[PATCH RFC v2 1/9] x86/fpu/xstate: Remove xstate offset check

[Chang S. Bae]

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@xxxxxxxxx>
---
 arch/x86/kernel/fpu/xstate.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 6a41d1610d8b..542c6981180d 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -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];
 	}
 }
 
-- 
2.45.2