From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Jan Beulich <jbeulich@suse.com>,
Ross Lagerwall <ross.lagerwall@citrix.com>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
"Roger Pau Monné" <roger@xenproject.org>,
"Jason Andryuk" <jason.andryuk@amd.com>,
"Teddy Astie" <teddy.astie@vates.tech>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v1] x86/svm: Intercept CR0 writes selectively
Date: Thu, 3 Sep 2026 15:31:53 +0100 [thread overview]
Message-ID: <1acb3901-c159-49c5-bd59-aa7be58c67cb@citrix.com> (raw)
In-Reply-To: <6ecdf1d1-784e-4cc0-b840-f8970a295ed5@citrix.com>
On 03/09/2026 3:31 pm, Andrew Cooper wrote:
> On 03/09/2026 2:02 pm, Jan Beulich wrote:
>>> Aside from potentially reducing a few
>>> VMEXITs, this fixes a nested virt bug where L1 intercepts CR0_SEL_WRITE
>>> and L0 intercepts CR0_WRITE. The hardware prioritizes CR0_WRITE and so
>>> L1 never sees any CR0 writes.
>> Yet if L1 sets CR0_WRITE, since intercept masks are ORed together (if
>> I'm not mistaken),
> L0's choice of intercepts needs combining with L1's choice of intercepts.
>
> Mostly this is OR-ing/unioning, but not exclusively, just like levelling
> for migrate isn't a straight interception.
Sorry, intersection.
~Andrew
prev parent reply other threads:[~2026-09-03 14:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 14:19 [PATCH v1] x86/svm: Intercept CR0 writes selectively Ross Lagerwall
2026-09-03 13:02 ` Jan Beulich
2026-09-03 13:35 ` Ross Lagerwall
2026-09-03 13:48 ` Jan Beulich
2026-09-03 14:31 ` Andrew Cooper
2026-09-03 14:31 ` Andrew Cooper [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=1acb3901-c159-49c5-bd59-aa7be58c67cb@citrix.com \
--to=andrew.cooper3@citrix.com \
--cc=jason.andryuk@amd.com \
--cc=jbeulich@suse.com \
--cc=roger@xenproject.org \
--cc=ross.lagerwall@citrix.com \
--cc=teddy.astie@vates.tech \
--cc=xen-devel@lists.xenproject.org \
/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.