From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 16/22] KVM: MMU: Track page fault data in struct vcpu Date: Tue, 27 Apr 2010 16:37:42 +0300 Message-ID: <4BD6E8A6.5040008@redhat.com> References: <1272364712-17425-1-git-send-email-joerg.roedel@amd.com> <1272364712-17425-17-git-send-email-joerg.roedel@amd.com> <4BD6DF7C.1090203@redhat.com> <20100427132801.GI11097@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Joerg Roedel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:53469 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753156Ab0D0Nhp (ORCPT ); Tue, 27 Apr 2010 09:37:45 -0400 In-Reply-To: <20100427132801.GI11097@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: On 04/27/2010 04:28 PM, Joerg Roedel wrote: > >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>> index d9dfc8c..8426870 100644 >>> --- a/arch/x86/include/asm/kvm_host.h >>> +++ b/arch/x86/include/asm/kvm_host.h >>> @@ -298,6 +298,9 @@ struct kvm_vcpu_arch { >>> /* Used for two dimensional paging emulation */ >>> struct kvm_mmu nested_mmu; >>> >>> + unsigned long fault_address; >>> >> Probably a problem on i386. How does npt handle faults when the >> guest is using pae paging and the host (in our case the guest...) >> isn't? I see it uses exit_info_2 for the address, which is a u64. >> > This shouldn't be an issue. If we run on 32bit host with nested paging > the guest can't have more than 4gb of addressable memory because of the > page table limitations (nested page table is always in host format). > But the nested guest can use pae paging and generate a #NPF with exit_info_2 > 4GB. So we need to keep the full fault address; if we truncate, the guest might actually resolve the fault and let the nested guest continue. -- error compiling committee.c: too many arguments to function