On Wed, Oct 31, 2012 at 08:46:57PM -0200, Marcelo Tosatti wrote:
> Otherwise its possible for an unrelated KVM_REQ_UPDATE_CLOCK (such as due to CPU
> migration) to clear the bit.
>
> Noticed by Paolo Bonzini.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>
Reviewed-by: Gleb Natapov <gleb@xxxxxxxxxx>
Small nitpick bellow.
Also do we really need to call kvm_guest_time_update() on a guest pause?
Wouldn't separate request bit, which only sets the flag, suffice?
> 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,
We can use guest_hv_clock here now.
> sizeof(vcpu->hv_clock));
>
>
--
Gleb.
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