From: Ross Lagerwall <ross.lagerwall@citrix.com>
To: Jan Beulich <jbeulich@suse.com>
Cc: "Paul Durrant" <paul@xen.org>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Roger Pau Monné" <roger@xenproject.org>,
"Teddy Astie" <teddy.astie@vates.tech>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH v1 1/2] x86/viridian: Workaround Hyper-V GP fault writing to MSR
Date: Thu, 3 Sep 2026 11:55:48 +0100 [thread overview]
Message-ID: <12a277aa-2d67-436a-8afa-3a68ad6f6ae1@citrix.com> (raw)
In-Reply-To: <39ccc2f5-7b3e-4c5f-a98c-b526f12bb1c7@suse.com>
On 9/3/26 11:44 AM, Jan Beulich wrote:
> On 28.08.2026 15:11, Ross Lagerwall wrote:
>> The Viridian spec requires the vector to be >= 0x10 when writing to the
>> SINTx MSR, otherwise it should #GP fault.
>> The spec-defined initial value is 0x0000000000010000, i.e. the vector is
>> 0. On startup, for some reason Windows 11 Hyper-V tries to set the MSR to
>> the spec-defined initial value and since the vector is 0, it GP faults.
>> To workaround this, treat the write as a no-op if the value is
>> unchanged.
>>
>> Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
>
> Acked-by: Jan Beulich <jbeulich@suse.com>
>
> I expect that despite the (valid) absence of a Fixes: tag this will want
> backporting.
It should be fine to backport, though in general I think backporting nested
virt fixes at this point is not needed as there will be too many changes to go
into the stable releases for it to reach a usable state.
Ross
next prev parent reply other threads:[~2026-09-03 10:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-28 13:11 [PATCH v1 0/2] Viridian changes for Hyper-V as a guest Ross Lagerwall
2026-08-28 13:11 ` [PATCH v1 1/2] x86/viridian: Workaround Hyper-V GP fault writing to MSR Ross Lagerwall
2026-09-03 10:44 ` Jan Beulich
2026-09-03 10:55 ` Ross Lagerwall [this message]
2026-09-03 11:14 ` Jan Beulich
2026-09-03 11:26 ` Ross Lagerwall
2026-09-03 10:50 ` Andrew Cooper
2026-08-28 13:11 ` [PATCH v1 2/2] x86/viridian: Implement synthetic timer direct mode Ross Lagerwall
2026-08-28 14:11 ` Tu Dinh
2026-08-28 14:17 ` Ross Lagerwall
2026-09-03 11:12 ` Jan Beulich
2026-09-04 12:40 ` Ross Lagerwall
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=12a277aa-2d67-436a-8afa-3a68ad6f6ae1@citrix.com \
--to=ross.lagerwall@citrix.com \
--cc=andrew.cooper3@citrix.com \
--cc=jbeulich@suse.com \
--cc=paul@xen.org \
--cc=roger@xenproject.org \
--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.