; + static inline u64 nsec_to_cycles(struct kvm_vcpu *vcpu, u64 nsec) { return pvclock_scale_delta(nsec, vcpu->arch.virtual_tsc_mult, -- 2.17.1