Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934747Ab3FSNAJ (ORCPT ); Wed, 19 Jun 2013 09:00:09 -0400 Received: from e23smtp05.au.ibm.com ([202.81.31.147]:34246 "EHLO e23smtp05.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933869Ab3FSNAH (ORCPT ); Wed, 19 Jun 2013 09:00:07 -0400 Message-ID: <51C1AB4E.5020402@linux.vnet.ibm.com> Date: Wed, 19 Jun 2013 20:59:58 +0800 From: Xiao Guangrong User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130510 Thunderbird/17.0.6 MIME-Version: 1.0 To: Paolo Bonzini CC: gleb@redhat.com, avi.kivity@gmail.com, mtosatti@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 4/7] KVM: MMU: document mmio page fault References: <1371632965-20077-1-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <1371632965-20077-5-git-send-email-xiaoguangrong@linux.vnet.ibm.com> <51C19FC6.9020001@redhat.com> In-Reply-To: <51C19FC6.9020001@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13061912-1396-0000-0000-000003244E6B Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2596 Lines: 55 On 06/19/2013 08:10 PM, Paolo Bonzini wrote: > Il 19/06/2013 11:09, Xiao Guangrong ha scritto: >> Document it to Documentation/virtual/kvm/mmu.txt >> >> Signed-off-by: Xiao Guangrong >> --- >> Documentation/virtual/kvm/mmu.txt | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/virtual/kvm/mmu.txt b/Documentation/virtual/kvm/mmu.txt >> index 5a6b2e2..4fb442b 100644 >> --- a/Documentation/virtual/kvm/mmu.txt >> +++ b/Documentation/virtual/kvm/mmu.txt >> @@ -270,14 +270,21 @@ This is the most complicated event. The cause of a page fault can be: >> >> Handling a page fault is performed as follows: >> >> + - if the RSV bit of the error code is set, the page fault is caused by guest >> + accessing MMIO, walk shadow page table to get the last spte where the mmio >> + information is stored and cache the information to vcpu->arch.mmio_gva, >> + vcpu->arch.access and vcpu->arch.mmio_gfn then call the emulator to emulate >> + the instruction who will get the benefit from the cached mmio info > > + - if the RSV bit of the error code is set, the page fault is caused by guest > + accessing MMIO and cached MMIO information is available. > + - walk shadow page table > + - cache the information to vcpu->arch.mmio_gva, vcpu->arch.access and > + vcpu->arch.mmio_gfn, and call the emulator Nice. > >> - if needed, walk the guest page tables to determine the guest translation >> (gva->gpa or ngpa->gpa) >> - if permissions are insufficient, reflect the fault back to the guest >> - determine the host page >> - - if this is an mmio request, there is no host page; call the emulator >> - to emulate the instruction instead >> + - if this is an mmio request, there is no host page; cache the info to >> + vcpu->arch.mmio_gva, vcpu->arch.access and vcpu->arch.mmio_gfn >> - walk the shadow page table to find the spte for the translation, >> instantiating missing intermediate page tables as necessary >> + - If this is an mmio request, cache the mmio info to the spte and set some >> + reserved bits on the spte > > Added "(see callers of kvm_mmu_set_mmio_spte_mask)". Not really related, but > just came to my mind: perhaps we can have a section on A/D bits too. It is useful i think. Will do it. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/