From: Gleb Natapov <gleb@redhat.com>
To: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
LKML <linux-kernel@vger.kernel.org>, KVM <kvm@vger.kernel.org>
Subject: Re: [PATCH 5/8] KVM: don't touch vcpu stat after async pf is complete
Date: Wed, 27 Oct 2010 12:44:12 +0200 [thread overview]
Message-ID: <20101027104412.GO26191@redhat.com> (raw)
In-Reply-To: <4CC7EB75.9030709@cn.fujitsu.com>
On Wed, Oct 27, 2010 at 05:05:57PM +0800, Xiao Guangrong wrote:
> Don't make a KVM_REQ_UNHALT request after async pf is completed since it
> can break guest's 'halt' instruction.
>
Why is it a problem? CPU may be unhalted by different events so OS
shouldn't depend on it.
> Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/x86.c | 5 +++++
> virt/kvm/async_pf.c | 1 +
> virt/kvm/kvm_main.c | 7 +++++--
> 4 files changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 1be0058..d01677b 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -822,6 +822,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
> struct kvm_async_pf *work);
> void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu,
> struct kvm_async_pf *work);
> +void kvm_arch_async_pf_completion(struct kvm_vcpu *vcpu);
> bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu);
> extern bool kvm_find_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn);
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 0b2c420..c0e7ad0 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6280,6 +6280,11 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
> }
> }
>
> +void kvm_arch_async_pf_completion(struct kvm_vcpu *vcpu)
> +{
> + vcpu->arch.apf.halted = false;
> +}
> +
> bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
> {
> if (!(vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED))
> diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
> index e213ca4..5307a32 100644
> --- a/virt/kvm/async_pf.c
> +++ b/virt/kvm/async_pf.c
> @@ -142,6 +142,7 @@ bool kvm_check_async_pf_completion(struct kvm_vcpu *vcpu)
> if (work->page)
> put_page(work->page);
> kmem_cache_free(async_pf_cache, work);
> + kvm_arch_async_pf_completion(vcpu);
>
> return true;
> }
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index d9aed28..23a8b06 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1347,11 +1347,14 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
> for (;;) {
> prepare_to_wait(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);
>
> - if (kvm_arch_vcpu_runnable(vcpu) ||
> - kvm_check_async_pf_completion(vcpu)) {
> + if (kvm_arch_vcpu_runnable(vcpu)) {
> kvm_make_request(KVM_REQ_UNHALT, vcpu);
> break;
> }
> +
> + if (kvm_check_async_pf_completion(vcpu))
> + break;
> +
> if (kvm_cpu_has_pending_timer(vcpu))
> break;
> if (signal_pending(current))
> --
> 1.7.0.4
>
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
--
Gleb.
next prev parent reply other threads:[~2010-10-27 10:47 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-27 9:01 [PATCH 1/8] KVM: fix tracing kvm_try_async_get_page Xiao Guangrong
2010-10-27 9:02 ` [PATCH 2/8] KVM: cleanup aysnc_pf tracepoints Xiao Guangrong
2010-10-27 10:10 ` Gleb Natapov
2010-10-27 9:03 ` [PATCH 3/8] KVM: fix searching async gfn in kvm_async_pf_gfn_slot Xiao Guangrong
2010-10-27 10:29 ` Gleb Natapov
2010-10-27 9:04 ` [PATCH 4/8] KVM: avoid unnecessary wait for a async pf Xiao Guangrong
2010-10-27 10:42 ` Gleb Natapov
2010-10-28 7:06 ` Xiao Guangrong
2010-10-27 9:05 ` [PATCH 5/8] KVM: don't touch vcpu stat after async pf is complete Xiao Guangrong
2010-10-27 10:44 ` Gleb Natapov [this message]
2010-10-28 7:35 ` Xiao Guangrong
2010-10-28 7:41 ` Gleb Natapov
2010-10-27 9:07 ` [PATCH 6/8] KVM: simply wakup async pf Xiao Guangrong
2010-10-27 10:50 ` Gleb Natapov
2010-10-28 7:59 ` Xiao Guangrong
2010-10-27 9:09 ` [PATCH 7/8] KVM: make async_pf work queue lockless Xiao Guangrong
2010-10-27 11:41 ` Gleb Natapov
2010-10-28 9:08 ` Xiao Guangrong
2010-10-28 9:14 ` Gleb Natapov
2010-10-27 9:10 ` [PATCH 8/8] KVM: add debugfs file to show the number of async pf Xiao Guangrong
2010-10-27 10:58 ` Gleb Natapov
2010-10-28 9:09 ` Xiao Guangrong
2010-10-27 9:59 ` [PATCH 1/8] KVM: fix tracing kvm_try_async_get_page Gleb Natapov
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