From: Gleb Natapov <gleb@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, mingo@elte.hu,
a.p.zijlstra@chello.nl, tglx@linutronix.de, hpa@zytor.com,
riel@redhat.com
Subject: Re: [PATCH v2 09/12] Retry fault before vmentry
Date: Wed, 25 Nov 2009 15:20:14 +0200 [thread overview]
Message-ID: <20091125132014.GO2999@redhat.com> (raw)
In-Reply-To: <4B0D2C90.2060200@redhat.com>
On Wed, Nov 25, 2009 at 03:09:36PM +0200, Avi Kivity wrote:
> On 11/23/2009 04:06 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.
> >
> >
> >-static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
> >+static int tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t cr3, gva_t gpa,
> > u32 error_code)
> > {
> > pfn_t pfn;
> >@@ -2230,7 +2233,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa,
> > mmu_seq = vcpu->kvm->mmu_notifier_seq;
> > smp_rmb();
> >
> >- if (can_do_async_pf(vcpu)) {
> >+ if (cr3 == vcpu->arch.cr3&& can_do_async_pf(vcpu)) {
>
> Why check cr3 here?
>
If cr3 == vcpu->arch.cr3 here we know that this is guest generated page
fault so we try to do it async. Otherwise this is async page fault code
try to establish mapping, so need to go through async logic.
Theoretically page that was just swapped in can be swapped out once again at
this point and in this case we need to go to sleep here otherwise things
may go wrong.
> >-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)
>
> I'd be slightly happier if we had a page_fault_other_cr3() op that
> switched cr3, called the original, then switched back (the tdp
> version need not change anything).
>
> --
> error compiling committee.c: too many arguments to function
--
Gleb.
--
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next prev parent reply other threads:[~2009-11-25 13:20 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-23 14:05 [PATCH v2 00/12] KVM: Add asynchronous page fault for PV guest Gleb Natapov
2009-11-23 14:05 ` [PATCH v2 01/12] Move kvm_smp_prepare_boot_cpu() from kvmclock.c to kvm.c Gleb Natapov
2009-11-23 14:05 ` [PATCH v2 02/12] Add PV MSR to enable asynchronous page faults delivery Gleb Natapov
2009-11-25 12:32 ` Avi Kivity
2009-11-23 14:05 ` [PATCH v2 03/12] Add async PF initialization to PV guest Gleb Natapov
2009-11-23 14:05 ` [PATCH v2 04/12] Add "handle page fault" PV helper Gleb Natapov
2009-11-23 15:32 ` Peter Zijlstra
2009-11-23 14:06 ` [PATCH v2 05/12] Handle asynchronous page fault in a PV guest Gleb Natapov
2009-11-25 12:45 ` Avi Kivity
2009-11-23 14:06 ` [PATCH v2 06/12] Export __get_user_pages_fast Gleb Natapov
2009-11-23 14:06 ` [PATCH v2 07/12] Add get_user_pages() variant that fails if major fault is required Gleb Natapov
2009-11-23 14:06 ` [PATCH v2 08/12] Inject asynchronous page fault into a guest if page is swapped out Gleb Natapov
2009-11-25 13:03 ` Avi Kivity
2009-11-23 14:06 ` [PATCH v2 09/12] Retry fault before vmentry Gleb Natapov
2009-11-25 13:09 ` Avi Kivity
2009-11-25 13:20 ` Gleb Natapov [this message]
2009-11-23 14:06 ` [PATCH v2 10/12] Maintain preemptability count even for !CONFIG_PREEMPT kernels Gleb Natapov
2009-11-23 15:34 ` Peter Zijlstra
2009-11-23 15:58 ` Gleb Natapov
2009-11-23 17:30 ` Christoph Lameter
2009-11-24 7:12 ` Gleb Natapov
2009-11-24 15:14 ` Christoph Lameter
2009-11-30 10:56 ` Gleb Natapov
2009-11-30 10:58 ` Gleb Natapov
2009-11-30 10:59 ` Peter Zijlstra
2009-11-30 11:01 ` Avi Kivity
2009-11-30 11:05 ` Peter Zijlstra
2009-11-30 16:23 ` Christoph Lameter
2009-11-23 14:06 ` [PATCH v2 11/12] Handle async PF in non preemptable context Gleb Natapov
2009-11-23 14:06 ` [PATCH v2 12/12] Send async PF when guest is not in userspace too Gleb Natapov
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