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KVM: VMX: Fix delayed load of shared MSRs 

Shared MSRs (MSR_*STAR and related) are stored in both vmx->guest_msrs
and in the CPU registers, but vmx_set_msr() only updated memory. Prior
to 46199f33c2, this didn't matter, since we called vmx_load_host_state(),
which scheduled a vmx_save_host_state(), which re-synchronized the CPU
state, but now we don't, so the CPU state will not be synchronized until
the next exit to host userspace.  This mostly affects nested vmx workloads,
which play with these MSRs a lot.

Fix by loading the MSR eagerly.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2012-03-06 14:16:33 +02:00
parent bec87d6e34
commit 9ee73970c0
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/vmx.c
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@ -2210,6 +2210,9 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
msr = find_msr_entry(vmx, msr_index); msr = find_msr_entry(vmx, msr_index);
if (msr) { if (msr) {
msr->data = data; msr->data = data;
if (msr - vmx->guest_msrs < vmx->save_nmsrs)
kvm_set_shared_msr(msr->index, msr->data,
msr->mask);
break; break;
} }
ret = kvm_set_msr_common(vcpu, msr_index, data); ret = kvm_set_msr_common(vcpu, msr_index, data);