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Commit 78c0337a authored by Marcelo Tosatti's avatar Marcelo Tosatti
Browse files

KVM: x86: retain pvclock guest stopped bit in guest memory 



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: default avatarGleb Natapov <gleb@redhat.com>
Reviewed-by: default avatarGlauber Costa <glommer@parallels.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 807f12e5

arch/x86/kvm/x86.c

+13 −7
Original line number Diff line number Diff line
@@ -1145,6 +1145,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) 
	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 */
@@ -1228,13 +1229,6 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) 
	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
@@ -1245,6 +1239,18 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) 


	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));