From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Roger Pau Monne <roger.pau@citrix.com>, <xen-devel@lists.xenproject.org>
Cc: Wei Liu <wl@xen.org>, Jan Beulich <jbeulich@suse.com>
Subject: Re: [Xen-devel] [PATCH] x86/hvm: always expose x2APIC feature in max HVM cpuid policy
Date: Tue, 24 Dec 2019 12:23:12 +0000 [thread overview]
Message-ID: <8264d39f-4f5e-e7c0-f0e0-6be23feba3c3@citrix.com> (raw)
In-Reply-To: <20191224101810.45915-1-roger.pau@citrix.com>
On 24/12/2019 10:18, Roger Pau Monne wrote:
> On hardware without x2APIC support Xen emulated local APIC will
> provide such mode, and hence the feature should be set in the maximum
> HVM cpuid policy.
>
> Not exposing it in the maximum policy results in HVM domains not
> getting such feature exposed unless it's also supported by the
> underlying hardware.
>
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
x2apic has never been exposed via this mechanism, due to its effects on
topology calculations.
It has however always been down to the toolstack to opt in, and Xen
permits this via recalculate_cpuid_policy(), on the expectation that the
toolstack knew what it was doing WRT topology (all evidence actually to
the contrary).
If we're seeing a recent change in behaviour, then it will be from libxc.
~Andrew
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
next prev parent reply other threads:[~2019-12-24 12:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-24 10:18 [Xen-devel] [PATCH] x86/hvm: always expose x2APIC feature in max HVM cpuid policy Roger Pau Monne
2019-12-24 12:23 ` Andrew Cooper [this message]
2019-12-24 12:42 ` Roger Pau Monné
2019-12-24 16:00 ` Andrew Cooper
2019-12-24 18:17 ` Roger Pau Monné
2020-01-09 10:48 ` Roger Pau Monné
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=8264d39f-4f5e-e7c0-f0e0-6be23feba3c3@citrix.com \
--to=andrew.cooper3@citrix.com \
--cc=jbeulich@suse.com \
--cc=roger.pau@citrix.com \
--cc=wl@xen.org \
--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.