| Message ID | 20230602073857.96790-1-gaoshiyuan@baidu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kvm: limit the maximum CPUID.0xA.edx[0..4] to 3 | expand |
Anyone has suggestion?
When the host kernel before this commit 2e8cd7a3b828 ("kvm: x86: limit the maximum number of vPMU
fixed counters to 3") on icelake microarchitecture and newer, execute cpuid in the Guest:
Architecture Performance Monitoring Features (0xa/edx):
number of fixed counters = 0x4 (4)
This is not inconsistent with num_architectural_pmu_fixed_counters in QEMU.
> Anyone has suggestion? > > When the host kernel before this commit 2e8cd7a3b828 ("kvm: x86: limit the maximum number of vPMU > fixed counters to 3") on icelake microarchitecture and newer, execute cpuid in the Guest: > > Architecture Performance Monitoring Features (0xa/edx): > number of fixed counters = 0x4 (4) > > This is not inconsistent with num_architectural_pmu_fixed_counters in QEMU. This is the orginal patch. kvm: limit the maximum CPUID.0xA.edx[0..4] to 3 Now, the CPUID.0xA depends on the KVM report. The value of CPUID.0xA.edx[0..4] and num_architectural_pmu_fixed_counters are inconsistent when the host kernel before this commit 2e8cd7a3b828 ("kvm: x86: limit the maximum number of vPMU fixed counters to 3") on icelake microarchitecture. This also break the live-migration between source host kernel before commit 2e8cd7a3b828 and dest host kernel after the commit on icelake microarchitecture. Signed-off-by: Shiyuan Gao <gaoshiyuan@baidu.com> --- target/i386/kvm/kvm.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index de531842f6..e77129b737 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -1761,7 +1761,7 @@ int kvm_arch_init_vcpu(CPUState *cs) X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; - uint32_t limit, i, j, cpuid_i; + uint32_t limit, i, j, cpuid_i, cpuid_0xa; uint32_t unused; struct kvm_cpuid_entry2 *c; uint32_t signature[3]; @@ -1773,6 +1773,7 @@ int kvm_arch_init_vcpu(CPUState *cs) memset(&cpuid_data, 0, sizeof(cpuid_data)); cpuid_i = 0; + cpuid_0xa = 0; has_xsave2 = kvm_check_extension(cs->kvm_state, KVM_CAP_XSAVE2); @@ -2045,6 +2046,9 @@ int kvm_arch_init_vcpu(CPUState *cs) c->function = i; c->flags = 0; cpu_x86_cpuid(env, i, 0, &c->eax, &c->ebx, &c->ecx, &c->edx); + if (0x0a == i) { + cpuid_0xa = cpuid_i - 1; + } if (!c->eax && !c->ebx && !c->ecx && !c->edx) { /* * KVM already returns all zeroes if a CPUID entry is missing, @@ -2059,7 +2063,11 @@ int kvm_arch_init_vcpu(CPUState *cs) if (limit >= 0x0a) { uint32_t eax, edx; - cpu_x86_cpuid(env, 0x0a, 0, &eax, &unused, &unused, &edx); + assert(cpuid_0xa >= 0x0a); + + c = &cpuid_data.entries[cpuid_0xa]; + eax = c->eax; + edx = c->edx; has_architectural_pmu_version = eax & 0xff; if (has_architectural_pmu_version > 0) { @@ -2078,6 +2086,7 @@ int kvm_arch_init_vcpu(CPUState *cs) if (num_architectural_pmu_fixed_counters > MAX_FIXED_COUNTERS) { num_architectural_pmu_fixed_counters = MAX_FIXED_COUNTERS; + c->edx = (edx & ~0x1f) | num_architectural_pmu_fixed_counters; } } }
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index de531842f6..e77129b737 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -1761,7 +1761,7 @@ int kvm_arch_init_vcpu(CPUState *cs) X86CPU *cpu = X86_CPU(cs); CPUX86State *env = &cpu->env; - uint32_t limit, i, j, cpuid_i; + uint32_t limit, i, j, cpuid_i, cpuid_0xa; uint32_t unused; struct kvm_cpuid_entry2 *c; uint32_t signature[3]; @@ -1773,6 +1773,7 @@ int kvm_arch_init_vcpu(CPUState *cs) memset(&cpuid_data, 0, sizeof(cpuid_data)); cpuid_i = 0; + cpuid_0xa = 0; has_xsave2 = kvm_check_extension(cs->kvm_state, KVM_CAP_XSAVE2); @@ -2045,6 +2046,9 @@ int kvm_arch_init_vcpu(CPUState *cs) c->function = i; c->flags = 0; cpu_x86_cpuid(env, i, 0, &c->eax, &c->ebx, &c->ecx, &c->edx); + if (0x0a == i) { + cpuid_0xa = cpuid_i - 1; + } if (!c->eax && !c->ebx && !c->ecx && !c->edx) { /* * KVM already returns all zeroes if a CPUID entry is missing, @@ -2059,7 +2063,11 @@ int kvm_arch_init_vcpu(CPUState *cs) if (limit >= 0x0a) { uint32_t eax, edx; - cpu_x86_cpuid(env, 0x0a, 0, &eax, &unused, &unused, &edx); + assert(cpuid_0xa >= 0x0a); + + c = &cpuid_data.entries[cpuid_0xa]; + eax = c->eax; + edx = c->edx; has_architectural_pmu_version = eax & 0xff; if (has_architectural_pmu_version > 0) { @@ -2078,6 +2086,7 @@ int kvm_arch_init_vcpu(CPUState *cs) if (num_architectural_pmu_fixed_counters > MAX_FIXED_COUNTERS) { num_architectural_pmu_fixed_counters = MAX_FIXED_COUNTERS; + c->edx = (edx & ~0x1f) | num_architectural_pmu_fixed_counters; } } }
Now, the CPUID.0xA depends on the KVM report. The value of CPUID.0xA.edx[0..4] and num_architectural_pmu_fixed_counters are inconsistent when the host kernel before this commit 2e8cd7a3b828 ("kvm: x86: limit the maximum number of vPMU fixed counters to 3") on icelake microarchitecture. This also break the live-migration between source host kernel before commit 2e8cd7a3b828 and dest host kernel after the commit on icelake microarchitecture. Signed-off-by: Shiyuan Gao <gaoshiyuan@baidu.com> --- target/i386/kvm/kvm.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)