From: no-reply@sashiko.virtuozzo.com
To: Konstantin Khorenko <khorenko@virtuozzo.com>,
Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
Vasileios Almpanis <vasileios.almpanis@virtuozzo.com>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v2 4/5] x86/traps: decode the faulting CPUID with the instruction decoder
Date: Tue, 6 Oct 2026 17:25:53 +0000 [thread overview]
Message-ID: <010701a112401bd9-678b62d3-faa4-415a-9077-b8fc3f32dfde-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261006-b4-prep-khorenko-vstor-148656-cpuid-v2-4-f6d1192c7d60@virtuozzo.com>
> check_cpuid_fault() reads two bytes at the faulting ip and emulates
> only when they are 0f a2, the bare CPUID encoding.
>
> CPUID has no operands, so the CPU accepts and ignores every legacy
> and REX prefix in front of it. All of these are valid CPUID and raise
> the same #GP(0) when CPUID faulting is on:
>
> 0f a2 cpuid
> 66 0f a2 data16 cpuid (operand-size override)
> f3 0f a2 repz cpuid
> 2e 0f a2 cs cpuid (segment override)
> 48 0f a2 rex.W cpuid
>
> Only the first one is recognised. For the others the handler reads
> the prefix byte instead of the opcode, declines, and the task is
> [ ... ]
> Fixes: 1033fe455434 ("arch/x86: introduce cpuid override")
> https://virtuozzo.atlassian.net/browse/VSTOR-148843
>
> Feature: x86: cpu pools (cpuid override)
> Signed-off-by: Konstantin Khorenko <khorenko@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261006-b4-prep-khorenko-vstor-148656-cpuid-v2-0-f6d1192c7d60@virtuozzo.com?part=4
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next prev parent reply other threads:[~2026-10-06 17:27 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-06 17:19 [Devel] [PATCH hci-8.1 v2 0/5] x86/ve: CPUID override follow-ups: arm at once, prefixes, selftests Konstantin Khorenko
2026-10-06 17:19 ` [Devel] [PATCH hci-8.1 v2 1/5] selftests/ve: check CPUID override emulation for VE tasks Konstantin Khorenko
2026-10-06 17:29 ` no-reply
2026-10-06 17:19 ` [Devel] [PATCH hci-8.1 v2 2/5] x86/ve: enable CPUID faulting at once when the current task enters a VE Konstantin Khorenko
2026-10-06 17:23 ` no-reply
2026-10-06 17:19 ` [Devel] [PATCH hci-8.1 v2 3/5] selftests/ve: check CPUID override right after entering " Konstantin Khorenko
2026-10-06 17:24 ` no-reply
2026-10-06 17:19 ` [Devel] [PATCH hci-8.1 v2 4/5] x86/traps: decode the faulting CPUID with the instruction decoder Konstantin Khorenko
2026-10-06 17:25 ` no-reply [this message]
2026-10-06 17:19 ` [Devel] [PATCH hci-8.1 v2 5/5] selftests/ve: check CPUID override emulation for a prefixed CPUID Konstantin Khorenko
2026-10-06 17:26 ` no-reply
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