[PATCH 6.1] xor: add missing vzeroupper to AVX code

[PATCH 6.1] xor: add missing vzeroupper to AVX code

[Eric Biggers]

commit 7b8fc26c40d6cf4c6751a045c9e42bbb7e78d81b upstream.

Since the AVX optimized XOR code uses YMM registers, execute vzeroupper
before returning from it.  This is needed to avoid degrading the
performance of any later SSE code that may happen to be executed.

(Backported to the old organization of the XOR code.)

Link: https://lore.kernel.org/20260831212248.213805-1-ebiggers@kernel.org
Fixes: ea4d26ae24e5 ("raid5: add AVX optimized RAID5 checksumming")
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: <stable@vger.kernel.org>
---
 arch/x86/include/asm/xor_avx.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/xor_avx.h b/arch/x86/include/asm/xor_avx.h
index 7f81dd5897f41..c6450acd055d1 100644
--- a/arch/x86/include/asm/xor_avx.h
+++ b/arch/x86/include/asm/xor_avx.h
@@ -50,6 +50,7 @@ do { \
 		p1 = (unsigned long *)((uintptr_t)p1 + 512);
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -81,6 +82,7 @@ do { \
 		p2 = (unsigned long *)((uintptr_t)p2 + 512);
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -116,6 +118,7 @@ do { \
 		p3 = (unsigned long *)((uintptr_t)p3 + 512);
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -155,6 +158,7 @@ do { \
 		p4 = (unsigned long *)((uintptr_t)p4 + 512);
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 

base-commit: c75b0cf0982c00cddfd88d1acf3872f79b40980c
-- 
2.56.0