Messages in this thread | | | From | Like Xu <> | Subject | Re: [PATCH v7 05/15] KVM: vmx/pmu: Emulate MSR_ARCH_LBR_CTL for guest Arch LBR | Date | Mon, 9 Aug 2021 21:36:49 +0800 |
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On 6/8/2021 3:42 pm, Yang Weijiang wrote: > From: Like Xu <like.xu@linux.intel.com> > > Arch LBRs are enabled by setting MSR_ARCH_LBR_CTL.LBREn to 1. A new guest > state field named "Guest IA32_LBR_CTL" is added to enhance guest LBR usage. > When guest Arch LBR is enabled, a guest LBR event will be created like the > model-specific LBR does. Clear guest LBR enable bit on host PMI handling so > guest can see expected config. > > On processors that support Arch LBR, MSR_IA32_DEBUGCTLMSR[bit 0] has no > meaning. It can be written to 0 or 1, but reads will always return 0. > Like IA32_DEBUGCTL, IA32_ARCH_LBR_CTL msr is also preserved on INIT. > > Regardless of the Arch LBR or legacy LBR, when the LBR_EN bit 0 of the > corresponding control MSR is set to 1, LBR recording will be enabled. > > Signed-off-by: Like Xu <like.xu@linux.intel.com> > Signed-off-by: Yang Weijiang <weijiang.yang@intel.com> > --- > arch/x86/events/intel/lbr.c | 2 -- > arch/x86/include/asm/msr-index.h | 1 + > arch/x86/include/asm/vmx.h | 2 ++ > arch/x86/kvm/vmx/pmu_intel.c | 48 ++++++++++++++++++++++++++++---- > arch/x86/kvm/vmx/vmx.c | 9 ++++++ > 5 files changed, 55 insertions(+), 7 deletions(-) > > diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c > index ceff16eb4bcb..d6773a200c70 100644 > --- a/arch/x86/events/intel/lbr.c > +++ b/arch/x86/events/intel/lbr.c > @@ -168,8 +168,6 @@ enum { > ARCH_LBR_RETURN |\ > ARCH_LBR_OTHER_BRANCH) > > -#define ARCH_LBR_CTL_MASK 0x7f000e > - > static void intel_pmu_lbr_filter(struct cpu_hw_events *cpuc); > > static __always_inline bool is_lbr_call_stack_bit_set(u64 config) > diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h > index a7c413432b33..04059e8ed115 100644 > --- a/arch/x86/include/asm/msr-index.h > +++ b/arch/x86/include/asm/msr-index.h > @@ -169,6 +169,7 @@ > #define LBR_INFO_BR_TYPE (0xfull << LBR_INFO_BR_TYPE_OFFSET) > > #define MSR_ARCH_LBR_CTL 0x000014ce > +#define ARCH_LBR_CTL_MASK 0x7f000e > #define ARCH_LBR_CTL_LBREN BIT(0) > #define ARCH_LBR_CTL_CPL_OFFSET 1 > #define ARCH_LBR_CTL_CPL (0x3ull << ARCH_LBR_CTL_CPL_OFFSET) > diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h > index 0ffaa3156a4e..ea3be961cc8e 100644 > --- a/arch/x86/include/asm/vmx.h > +++ b/arch/x86/include/asm/vmx.h > @@ -245,6 +245,8 @@ enum vmcs_field { > GUEST_BNDCFGS_HIGH = 0x00002813, > GUEST_IA32_RTIT_CTL = 0x00002814, > GUEST_IA32_RTIT_CTL_HIGH = 0x00002815, > + GUEST_IA32_LBR_CTL = 0x00002816, > + GUEST_IA32_LBR_CTL_HIGH = 0x00002817, > HOST_IA32_PAT = 0x00002c00, > HOST_IA32_PAT_HIGH = 0x00002c01, > HOST_IA32_EFER = 0x00002c02, > diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c > index a4ef5bbce186..b2631fea5e6c 100644 > --- a/arch/x86/kvm/vmx/pmu_intel.c > +++ b/arch/x86/kvm/vmx/pmu_intel.c > @@ -19,6 +19,7 @@ > #include "pmu.h" > > #define MSR_PMC_FULL_WIDTH_BIT (MSR_IA32_PMC0 - MSR_IA32_PERFCTR0) > +#define KVM_ARCH_LBR_CTL_MASK (ARCH_LBR_CTL_MASK | ARCH_LBR_CTL_LBREN) > > static struct kvm_event_hw_type_mapping intel_arch_events[] = { > /* Index must match CPUID 0x0A.EBX bit vector */ > @@ -221,6 +222,7 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr) > ret = pmu->version > 1; > break; > case MSR_ARCH_LBR_DEPTH: > + case MSR_ARCH_LBR_CTL: > if (kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR)) > ret = guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR); > break; > @@ -369,6 +371,26 @@ static bool arch_lbr_depth_is_valid(struct kvm_vcpu *vcpu, u64 depth) > return (depth == fls(eax & 0xff) * 8); > } > > +#define ARCH_LBR_CTL_BRN_MASK GENMASK_ULL(22, 16) > + > +static bool arch_lbr_ctl_is_valid(struct kvm_vcpu *vcpu, u64 ctl) > +{ > + unsigned int eax, ebx, ecx, edx; > + > + if (!kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR)) > + return false; > + > + cpuid_count(0x1c, 0, &eax, &ebx, &ecx, &edx); > + if (!(ebx & BIT(0)) && (ctl & ARCH_LBR_CTL_CPL)) > + return false; > + if (!(ebx & BIT(2)) && (ctl & ARCH_LBR_CTL_STACK)) > + return false; > + if (!(ebx & BIT(1)) && (ctl & ARCH_LBR_CTL_BRN_MASK)) > + return false; > + > + return !(ctl & ~KVM_ARCH_LBR_CTL_MASK); > +}
Please check it with the *guest* cpuid entry.
And it should remove the bits that are not supported by x86_pmu.lbr_ctl_mask before vmcs_write64(...) if the guest value is a superset of the host value with warning message.
> + > static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > { > struct kvm_pmu *pmu = vcpu_to_pmu(vcpu); > @@ -392,6 +414,9 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > case MSR_ARCH_LBR_DEPTH: > msr_info->data = lbr_desc->records.nr; > return 0; > + case MSR_ARCH_LBR_CTL: > + msr_info->data = vmcs_read64(GUEST_IA32_LBR_CTL); > + return 0; > default: > if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) || > (pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) { > @@ -460,6 +485,15 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) > if (!msr_info->host_initiated) > wrmsrl(MSR_ARCH_LBR_DEPTH, lbr_desc->records.nr); > return 0; > + case MSR_ARCH_LBR_CTL: > + if (!arch_lbr_ctl_is_valid(vcpu, data)) > + break; > + > + vmcs_write64(GUEST_IA32_LBR_CTL, data); > + if (intel_pmu_lbr_is_enabled(vcpu) && !lbr_desc->event && > + (data & ARCH_LBR_CTL_LBREN)) > + intel_pmu_create_guest_lbr_event(vcpu); > + return 0; > default: > if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) || > (pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) { > @@ -637,12 +671,16 @@ static void intel_pmu_reset(struct kvm_vcpu *vcpu) > */ > static void intel_pmu_legacy_freezing_lbrs_on_pmi(struct kvm_vcpu *vcpu) > { > - u64 data = vmcs_read64(GUEST_IA32_DEBUGCTL); > + u32 lbr_ctl_field = GUEST_IA32_DEBUGCTL; > > - if (data & DEBUGCTLMSR_FREEZE_LBRS_ON_PMI) { > - data &= ~DEBUGCTLMSR_LBR; > - vmcs_write64(GUEST_IA32_DEBUGCTL, data); > - } > + if (!(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_FREEZE_LBRS_ON_PMI)) > + return; > + > + if (kvm_cpu_cap_has(X86_FEATURE_ARCH_LBR) && > + guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR)) > + lbr_ctl_field = GUEST_IA32_LBR_CTL; > + > + vmcs_write64(lbr_ctl_field, vmcs_read64(lbr_ctl_field) & ~0x1ULL); > } > > static void intel_pmu_deliver_pmi(struct kvm_vcpu *vcpu) > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 927a552393b9..e8df44faf900 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -2002,6 +2002,13 @@ 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; > > + /* > + * For Arch LBR, IA32_DEBUGCTL[bit 0] has no meaning. > + * It can be written to 0 or 1, but reads will always return 0. > + */ > + if (guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR)) > + data &= ~DEBUGCTLMSR_LBR; > + > vmcs_write64(GUEST_IA32_DEBUGCTL, data); > if (intel_pmu_lbr_is_enabled(vcpu) && !to_vmx(vcpu)->lbr_desc.event && > (data & DEBUGCTLMSR_LBR)) > @@ -4441,6 +4448,8 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event) > vmcs_writel(GUEST_SYSENTER_ESP, 0); > vmcs_writel(GUEST_SYSENTER_EIP, 0); > vmcs_write64(GUEST_IA32_DEBUGCTL, 0); > + if (static_cpu_has(X86_FEATURE_ARCH_LBR)) > + vmcs_write64(GUEST_IA32_LBR_CTL, 0);
Please update dump_vmcs() to dump GUEST_IA32_LBR_CTL as well.
How about update the load_vmcs12_host_state() for GUEST_IA32_LBR_CTL since you enabled the nested case in this patch set ?
> } > > kvm_set_rflags(vcpu, X86_EFLAGS_FIXED); >
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