From: Paolo Bonzini <pbonzini@redhat.com>
To: Ben Gardon <bgardon@google.com>
Cc: LKML <linux-kernel@vger.kernel.org>, kvm <kvm@vger.kernel.org>,
Cannon Matthews <cannonmatthews@google.com>,
Peter Xu <peterx@redhat.com>,
Sean Christopherson <sean.j.christopherson@intel.com>,
Peter Shier <pshier@google.com>,
Peter Feiner <pfeiner@google.com>,
Junaid Shahid <junaids@google.com>,
Jim Mattson <jmattson@google.com>,
Yulei Zhang <yulei.kernel@gmail.com>,
Wanpeng Li <kernellwp@gmail.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Xiao Guangrong <xiaoguangrong.eric@gmail.com>
Subject: Re: [PATCH v2 00/20] Introduce the TDP MMU
Date: Tue, 20 Oct 2020 10:07:25 +0200 [thread overview]
Message-ID: <b07db4bf-860c-57cb-6a1d-b5a151c28c9b@redhat.com> (raw)
In-Reply-To: <CANgfPd9CpYt9bVNXWbB+2VTrndfLBezqPauDo2-n8UdKDsrzpA@mail.gmail.com>
On 19/10/20 20:15, Ben Gardon wrote:
> When getting the dirty log, we
> follow the following steps:
> 1. Atomically get and clear an unsigned long of the dirty bitmap
> 2. For each GFN in the range of pages covered by the unsigned long mask:
> 3. Clear the dirty or writable bit on the SPTE
> 4. Copy the mask of dirty pages to be returned to userspace
>
> If we mark the page as dirty in the dirty bitmap in step 3, we'll
> report the page as dirty twice - once in this dirty log call, and
> again in the next one. This can lead to unexpected behavior:
> 1. Pause all vCPUs
> 2. Get the dirty log <--- Returns all pages dirtied before the vCPUs were paused
> 3. Get the dirty log again <--- Unexpectedly returns a non-zero number
> of dirty pages even though no pages were actually dirtied
Got it, that might also fail the dirty_log_test. Thanks!
Paolo
prev parent reply other threads:[~2020-10-20 8:07 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 18:26 [PATCH v2 00/20] Introduce the TDP MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 01/20] kvm: x86/mmu: Separate making SPTEs from set_spte Ben Gardon
2020-10-14 18:26 ` [PATCH v2 02/20] kvm: x86/mmu: Introduce tdp_iter Ben Gardon
2020-10-21 14:58 ` Yu Zhang
2020-10-21 18:08 ` Ben Gardon
2020-10-22 2:34 ` Yu Zhang
2020-10-14 18:26 ` [PATCH v2 03/20] kvm: x86/mmu: Init / Uninit the TDP MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 04/20] kvm: x86/mmu: Allocate and free TDP MMU roots Ben Gardon
2020-10-16 14:56 ` Paolo Bonzini
2020-10-19 17:02 ` Ben Gardon
2020-10-21 15:09 ` Yu Zhang
2020-10-21 17:54 ` Ben Gardon
2020-10-21 18:01 ` Paolo Bonzini
2020-10-14 18:26 ` [PATCH v2 05/20] kvm: x86/mmu: Add functions to handle changed TDP SPTEs Ben Gardon
2020-10-14 18:26 ` [PATCH v2 06/20] KVM: Cache as_id in kvm_memory_slot Ben Gardon
2020-10-14 18:26 ` [PATCH v2 07/20] kvm: x86/mmu: Support zapping SPTEs in the TDP MMU Ben Gardon
2020-10-19 20:49 ` Edgecombe, Rick P
2020-10-19 21:33 ` Ben Gardon
2020-10-21 15:02 ` Yu Zhang
2020-10-21 17:20 ` Paolo Bonzini
2020-10-21 17:24 ` Yu Zhang
2020-10-21 18:00 ` Paolo Bonzini
2020-10-22 2:24 ` Yu Zhang
2020-10-14 18:26 ` [PATCH v2 08/20] kvm: x86/mmu: Separate making non-leaf sptes from link_shadow_page Ben Gardon
2020-10-14 18:26 ` [PATCH v2 09/20] kvm: x86/mmu: Remove disallowed_hugepage_adjust shadow_walk_iterator arg Ben Gardon
2020-10-14 18:26 ` [PATCH v2 10/20] kvm: x86/mmu: Add TDP MMU PF handler Ben Gardon
2020-10-16 15:12 ` Paolo Bonzini
2020-10-14 18:26 ` [PATCH v2 11/20] kvm: x86/mmu: Allocate struct kvm_mmu_pages for all pages in TDP MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 12/20] kvm: x86/mmu: Support invalidate range MMU notifier for " Ben Gardon
2020-10-14 18:26 ` [PATCH v2 13/20] kvm: x86/mmu: Add access tracking for tdp_mmu Ben Gardon
2020-10-14 18:26 ` [PATCH v2 14/20] kvm: x86/mmu: Support changed pte notifier in tdp MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 15/20] kvm: x86/mmu: Support dirty logging for the TDP MMU Ben Gardon
2020-10-16 16:18 ` Paolo Bonzini
2020-10-19 17:07 ` Ben Gardon
2020-10-19 17:42 ` Paolo Bonzini
2020-10-14 18:26 ` [PATCH v2 16/20] kvm: x86/mmu: Support disabling dirty logging for the tdp MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 17/20] kvm: x86/mmu: Support write protection for nesting in " Ben Gardon
2020-10-16 16:18 ` Paolo Bonzini
2020-10-14 18:26 ` [PATCH v2 18/20] kvm: x86/mmu: Support MMIO in the TDP MMU Ben Gardon
2020-10-14 18:26 ` [PATCH v2 19/20] kvm: x86/mmu: Don't clear write flooding count for direct roots Ben Gardon
2020-10-14 18:27 ` [PATCH v2 20/20] kvm: x86/mmu: NX largepage recovery for TDP MMU Ben Gardon
2020-10-16 16:50 ` [PATCH v2 00/20] Introduce the " Paolo Bonzini
2020-10-19 18:15 ` Ben Gardon
2020-10-20 8:07 ` Paolo Bonzini [this message]
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