[PATCH] call write_guest_time as soon as we register the paravirt clock.

[PATCH] call write_guest_time as soon as we register the paravirt clock.

[Glauber de Oliveira Costa]

From: Glauber Costa <gcosta@redhat.com>

In situations, like, cpu hotplugging, a cpu can arrive
later on the game and register its paravirt clock
while everything else is already running, which will lead to
breakage, since the time readings will return bogus values.

To prevent this, we write system time as soon as the guest
registers its clock

Signed-off-by: Glauber Costa <gcosta@redhat.com>
---
 arch/x86/kvm/x86.c |    2 ++
 1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5dfc21f..03c0c6d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -595,6 +595,8 @@ int kvm_set_msr_common(struct kvm_vcpu *
 
 		if (is_error_page(vcpu->arch.time_page))
 			vcpu->arch.time_page = NULL;
+
+		kvm_write_guest_time(vcpu);
 		break;
 	}
 	default:
-- 
1.4.2


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Re: [PATCH] call write_guest_time as soon as we register the paravirt clock.

[Avi Kivity]

Glauber de Oliveira Costa wrote:
> From: Glauber Costa <gcosta@redhat.com>
>
> In situations, like, cpu hotplugging, a cpu can arrive
> later on the game and register its paravirt clock
> while everything else is already running, which will lead to
> breakage, since the time readings will return bogus values.
>
> To prevent this, we write system time as soon as the guest
> registers its clock
>   

Applied, thanks.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.


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