[PATCH RESEND] raid6: add missing vzeroupper to AVX2 code

[Eric Biggers <ebiggers@kernel.org>]

Since the AVX2 optimized RAID6 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.

Fixes: 2c935842bdb4 ("lib/raid6: Add AVX2 optimized gen_syndrome functions")
Fixes: 7056741fd9fc ("lib/raid6: Add AVX2 optimized recovery functions")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---

This didn't get taken through the x86 tree.  Andrew, it seems you're
taking patches to lib/raid/.  Can you apply this one?

 lib/raid/raid6/x86/avx2.c       | 6 ++++++
 lib/raid/raid6/x86/recov_avx2.c | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/lib/raid/raid6/x86/avx2.c b/lib/raid/raid6/x86/avx2.c
index 7d829c669ea7..3cc2fe7ac42c 100644
--- a/lib/raid/raid6/x86/avx2.c
+++ b/lib/raid/raid6/x86/avx2.c
@@ -67,6 +67,7 @@ static void raid6_avx21_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -115,6 +116,7 @@ static void raid6_avx21_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -175,6 +177,7 @@ static void raid6_avx22_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -243,6 +246,7 @@ static void raid6_avx22_xor_syndrome(int disks, int start, int stop,
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -334,6 +338,7 @@ static void raid6_avx24_gen_syndrome(int disks, size_t bytes, void **ptrs)
 	}
 
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -444,6 +449,7 @@ static void raid6_avx24_xor_syndrome(int disks, int start, int stop,
 		asm volatile("vmovntdq %%ymm14,%0" : "=m" (q[d+96]));
 	}
 	asm volatile("sfence" : : : "memory");
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
diff --git a/lib/raid/raid6/x86/recov_avx2.c b/lib/raid/raid6/x86/recov_avx2.c
index a714a780a2d8..820871046e30 100644
--- a/lib/raid/raid6/x86/recov_avx2.c
+++ b/lib/raid/raid6/x86/recov_avx2.c
@@ -176,6 +176,7 @@ static void raid6_2data_recov_avx2(int disks, size_t bytes, int faila,
 #endif
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 
@@ -293,6 +294,7 @@ static void raid6_datap_recov_avx2(int disks, size_t bytes, int faila,
 #endif
 	}
 
+	asm volatile("vzeroupper");
 	kernel_fpu_end();
 }
 

base-commit: cee9395acd8043be0644b25c34bfa86623f2b935
prerequisite-patch-id: ebf41d9b9e92708245f6ae0657896ff3f8ef7d0d
-- 
2.55.0