* [PATCH] KVM: X86: Do not yield to self
@ 2021-04-08 11:23 Wanpeng Li
2021-04-08 16:56 ` Sean Christopherson
0 siblings, 1 reply; 3+ messages in thread
From: Wanpeng Li @ 2021-04-08 11:23 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Sean Christopherson, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
From: Wanpeng Li <wanpengli@tencent.com>
If the target is self we do not need to yield, we can avoid malicious
guest to play this.
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
Rebased on https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpengli@tencent.com/
arch/x86/kvm/x86.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 43c9f9b..260650f 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8230,6 +8230,10 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
if (!target)
goto no_yield;
+ /* yield to self */
+ if (vcpu->vcpu_id == target->vcpu_id)
+ goto no_yield;
+
if (!READ_ONCE(target->ready))
goto no_yield;
--
2.7.4
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: X86: Do not yield to self
2021-04-08 11:23 [PATCH] KVM: X86: Do not yield to self Wanpeng Li
@ 2021-04-08 16:56 ` Sean Christopherson
2021-04-09 3:05 ` Wanpeng Li
0 siblings, 1 reply; 3+ messages in thread
From: Sean Christopherson @ 2021-04-08 16:56 UTC (permalink / raw)
To: Wanpeng Li
Cc: linux-kernel, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Thu, Apr 08, 2021, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> If the target is self we do not need to yield, we can avoid malicious
> guest to play this.
>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> Rebased on https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpengli@tencent.com/
>
> arch/x86/kvm/x86.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 43c9f9b..260650f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8230,6 +8230,10 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
> if (!target)
> goto no_yield;
>
> + /* yield to self */
If you're going to bother with a comment, maybe elaborate a bit, e.g.
/* Ignore requests to yield to self. */
> + if (vcpu->vcpu_id == target->vcpu_id)
> + goto no_yield;
> +
> if (!READ_ONCE(target->ready))
> goto no_yield;
>
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: X86: Do not yield to self
2021-04-08 16:56 ` Sean Christopherson
@ 2021-04-09 3:05 ` Wanpeng Li
0 siblings, 0 replies; 3+ messages in thread
From: Wanpeng Li @ 2021-04-09 3:05 UTC (permalink / raw)
To: Sean Christopherson
Cc: LKML, kvm, Paolo Bonzini, Vitaly Kuznetsov, Wanpeng Li,
Jim Mattson, Joerg Roedel
On Fri, 9 Apr 2021 at 00:56, Sean Christopherson <seanjc@google.com> wrote:
>
> On Thu, Apr 08, 2021, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@tencent.com>
> >
> > If the target is self we do not need to yield, we can avoid malicious
> > guest to play this.
> >
> > Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> > ---
> > Rebased on https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpengli@tencent.com/
> >
> > arch/x86/kvm/x86.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 43c9f9b..260650f 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -8230,6 +8230,10 @@ static void kvm_sched_yield(struct kvm_vcpu *vcpu, unsigned long dest_id)
> > if (!target)
> > goto no_yield;
> >
> > + /* yield to self */
>
> If you're going to bother with a comment, maybe elaborate a bit, e.g.
>
> /* Ignore requests to yield to self. */
Looks good, thanks.
Wanpeng
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2021-04-09 3:06 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-04-08 11:23 [PATCH] KVM: X86: Do not yield to self Wanpeng Li
2021-04-08 16:56 ` Sean Christopherson
2021-04-09 3:05 ` Wanpeng Li
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).