linux-kernel - Re: [PATCH] x86/CPU/AMD: Ignore invalid reset reason value

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20250722165615.GCaH_CryG7kNrAS4O6@renoirsky.local>
Date: Tue, 22 Jul 2025 18:56:15 +0200
From: Borislav Petkov <bp@...en8.de>
To: Yazen Ghannam <yazen.ghannam@....com>
Cc: x86@...nel.org, linux-kernel@...r.kernel.org,
	Libing He <libhe@...hat.com>, David Arcari <darcari@...hat.com>,
	Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH] x86/CPU/AMD: Ignore invalid reset reason value

On Mon, Jul 21, 2025 at 06:11:54PM +0000, Yazen Ghannam wrote:
> The reset reason value may be "all bits set", e.g. 0xFFFFFFFF. This is a
> commonly used error response from hardware. This may occur due to a real
> hardware issue or when running in a VM.

Well, which is it Libing is reporting? VM or a real hw issue?

If it is a VM, is that -1 the only thing a VMM returns when reading that
MMIO address or can it be anything?

If latter, you need to check X86_FEATURE_HYPERVISOR.

Same for a real hw issue.

IOW, is -1 the *only* invalid data we can read here or are we playing
whack-a-mole with it?

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette