From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
There is a logic to handle first-time write when updating the
pvclock/wall clock/steal time shared memory pages each time,
actually we should do this logic during pv stuffs setup if we
suspect the version-field can't be guranteed to be initialized
to an even number by the guest. This patch fixes it by handling
the first-time write of pvclock/steal time during setup since
the update is frequent, and keeping the wall clock since it is
rare updating.
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Liran Alon <liran.alon@xxxxxxxxxx>
Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 29 ++++++++++++++++++++++-------
1 file changed, 22 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4552427..19311e0 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1833,9 +1833,6 @@ static void kvm_setup_pvclock_page(struct kvm_vcpu *v)
*/
BUILD_BUG_ON(offsetof(struct pvclock_vcpu_time_info, version) != 0);
- if (guest_hv_clock.version & 1)
- ++guest_hv_clock.version; /* first time write, random junk */
-
vcpu->hv_clock.version = guest_hv_clock.version + 1;
kvm_write_guest_cached(v->kvm, &vcpu->pv_time,
&vcpu->hv_clock,
@@ -2126,9 +2123,6 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
vcpu->arch.st.steal.preempted = 0;
- if (vcpu->arch.st.steal.version & 1)
- vcpu->arch.st.steal.version += 1; /* first time write, random junk */
-
vcpu->arch.st.steal.version += 1;
kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
@@ -2256,8 +2250,19 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
&vcpu->arch.pv_time, data & ~1ULL,
sizeof(struct pvclock_vcpu_time_info)))
vcpu->arch.pv_time_enabled = false;
- else
+ else {
+ struct pvclock_vcpu_time_info guest_hv_clock;
+
vcpu->arch.pv_time_enabled = true;
+ if (unlikely(kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.pv_time,
+ &guest_hv_clock, sizeof(guest_hv_clock))))
+ break;
+ if (guest_hv_clock.version & 1)
+ ++guest_hv_clock.version; /* first time write, random junk */
+ kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.pv_time,
+ &vcpu->arch.hv_clock,
+ sizeof(vcpu->arch.hv_clock.version));
+ }
break;
}
@@ -2283,6 +2288,16 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (!(data & KVM_MSR_ENABLED))
break;
+ if (unlikely(kvm_read_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
+ &vcpu->arch.st.steal, sizeof(struct kvm_steal_time))))
+ break;
+
+ if (vcpu->arch.st.steal.version & 1)
+ vcpu->arch.st.steal.version += 1; /* first time write, random junk */
+
+ kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.st.stime,
+ &vcpu->arch.st.steal, sizeof(struct kvm_steal_time));
+
kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
break;
--
2.7.4
