From: Avi Kivity <avi@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 07/11] Retry fault before vmentry
Date: Mon, 02 Nov 2009 15:03:36 +0200 [thread overview]
Message-ID: <4AEED8A8.9030606@redhat.com> (raw)
In-Reply-To: <1257076590-29559-8-git-send-email-gleb@redhat.com>
On 11/01/2009 01:56 PM, Gleb Natapov wrote:
> When page is swapped in it is mapped into guest memory only after guest
> tries to access it again and generate another fault. To save this fault
> we can map it immediately since we know that guest is going to access
> the page.
>
>
>
> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
> index 9fe2ecd..b1fe61f 100644
> --- a/arch/x86/kvm/paging_tmpl.h
> +++ b/arch/x86/kvm/paging_tmpl.h
> @@ -375,7 +375,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
> * Returns: 1 if we need to emulate the instruction, 0 otherwise, or
> * a negative value on error.
> */
> -static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
> +static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t cr3, gva_t addr,
> u32 error_code)
> {
> int write_fault = error_code& PFERR_WRITE_MASK;
> @@ -388,6 +388,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
> pfn_t pfn;
> int level = PT_PAGE_TABLE_LEVEL;
> unsigned long mmu_seq;
> + gpa_t curr_cr3 = vcpu->arch.cr3;
>
> pgprintk("%s: addr %lx err %x\n", __func__, addr, error_code);
> kvm_mmu_audit(vcpu, "pre page fault");
> @@ -396,6 +397,13 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr,
> if (r)
> return r;
>
> + if (curr_cr3 != cr3) {
> + vcpu->arch.cr3 = cr3;
> + paging_new_cr3(vcpu);
> + if (kvm_mmu_reload(vcpu))
> + goto switch_cr3;
> + }
> +
>
This is a little frightening. I can't put my finger on anything
though. But playing with cr3 under the guest's feet worries me.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2009-11-02 13:03 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-01 11:56 [PATCH 00/11] KVM: Add asynchronous page fault for PV guest Gleb Natapov
2009-11-01 11:56 ` [PATCH 01/11] Add shared memory hypercall to PV Linux guest Gleb Natapov
2009-11-02 4:27 ` Rik van Riel
2009-11-02 7:07 ` Gleb Natapov
2009-11-02 12:18 ` Avi Kivity
2009-11-02 16:18 ` Gleb Natapov
2009-11-03 5:15 ` Avi Kivity
2009-11-03 7:16 ` Gleb Natapov
2009-11-03 7:40 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 02/11] Add "handle page fault" PV helper Gleb Natapov
2009-11-02 9:22 ` Ingo Molnar
2009-11-02 16:04 ` Gleb Natapov
2009-11-02 16:12 ` Ingo Molnar
2009-11-02 16:22 ` Gleb Natapov
2009-11-02 16:29 ` Ingo Molnar
2009-11-02 16:31 ` Gleb Natapov
2009-11-02 17:42 ` Gleb Natapov
2009-11-08 11:36 ` Ingo Molnar
2009-11-08 12:43 ` Avi Kivity
2009-11-08 12:51 ` Ingo Molnar
2009-11-08 13:01 ` Avi Kivity
2009-11-08 13:05 ` Ingo Molnar
2009-11-08 13:08 ` Avi Kivity
2009-11-08 16:44 ` H. Peter Anvin
2009-11-08 16:47 ` Ingo Molnar
2009-11-02 19:03 ` Rik van Riel
2009-11-02 19:33 ` Avi Kivity
2009-11-02 23:35 ` Rik van Riel
2009-11-03 4:57 ` Avi Kivity
2009-11-05 6:44 ` Tian, Kevin
2009-11-05 8:22 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 03/11] Handle asynchronous page fault in a PV guest Gleb Natapov
2009-11-02 12:38 ` Avi Kivity
2009-11-02 15:54 ` Gleb Natapov
2009-11-03 14:14 ` Marcelo Tosatti
2009-11-03 14:25 ` Gleb Natapov
2009-11-03 14:32 ` Marcelo Tosatti
2009-11-03 14:38 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 04/11] Export __get_user_pages_fast Gleb Natapov
2009-11-02 9:23 ` Ingo Molnar
2009-11-01 11:56 ` [PATCH 05/11] Add get_user_pages() variant that fails if major fault is required Gleb Natapov
2009-11-02 19:05 ` Rik van Riel
2009-11-01 11:56 ` [PATCH 06/11] Inject asynchronous page fault into a guest if page is swapped out Gleb Natapov
2009-11-02 12:56 ` Avi Kivity
2009-11-02 15:41 ` Gleb Natapov
2009-11-01 11:56 ` [PATCH 07/11] Retry fault before vmentry Gleb Natapov
2009-11-02 13:03 ` Avi Kivity [this message]
2009-11-01 11:56 ` [PATCH 08/11] Add "wait for page" hypercall Gleb Natapov
2009-11-02 13:05 ` Avi Kivity
2009-11-02 15:13 ` Gleb Natapov
2009-11-02 15:19 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 09/11] Maintain preemptability count even for !CONFIG_PREEMPT kernels Gleb Natapov
2009-11-02 9:24 ` Ingo Molnar
2009-11-01 11:56 ` [PATCH 10/11] Handle async PF in non preemptable context Gleb Natapov
2009-11-01 11:56 ` [PATCH 11/11] Send async PF when guest is not in userspace too Gleb Natapov
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