Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760007AbaGDGlK (ORCPT ); Fri, 4 Jul 2014 02:41:10 -0400 Received: from cn.fujitsu.com ([59.151.112.132]:53558 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1752175AbaGDGlG (ORCPT ); Fri, 4 Jul 2014 02:41:06 -0400 X-IronPort-AV: E=Sophos;i="5.00,830,1396972800"; d="scan'208";a="32833660" Message-ID: <53B64CB5.4080203@cn.fujitsu.com> Date: Fri, 4 Jul 2014 14:41:57 +0800 From: Tang Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Gleb Natapov CC: , , , , , , Tang Chen Subject: Re: [PATCH 0/4] kvm, mem-hotplug: Do not pin ept identity pagetable and apic access page. References: <1404291637-15048-1-git-send-email-tangchen@cn.fujitsu.com> <53B4AF47.1080008@cn.fujitsu.com> <20140703060409.GL18167@minantech.com> In-Reply-To: <20140703060409.GL18167@minantech.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.99] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Gleb, On 07/03/2014 02:04 PM, Gleb Natapov wrote: > On Thu, Jul 03, 2014 at 09:17:59AM +0800, Tang Chen wrote: >> Hi Gleb, >> >> On 07/02/2014 05:00 PM, Tang Chen wrote: >>> Hi Gleb, Marcelo, >>> >>> Please help to review this patch-set. >>> >>> NOTE: This patch-set doesn't work properly. >>> >>> >>> ept identity pagetable and apic access page in kvm are pinned in memory. >>> As a result, they cannot be migrated/hot-removed. >>> >>> But actually they don't need to be pinned in memory. >>> >>> This patch-set introduces two new vcpu requests: KVM_REQ_MIGRATE_EPT and KVM_REQ_MIGRATE_APIC. >>> These two requests are made when the two pages are migrated by the mmu_notifier >>> to reset the related variable to unusable value. And will also be made when >>> ept violation happens to reset new pages. >>> >>> >>> [Known problem] >>> After this patch-set applied, the two pages can be migrated/hot-removed. >>> But after migrating apic access page, the guest died. >>> >>> The host physical address of apic access page is stored in VMCS. I reset >>> it to 0 to stop guest from accessing it when it is unmapped by >>> kvm_mmu_notifier_invalidate_page(). And reset it to new page's host physical >>> address in tdp_page_fault(). But it seems that guest will access apic page >>> directly by the host physical address. >> >> Would you please to give some advice about this problem ? >> > I haven't reviewed third patch yet, will do ASAP. > I printed some info in the kernel, and I found that mmu_notifier unmapped the apic page and set VMCS APIC_ACCESS_ADDR to 0. But apic page ept violation didn't happen. And the guest stopped running. I think when guest tried to access apic page, there was no ept violation happened. And as a result, VMCS APIC_ACCESS_ADDR was not correctly set. Referring to Intel Software Developer's Manuel Vol 3B, when accessing apic page using translation with a large page (2M, 4M, 1G), APIC VM_exit will not happen. How do you think about this ? Thanks. :) -- 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/