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@xxxxxxxxxxxxxx>
> ---
> 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
>
> --
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--
Gleb.
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