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From: "Ronan Pigott" <ronan@rjp.ie>
To: linux-kernel@vger.kernel.org
Cc: bp@alien8.de, x86@kernel.org
Subject: UMIP and clearcpuid=
Date: Wed, 10 Jun 2026 19:46:11 +0000	[thread overview]
Message-ID: <e60f6e46b74131ebaf54793be00618cf13727ede@rjp.ie> (raw)

Hi,

In [1] the clearcpuid= flag was hidden, but afaik this remains the only way to
disable UMIP. At the time UMIP was enabled, clearcpuid was apparently
determined to be the appropriate method of disablement in [2], and it remains
recommended by the documentation in [3].

If clearcpuid is no good, can we have a sanctioned method to disable UMIP
protections instead then?

[1] https://patch.msgid.link/20260520202508.160112-1-bp@kernel.org

[2] https://lore.kernel.org/lkml/1478760361.2551.21.camel@ranerica-desktop/

[3] https://docs.kernel.org/arch/x86/cpuinfo.html#the-feature-is-disabled-at-boot-time

Cheers,

Ronan

             reply	other threads:[~2026-06-10 19:46 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-06-10 19:46 Ronan Pigott [this message]
2026-06-10 20:00 ` Borislav Petkov
2026-06-10 20:41   ` Ronan Pigott
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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