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x86/fpu/xstate: Remove xstate offset check

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Traditionally, new xstate components have been assigned sequentially,
aligning feature numbers with their offsets in the XSAVE buffer. However,
this ordering is not architecturally mandated in the non-compacted
format, where a component's offset may not correspond to its feature
number.

The kernel caches CPUID-reported xstate component details, including size
and offset in the non-compacted format. As part of this process, a sanity
check is also conducted to ensure alignment between feature numbers and
offsets.

This check was likely intended as a general guideline rather than a
strict requirement. Upcoming changes will support out-of-order offsets.
Remove the check as becoming obsolete.

Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250320234301.8342-2-chang.seok.bae@intel.com
This commit is contained in:
Chang S. Bae 2025-03-20 16:42:52 -07:00 committed by Ingo Molnar
parent 8ffd015db8
commit 031b33ef1a
1 changed files with 0 additions and 13 deletions
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13
arch/x86/kernel/fpu/xstate.c
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@ -216,9 +216,6 @@ static bool xfeature_enabled(enum xfeature xfeature)
static void __init setup_xstate_cache(void)
{
u32 eax, ebx, ecx, edx, i;
/* start at the beginning of the "extended state" */
unsigned int last_good_offset = offsetof(struct xregs_state,
extended_state_area);
/*
* The FP xstates and SSE xstates are legacy states. They are always
* in the fixed offsets in the xsave area in either compacted form
@ -246,16 +243,6 @@ static void __init setup_xstate_cache(void)
continue;
xstate_offsets[i] = ebx;
/*
* In our xstate size checks, we assume that the highest-numbered
* xstate feature has the highest offset in the buffer. Ensure
* it does.
*/
WARN_ONCE(last_good_offset > xstate_offsets[i],
"x86/fpu: misordered xstate at %d\n", last_good_offset);
last_good_offset = xstate_offsets[i];
}
}