From: Shiyuan Gao <gaoshiyuan@xxxxxxxxx>
When live-migrate VM on icelake microarchitecture, if the source
host kernel before commit 2e8cd7a3b828 ("kvm: x86: limit the maximum
number of vPMU fixed counters to 3") and the dest host kernel after this
commit, the migration will fail.
The source VM's CPUID.0xA.edx[0..4]=4 that is reported by KVM and
the IA32_PERF_GLOBAL_CTRL MSR is 0xf000000ff. However the dest VM's
CPUID.0xA.edx[0..4]=3 and the IA32_PERF_GLOBAL_CTRL MSR is 0x7000000ff.
This inconsistency leads to migration failure.
The QEMU limits the maximum number of vPMU fixed counters to 3, so ignore
the check of IA32_PERF_GLOBAL_CTRL bit35.
Fixes: 2e8cd7a3b828 ("kvm: x86: limit the maximum number of vPMU fixed counters to 3")
Signed-off-by: Shiyuan Gao <gaoshiyuan@xxxxxxxxx>
---
arch/x86/kvm/pmu.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 5c7bbf03b599..9895311d334e 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -91,7 +91,7 @@ static inline bool pmc_is_fixed(struct kvm_pmc *pmc)
static inline bool kvm_valid_perf_global_ctrl(struct kvm_pmu *pmu,
u64 data)
{
- return !(pmu->global_ctrl_mask & data);
+ return !(pmu->global_ctrl_mask & (data & ~(1ULL << 35)));
}
/* returns general purpose PMC with the specified MSR. Note that it can be
--
2.36.1
