From: Sean Christopherson <seanjc@google.com>
To: Mingwei Zhang <mizhang@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm <kvm@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
Ben Gardon <bgardon@google.com>,
David Matlack <dmatlack@google.com>
Subject: Re: [PATCH] KVM: x86/mmu: add lockdep check before lookup_address_in_mm()
Date: Wed, 27 Apr 2022 01:16:33 +0000 [thread overview]
Message-ID: <YmiZcZf9YXxMVcfx@google.com> (raw)
In-Reply-To: <CAL715WK8-cOJWK+iai=ygdOTzPb-QUvEwa607tVEkmGOu3gyQA@mail.gmail.com>
On Tue, Apr 26, 2022, Mingwei Zhang wrote:
> > I completely agree that lookup_address() and friends are unnecessarily fragile,
> > but I think that attempting to harden them to fix this KVM bug will open a can
> > of worms and end up delaying getting KVM fixed.
>
> So basically, we need to:
> - choose perf_get_page_size() instead of using any of the
> lookup_address*() in mm.
> - add a wrapper layer to adapt: 1) irq disabling/enabling and 2) size
> -> level translation.
>
> Agree?
Drat, I didn't see that it returns the page size, not the level. That's a bit
unfortunate. It definitely makes me less averse to fixing lookup_address_in_pgd()
Hrm. I guess since we know there's at least one broken user, and in theory
fixing lookup_address_in_pgd() should do no harm to users that don't need protection,
it makes sense to just fix lookup_address_in_pgd() and see if the x86 maintainers
push back.
next prev parent reply other threads:[~2022-04-27 1:16 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-27 20:58 [PATCH] KVM: x86/mmu: add lockdep check before lookup_address_in_mm() Mingwei Zhang
2022-03-28 15:16 ` Sean Christopherson
2022-03-28 17:41 ` Mingwei Zhang
2022-03-28 18:15 ` Sean Christopherson
2022-04-26 17:19 ` Mingwei Zhang
2022-04-26 17:49 ` Paolo Bonzini
2022-04-26 18:10 ` Sean Christopherson
2022-04-26 18:48 ` Mingwei Zhang
2022-04-27 1:16 ` Sean Christopherson [this message]
2022-04-27 1:24 ` Mingwei Zhang
2022-04-27 1:30 ` Sean Christopherson
2022-04-27 2:56 ` Mingwei Zhang
2022-04-27 14:08 ` Sean Christopherson
-- strict thread matches above, loose matches on Subject: below --
2022-03-27 20:35 Mingwei Zhang
2022-03-27 20:43 ` Mingwei Zhang
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=YmiZcZf9YXxMVcfx@google.com \
--to=seanjc@google.com \
--cc=bgardon@google.com \
--cc=dmatlack@google.com \
--cc=jmattson@google.com \
--cc=joro@8bytes.org \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mizhang@google.com \
--cc=pbonzini@redhat.com \
--cc=vkuznets@redhat.com \
--cc=wanpengli@tencent.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