From 78c0337a38450f809113dd46fe038874b93909f1 Mon Sep 17 00:00:00 2001 From: Marcelo Tosatti Date: Tue, 27 Nov 2012 23:28:47 -0200 Subject: [PATCH] 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: Gleb Natapov Reviewed-by: Glauber Costa Signed-off-by: Marcelo Tosatti --- arch/x86/kvm/x86.c | 20 +++++++++++++------- 1 file changed, 13 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index c31f75d..1dfe9d3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -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)); -- 2.7.4