Re: [PATCH] KVM: X86: Do not yield to self
On Fri, 9 Apr 2021 at 00:56, Sean Christopherson wrote: > > On Thu, Apr 08, 2021, Wanpeng Li wrote: > > From: Wanpeng Li > > > > If the target is self we do not need to yield, we can avoid malicious > > guest to play this. > > > > Signed-off-by: Wanpeng Li > > --- > > Rebased on > > https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpen...@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
Re: [PATCH] KVM: X86: Do not yield to self
On Thu, Apr 08, 2021, Wanpeng Li wrote: > From: Wanpeng Li > > If the target is self we do not need to yield, we can avoid malicious > guest to play this. > > Signed-off-by: Wanpeng Li > --- > Rebased on > https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpen...@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 >
[PATCH] KVM: X86: Do not yield to self
From: Wanpeng Li If the target is self we do not need to yield, we can avoid malicious guest to play this. Signed-off-by: Wanpeng Li --- Rebased on https://lore.kernel.org/kvm/1617697935-4158-1-git-send-email-wanpen...@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
