From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753426AbbDHIuX (ORCPT ); Wed, 8 Apr 2015 04:50:23 -0400 Received: from mail-wi0-f178.google.com ([209.85.212.178]:38848 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751506AbbDHIuD (ORCPT ); Wed, 8 Apr 2015 04:50:03 -0400 Message-ID: <5524EBB7.3080906@redhat.com> Date: Wed, 08 Apr 2015 10:49:59 +0200 From: Paolo Bonzini User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel@vger.kernel.org CC: kvm@vger.kernel.org Subject: Re: [PATCH] KVM: dirty all pages in kvm_write_guest_cached() References: <1428438897-22206-1-git-send-email-rkrcmar@redhat.com> In-Reply-To: <1428438897-22206-1-git-send-email-rkrcmar@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/04/2015 22:34, Radim Krčmář wrote: > We dirtied only one page because writes originally couldn't span more. > Use improved syntax for '>> PAGE_SHIFT' while at it. > > Fixes: 8f964525a121 ("KVM: Allow cross page reads and writes from cached translations.") > Signed-off-by: Radim Krčmář Cross-page reads and writes should never get here; they have ghc->memslot set to NULL and go through the slow path in kvm_write_guest. What am I missing? Paolo > --- > The function handles cross memslot writes in a different path. > > I think we should dirty pages after partial writes too (r < len), > but it probably won't happen and I already started refactoring :) > > virt/kvm/kvm_main.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index aadef264bed1..863df9dcab6f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1665,6 +1665,7 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > { > struct kvm_memslots *slots = kvm_memslots(kvm); > int r; > + gfn_t gfn; > > BUG_ON(len > ghc->len); > > @@ -1680,7 +1681,10 @@ int kvm_write_guest_cached(struct kvm *kvm, struct gfn_to_hva_cache *ghc, > r = __copy_to_user((void __user *)ghc->hva, data, len); > if (r) > return -EFAULT; > - mark_page_dirty_in_slot(kvm, ghc->memslot, ghc->gpa >> PAGE_SHIFT); > + > + for (gfn = gpa_to_gfn(ghc->gpa); > + gfn <= gpa_to_gfn(ghc->gpa + len - 1); gfn++) > + mark_page_dirty_in_slot(kvm, ghc->memslot, gfn); > > return 0; > } >