From: Sean Christopherson <seanjc@google.com>
To: David Laight <david.laight.linux@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Replace BUG_ON() with WARN_ON_ONCE() on "bad" nested GPA translation
Date: Mon, 22 Jun 2026 16:24:18 -0700 [thread overview]
Message-ID: <ajm6VPapXJNQpkzx@google.com> (raw)
In-Reply-To: <20260619160645.57f4e325@pumpkin>
On Fri, Jun 19, 2026, David Laight wrote:
> On Thu, 18 Jun 2026 11:57:45 -0700
> Sean Christopherson <seanjc@google.com> wrote:
>
> > If KVM attempts to translate what it thinks is an L2 GPA with a non-nested
> > MMU, simply WARN and return the GPA, i.e. trust the MMU more than the
> > caller, as there is zero reason to potentially panic the host kernel just
> > because KVM misused an API.
>
> Except that PANIC_ON_WARN stands a reasonable chance of being set.
Not in cloud environments, or in any environment where the guest workload is
untrusted.
> So it makes little difference.
I disagree, vehemently. There's a massive difference between opting in to
minimizing risk of data corruption at the cost of availability, and forcing all
KVM users to sacrifice availability, especially for no tangible beneft. Paolo
and I are fully aligned on this:
https://lore.kernel.org/all/CABgObfZJV5hU_7WoPWLRH3-EvKts%2BUBZOwtCXmwVZYJP8dDo2A@mail.gmail.com
prev parent reply other threads:[~2026-06-22 23:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-18 18:57 [PATCH] KVM: x86: Replace BUG_ON() with WARN_ON_ONCE() on "bad" nested GPA translation Sean Christopherson
2026-06-19 4:26 ` Huang, Kai
2026-06-19 15:06 ` David Laight
2026-06-22 23:24 ` Sean Christopherson [this message]
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=ajm6VPapXJNQpkzx@google.com \
--to=seanjc@google.com \
--cc=david.laight.linux@gmail.com \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=pbonzini@redhat.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox