From: Borislav Petkov <bp@alien8.de>
To: Jason Andryuk <jason.andryuk@amd.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
Mario Limonciello <mario.limonciello@amd.com>,
Yazen Ghannam <yazen.ghannam@amd.com>,
Thomas Gleixner <tglx@kernel.org>, Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Penny Zheng <penny.zheng@amd.com>,
stable@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Avoid divide by 0 in amd_smn_init()
Date: Wed, 24 Jun 2026 10:15:36 -0700 [thread overview]
Message-ID: <20260624171536.GDajwQuLD9pkLRLpLE@fat_crate.local> (raw)
In-Reply-To: <0500111d-91bf-4105-8de3-af44a113157a@amd.com>
On Wed, Jun 24, 2026 at 12:41:48PM -0400, Jason Andryuk wrote:
> I think this is the issue:
>
> The "root" device search was introduced to support SMN access for Zen
> systems. This device represents a PCIe root complex. It is not the
> same as the "CPU/node" devices found at slots 0x18-0x1F.
What is that? AI output?
> We don't want dom0 to access the "CPU/node" devices. It's the "root" device
> SMN access I am trying to retain.
I know what you're trying to do - you want to use SMN accesses on dom0. And
I'm trying to figure out a stable detection method on Xen which is future
proof.
> Many amd_smn_read/write calls have hardcoded node 0, like for amd-pmc.
Maybe.
Whatever it is, it needs to be a long-term solution and properly vetted by Xen
folks so that we don't do crazy hacks for Xen's sake everytime.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2026-06-24 17:16 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-23 21:19 Jason Andryuk
2026-06-23 21:35 ` Borislav Petkov
2026-06-24 15:41 ` Jason Andryuk
2026-06-24 15:59 ` Borislav Petkov
2026-06-24 16:41 ` Jason Andryuk
2026-06-24 17:15 ` Borislav Petkov [this message]
2026-06-24 19:08 ` Jason Andryuk
2026-06-24 19:25 ` Borislav Petkov
2026-06-24 9:21 ` Ingo Molnar
2026-06-24 14:54 ` Borislav Petkov
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=20260624171536.GDajwQuLD9pkLRLpLE@fat_crate.local \
--to=bp@alien8.de \
--cc=andrew.cooper3@citrix.com \
--cc=dave.hansen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=jason.andryuk@amd.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mario.limonciello@amd.com \
--cc=mingo@redhat.com \
--cc=penny.zheng@amd.com \
--cc=stable@vger.kernel.org \
--cc=tglx@kernel.org \
--cc=x86@kernel.org \
--cc=yazen.ghannam@amd.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
all inboxes | Powered by JetHome®