From: Sean Christopherson <seanjc@google.com>
To: Yan Zhao <yan.y.zhao@intel.com>
Cc: pbonzini@redhat.com, rick.p.edgecombe@intel.com,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH 2/4] KVM: x86/tdp_mmu: Merge the prefetch into the is_access_allowed() check
Date: Fri, 7 Feb 2025 07:03:46 -0800 [thread overview]
Message-ID: <Z6Yg0pORbMyC-9xA@google.com> (raw)
In-Reply-To: <20250207030810.1701-1-yan.y.zhao@intel.com>
On Fri, Feb 07, 2025, Yan Zhao wrote:
> Merge the prefetch check into the is_access_allowed() check to determine a
> spurious fault.
>
> In the TDP MMU, a spurious prefetch fault should also pass the
> is_access_allowed() check.
How so?
1. vCPU takes a write-fault on a swapped out page and queues an async #PF
2. A different task installs a writable SPTE
3. A third task write-protects the SPTE for dirty logging
4. Async #PF handler faults in the SPTE, encounters a read-only SPTE for its
write fault.
KVM shouldn't mark the gfn as dirty in this case.
next prev parent reply other threads:[~2025-02-07 15:03 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-07 3:06 [PATCH 0/4] Small changes related to prefetch and spurious faults Yan Zhao
2025-02-07 3:07 ` [PATCH 1/4] KVM: x86/mmu: Further check old SPTE is leaf for spurious prefetch fault Yan Zhao
2025-02-07 3:08 ` [PATCH 2/4] KVM: x86/tdp_mmu: Merge the prefetch into the is_access_allowed() check Yan Zhao
2025-02-07 15:03 ` Sean Christopherson [this message]
2025-02-08 2:29 ` Yan Zhao
2025-02-10 22:17 ` Sean Christopherson
2025-02-07 3:09 ` [PATCH 3/4] KVM: x86/mmu: Make sure pfn is not changed for spurious fault Yan Zhao
2025-02-07 15:07 ` Sean Christopherson
2025-02-08 2:37 ` Yan Zhao
2025-02-10 22:23 ` Sean Christopherson
2025-02-11 6:48 ` Yan Zhao
2025-02-07 3:09 ` [PATCH 4/4] KVM: x86/mmu: Free obsolete roots when pre-faulting SPTEs Yan Zhao
2025-02-07 15:12 ` Sean Christopherson
2025-02-08 3:01 ` Yan Zhao
2025-02-10 22:41 ` Sean Christopherson
2025-02-11 5:38 ` Yan Zhao
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=Z6Yg0pORbMyC-9xA@google.com \
--to=seanjc@google.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.com \
--cc=rick.p.edgecombe@intel.com \
--cc=yan.y.zhao@intel.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.