Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754419Ab0DZDNZ (ORCPT ); Sun, 25 Apr 2010 23:13:25 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:64783 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752697Ab0DZDNY (ORCPT ); Sun, 25 Apr 2010 23:13:24 -0400 Message-ID: <4BD50417.6090409@cn.fujitsu.com> Date: Mon, 26 Apr 2010 11:10:15 +0800 From: Xiao Guangrong User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Avi Kivity CC: Marcelo Tosatti , KVM list , LKML Subject: Re: [PATCH v2 1/10] KVM MMU: fix for calculating gpa in invlpg code References: <4BD3E306.4020202@cn.fujitsu.com> <4BD3E870.60000@cn.fujitsu.com> <4BD40F6D.3090002@redhat.com> In-Reply-To: <4BD40F6D.3090002@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1983 Lines: 55 Avi Kivity wrote: > On 04/25/2010 10:00 AM, Xiao Guangrong wrote: >> If the guest is 32-bit, we should use 'quadrant' to adjust gpa >> offset >> >> Changlog v2: >> - when level is PT_DIRECTORY_LEVEL, the 'offset' should be >> 'role.quadrant<< 8', thanks Avi for point it out >> >> Signed-off-by: Xiao Guangrong >> --- >> arch/x86/kvm/paging_tmpl.h | 13 +++++++++++-- >> 1 files changed, 11 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h >> index d0cc07e..83cc72f 100644 >> --- a/arch/x86/kvm/paging_tmpl.h >> +++ b/arch/x86/kvm/paging_tmpl.h >> @@ -478,9 +478,18 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, >> gva_t gva) >> ((level == PT_DIRECTORY_LEVEL&& is_large_pte(*sptep))) || >> ((level == PT_PDPE_LEVEL&& is_large_pte(*sptep)))) { >> struct kvm_mmu_page *sp = page_header(__pa(sptep)); >> - >> + int offset = 0; >> + >> + if (PTTYPE == 32) { >> + if (level == PT_DIRECTORY_LEVEL) >> + offset = PAGE_SHIFT - 4; >> + else >> + offset = PT64_LEVEL_BITS; >> + offset = sp->role.quadrant<< offset; >> + } >> > > The calculation is really > > shift = (PT32_LEVEL_BITS - PT64_LEVEL_BITS) * level; > So, the offset is q << (PAGE_SHIFT - (PT32_LEVEL_BITS - PT64_LEVEL_BITS) * level - 2)? As my origin thinking, for level = 2, one gfn has 4 shadow pages, so every shadow page occupies PAGE_SIZE / 4, and sizeof(pt_element_t) is 4 in 32-bit guest, so the offset is: q * (PAGE_SIZE/4/4) = q << (PAGE_SHIFT - 2 -2) Obviously, my code is really ugly than your :-) -- 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/