On Fri, May 28, 2021, Ilias Stamatis wrote:
> @@ -10343,8 +10360,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> else
> vcpu->arch.mp_state = KVM_MP_STATE_UNINITIALIZED;
>
> - kvm_set_tsc_khz(vcpu, max_tsc_khz);
> -
> r = kvm_mmu_create(vcpu);
> if (r < 0)
> return r;
> @@ -10443,6 +10458,7 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> if (mutex_lock_killable(&vcpu->mutex))
> return;
> vcpu_load(vcpu);
> + kvm_set_tsc_khz(vcpu, max_tsc_khz);
It would be safer to move the call within kvm_arch_vcpu_create(), not to
postcreate(). postcreate() runs after the vCPU file descriptor is exposed to
userspace, e.g. KVM_GET_TSC_KHZ could theoretically read the wrong value. I
don't know if there's anything more sinister that could be done, but I also
don't see any reason to find out :-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bc6160db94b1..08f6b8f82506 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10291,8 +10291,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
else
vcpu->arch.mp_state = KVM_MP_STATE_UNINITIALIZED;
- kvm_set_tsc_khz(vcpu, max_tsc_khz);
-
r = kvm_mmu_create(vcpu);
if (r < 0)
return r;
@@ -10360,6 +10358,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.msr_platform_info = MSR_PLATFORM_INFO_CPUID_FAULT;
kvm_vcpu_mtrr_init(vcpu);
vcpu_load(vcpu);
+ kvm_set_tsc_khz(vcpu, max_tsc_khz);
kvm_vcpu_reset(vcpu, false);
kvm_init_mmu(vcpu, false);
vcpu_put(vcpu);
> kvm_synchronize_tsc(vcpu, 0);
> vcpu_put(vcpu);
>
> --
> 2.17.1
>
