Otherwise its possible for an unrelated KVM_REQ_UPDATE_CLOCK (such as due to CPU
migration) to clear the bit.
Noticed by Paolo Bonzini.
Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx>
Reviewed-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Index: vsyscall/arch/x86/kvm/x86.c
===================================================================
--- vsyscall.orig/arch/x86/kvm/x86.c
+++ vsyscall/arch/x86/kvm/x86.c
@@ -1143,6 +1143,7 @@ static int kvm_guest_time_update(struct
unsigned long this_tsc_khz;
s64 kernel_ns, max_kernel_ns;
u64 tsc_timestamp;
+ struct pvclock_vcpu_time_info *guest_hv_clock;
u8 pvclock_flags;
/* Keep irq disabled to prevent changes to the clock */
@@ -1226,13 +1227,6 @@ static int kvm_guest_time_update(struct
vcpu->last_kernel_ns = kernel_ns;
vcpu->last_guest_tsc = tsc_timestamp;
- pvclock_flags = 0;
- if (vcpu->pvclock_set_guest_stopped_request) {
- pvclock_flags |= PVCLOCK_GUEST_STOPPED;
- vcpu->pvclock_set_guest_stopped_request = false;
- }
-
- vcpu->hv_clock.flags = pvclock_flags;
/*
* The interface expects us to write an even number signaling that the
@@ -1243,6 +1237,18 @@ static int kvm_guest_time_update(struct
shared_kaddr = kmap_atomic(vcpu->time_page);
+ guest_hv_clock = shared_kaddr + vcpu->time_offset;
+
+ /* retain PVCLOCK_GUEST_STOPPED if set in guest copy */
+ pvclock_flags = (guest_hv_clock->flags & PVCLOCK_GUEST_STOPPED);
+
+ if (vcpu->pvclock_set_guest_stopped_request) {
+ pvclock_flags |= PVCLOCK_GUEST_STOPPED;
+ vcpu->pvclock_set_guest_stopped_request = false;
+ }
+
+ vcpu->hv_clock.flags = pvclock_flags;
+
memcpy(shared_kaddr + vcpu->time_offset, &vcpu->hv_clock,
sizeof(vcpu->hv_clock));
--
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