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From: "Ronan Pigott" <ronan@rjp.ie>
To: "Borislav Petkov" <bp@alien8.de>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: Re: UMIP and clearcpuid=
Date: Wed, 10 Jun 2026 20:41:02 +0000	[thread overview]
Message-ID: <3868008f140c843f4443b79d800dba5456df174a@rjp.ie> (raw)
In-Reply-To: <20260610200054.GDainCdpF585khK77w@fat_crate.local>

Hi Boris,

June 10, 2026 at 1:00 PM, "Borislav Petkov" <bp@alien8.de> wrote:

> The reason for wanting to disable it being?

My use case is playing Windows video games via Wine. For whatever reason,
they like to use these instructions:

  $ journalctl -b -g umip -o cat --since=-5m
  umip_printk: 117 callbacks suppressed
  umip: StreetFighter6.[3837] ip:15f523f4d sp:524fecb0: SGDT instruction cannot be used by applications.
  umip: StreetFighter6.[3837] ip:15f523f4d sp:524fecb0: For now, expensive software emulation returns the result.
  umip: StreetFighter6.[3837] ip:15f523f4d sp:524fec20: SGDT instruction cannot be used by applications.
  umip: StreetFighter6.[3837] ip:15f523f4d sp:524fec20: For now, expensive software emulation returns the result.
  umip: StreetFighter6.[3837] ip:15f523f4d sp:524fecb0: SGDT instruction cannot be used by applications.

I don't think I benefit from the UMIP protection or the emulation, so I'd
rather just disable it. clearcpuid still works, but results in a tainted
kernel etc:

  kernel: clearcpuid: force-disabling CPU feature flag: umip
  kernel: !!! setcpuid=/clearcpuid= in use, this is for TESTING ONLY, may break things horribly. Tainting kernel.

so I think a umip=no flag as originally proposed could be preferable. Would
that be acceptable?

Cheers,

Ronan

  reply	other threads:[~2026-06-10 20:41 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-10 19:46 Ronan Pigott
2026-06-10 20:00 ` Borislav Petkov
2026-06-10 20:41   ` Ronan Pigott [this message]
2026-06-10 23:55     ` Borislav Petkov
2026-06-11  7:53       ` Peter Zijlstra
2026-06-11 16:09         ` Borislav Petkov
2026-06-11 18:37           ` Peter Zijlstra
2026-06-12  2:21             ` Borislav Petkov
2026-06-12  6:42               ` Peter Zijlstra
2026-06-12 14:49                 ` Borislav Petkov
2026-08-14 11:50             ` Peter Zijlstra
2026-08-14 12:12               ` Peter Zijlstra
2026-08-14 12:57                 ` Andrew Cooper
2026-08-14 13:23                   ` Peter Zijlstra
2026-08-17 21:39                     ` Kenny Wottrich
2026-08-14 12:19             ` Peter Zijlstra

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