linux-kernel - Re: [PATCH 0/3] x86/umip: Fix UMIP insn decoder false positives

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Message-ID: <20250919144652.GDaM1s3CVU5KMMFGkv@fat_crate.local>
Date: Fri, 19 Sep 2025 16:46:52 +0200
From: Borislav Petkov <bp@...en8.de>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, Dan Snyder <dansnyder@...gle.com>
Subject: Re: [PATCH 0/3] x86/umip: Fix UMIP insn decoder false positives

On Fri, Sep 19, 2025 at 07:31:16AM -0700, Sean Christopherson wrote:
> On Fri, Aug 08, 2025, Sean Christopherson wrote:
> > Fix two false positives scenarios where the UMIP #GP logic will incorrectly
> > trigger emulation, e.g. due to a partially decoded instruction, or on
> > instructions like VMLAUNCH that usurp the register form of '0f 01'.
> > 
> > Tested with the hack-a-test patch at the end, but I haven't done any testing
> > using a real userspace (neither positive nor negative testing).
> > 
> > Sean Christopherson (3):
> >   x86/umip: Check that the instruction opcode is at least two bytes
> >   x86/umip: Fix decoding of register forms of 0F 01 (SGDT and SIDT
> >     aliases)
> 
> Ping on these two, looks like they slipped through the cracks.  FWIW, I wouldn't
> consider these urgent enough to squeeze into 6.17, but it'd be nice to get them
> into 6.18.

Lemme take a look...

-- 
Regards/Gruss,
    Boris.

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