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KVM: x86/pmu: Use separate array for defining "PMU MSRs to save"
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Move all potential to-be-saved PMU MSRs into a separate array so that a
future patch can easily omit all PMU MSRs from the list when the PMU is
disabled.

No functional change intended.

Link: https://lore.kernel.org/r/20230124234905.3774678-4-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
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@sean-jc
sean-jc committed Jan 27, 2023
1 parent e76ae52 commit 2374b73
Showing 1 changed file with 82 additions and 71 deletions.
153 changes: 82 additions & 71 deletions arch/x86/kvm/x86.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1419,7 +1419,7 @@ EXPORT_SYMBOL_GPL(kvm_emulate_rdpmc);
* may depend on host virtualization features rather than host cpu features.
*/

static const u32 msrs_to_save_all[] = {
static const u32 msrs_to_save_base[] = {
MSR_IA32_SYSENTER_CS, MSR_IA32_SYSENTER_ESP, MSR_IA32_SYSENTER_EIP,
MSR_STAR,
#ifdef CONFIG_X86_64
Expand All @@ -1436,6 +1436,10 @@ static const u32 msrs_to_save_all[] = {
MSR_IA32_RTIT_ADDR3_A, MSR_IA32_RTIT_ADDR3_B,
MSR_IA32_UMWAIT_CONTROL,

MSR_IA32_XFD, MSR_IA32_XFD_ERR,
};

static const u32 msrs_to_save_pmu[] = {
MSR_ARCH_PERFMON_FIXED_CTR0, MSR_ARCH_PERFMON_FIXED_CTR1,
MSR_ARCH_PERFMON_FIXED_CTR0 + 2,
MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS,
Expand All @@ -1460,11 +1464,10 @@ static const u32 msrs_to_save_all[] = {
MSR_F15H_PERF_CTL3, MSR_F15H_PERF_CTL4, MSR_F15H_PERF_CTL5,
MSR_F15H_PERF_CTR0, MSR_F15H_PERF_CTR1, MSR_F15H_PERF_CTR2,
MSR_F15H_PERF_CTR3, MSR_F15H_PERF_CTR4, MSR_F15H_PERF_CTR5,

MSR_IA32_XFD, MSR_IA32_XFD_ERR,
};

static u32 msrs_to_save[ARRAY_SIZE(msrs_to_save_all)];
static u32 msrs_to_save[ARRAY_SIZE(msrs_to_save_base) +
ARRAY_SIZE(msrs_to_save_pmu)];
static unsigned num_msrs_to_save;

static const u32 emulated_msrs_all[] = {
Expand Down Expand Up @@ -6994,84 +6997,92 @@ long kvm_arch_vm_ioctl(struct file *filp,
return r;
}

static void kvm_init_msr_list(void)
static void kvm_probe_msr_to_save(u32 msr_index)
{
u32 dummy[2];

if (rdmsr_safe(msr_index, &dummy[0], &dummy[1]))
return;

/*
* Even MSRs that are valid in the host may not be exposed to guests in
* some cases.
*/
switch (msr_index) {
case MSR_IA32_BNDCFGS:
if (!kvm_mpx_supported())
return;
break;
case MSR_TSC_AUX:
if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP) &&
!kvm_cpu_cap_has(X86_FEATURE_RDPID))
return;
break;
case MSR_IA32_UMWAIT_CONTROL:
if (!kvm_cpu_cap_has(X86_FEATURE_WAITPKG))
return;
break;
case MSR_IA32_RTIT_CTL:
case MSR_IA32_RTIT_STATUS:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT))
return;
break;
case MSR_IA32_RTIT_CR3_MATCH:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
!intel_pt_validate_hw_cap(PT_CAP_cr3_filtering))
return;
break;
case MSR_IA32_RTIT_OUTPUT_BASE:
case MSR_IA32_RTIT_OUTPUT_MASK:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
(!intel_pt_validate_hw_cap(PT_CAP_topa_output) &&
!intel_pt_validate_hw_cap(PT_CAP_single_range_output)))
return;
break;
case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
(msr_index - MSR_IA32_RTIT_ADDR0_A >=
intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2))
return;
break;
case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR_MAX:
if (msr_index - MSR_ARCH_PERFMON_PERFCTR0 >=
kvm_pmu_cap.num_counters_gp)
return;
break;
case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL_MAX:
if (msr_index - MSR_ARCH_PERFMON_EVENTSEL0 >=
kvm_pmu_cap.num_counters_gp)
return;
break;
case MSR_IA32_XFD:
case MSR_IA32_XFD_ERR:
if (!kvm_cpu_cap_has(X86_FEATURE_XFD))
return;
break;
default:
break;
}

msrs_to_save[num_msrs_to_save++] = msr_index;
}

static void kvm_init_msr_list(void)
{
unsigned i;

BUILD_BUG_ON_MSG(KVM_PMC_MAX_FIXED != 3,
"Please update the fixed PMCs in msrs_to_saved_all[]");
"Please update the fixed PMCs in msrs_to_save_pmu[]");

num_msrs_to_save = 0;
num_emulated_msrs = 0;
num_msr_based_features = 0;

for (i = 0; i < ARRAY_SIZE(msrs_to_save_all); i++) {
if (rdmsr_safe(msrs_to_save_all[i], &dummy[0], &dummy[1]) < 0)
continue;

/*
* Even MSRs that are valid in the host may not be exposed
* to the guests in some cases.
*/
switch (msrs_to_save_all[i]) {
case MSR_IA32_BNDCFGS:
if (!kvm_mpx_supported())
continue;
break;
case MSR_TSC_AUX:
if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP) &&
!kvm_cpu_cap_has(X86_FEATURE_RDPID))
continue;
break;
case MSR_IA32_UMWAIT_CONTROL:
if (!kvm_cpu_cap_has(X86_FEATURE_WAITPKG))
continue;
break;
case MSR_IA32_RTIT_CTL:
case MSR_IA32_RTIT_STATUS:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT))
continue;
break;
case MSR_IA32_RTIT_CR3_MATCH:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
!intel_pt_validate_hw_cap(PT_CAP_cr3_filtering))
continue;
break;
case MSR_IA32_RTIT_OUTPUT_BASE:
case MSR_IA32_RTIT_OUTPUT_MASK:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
(!intel_pt_validate_hw_cap(PT_CAP_topa_output) &&
!intel_pt_validate_hw_cap(PT_CAP_single_range_output)))
continue;
break;
case MSR_IA32_RTIT_ADDR0_A ... MSR_IA32_RTIT_ADDR3_B:
if (!kvm_cpu_cap_has(X86_FEATURE_INTEL_PT) ||
msrs_to_save_all[i] - MSR_IA32_RTIT_ADDR0_A >=
intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2)
continue;
break;
case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR_MAX:
if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_PERFCTR0 >=
kvm_pmu_cap.num_counters_gp)
continue;
break;
case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL_MAX:
if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_EVENTSEL0 >=
kvm_pmu_cap.num_counters_gp)
continue;
break;
case MSR_IA32_XFD:
case MSR_IA32_XFD_ERR:
if (!kvm_cpu_cap_has(X86_FEATURE_XFD))
continue;
break;
default:
break;
}
for (i = 0; i < ARRAY_SIZE(msrs_to_save_base); i++)
kvm_probe_msr_to_save(msrs_to_save_base[i]);

msrs_to_save[num_msrs_to_save++] = msrs_to_save_all[i];
}
for (i = 0; i < ARRAY_SIZE(msrs_to_save_pmu); i++)
kvm_probe_msr_to_save(msrs_to_save_pmu[i]);

for (i = 0; i < ARRAY_SIZE(emulated_msrs_all); i++) {
if (!static_call(kvm_x86_has_emulated_msr)(NULL, emulated_msrs_all[i]))
Expand Down

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