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Subject[PATCH 164/208] x86/fpu, crypto x86/serpent_avx2: Simplify the init() xfeature checks
Date
Use the new 'cpu_has_xfeatures()' function to query AVX CPU support.

This has the following advantages to the driver:

- Decouples the driver from FPU internals: it's now only using <asm/fpu/api.h>.

- Removes detection complexity from the driver, no more raw XGETBV instruction

- Shrinks the code a bit.

- Standardizes feature name error message printouts across drivers

There are also advantages to the x86 FPU code: once all drivers
are decoupled from internals we can move them out of common
headers and we'll also be able to remove xcr.h.

Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/crypto/serpent_avx2_glue.c | 15 ++++-----------
1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/arch/x86/crypto/serpent_avx2_glue.c b/arch/x86/crypto/serpent_avx2_glue.c
index aa325fa5c7a6..f226ad41fde1 100644
--- a/arch/x86/crypto/serpent_avx2_glue.c
+++ b/arch/x86/crypto/serpent_avx2_glue.c
@@ -20,8 +20,7 @@
#include <crypto/lrw.h>
#include <crypto/xts.h>
#include <crypto/serpent.h>
-#include <asm/xcr.h>
-#include <asm/fpu/xstate.h>
+#include <asm/fpu/api.h>
#include <asm/crypto/serpent-avx.h>
#include <asm/crypto/glue_helper.h>

@@ -537,16 +536,10 @@ static struct crypto_alg srp_algs[10] = { {

static int __init init(void)
{
- u64 xcr0;
+ const char *feature_name;

- if (!cpu_has_avx2 || !cpu_has_osxsave) {
- pr_info("AVX2 instructions are not detected.\n");
- return -ENODEV;
- }
-
- xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
- if ((xcr0 & (XSTATE_SSE | XSTATE_YMM)) != (XSTATE_SSE | XSTATE_YMM)) {
- pr_info("AVX detected but unusable.\n");
+ if (!cpu_has_xfeatures(XSTATE_SSE | XSTATE_YMM, &feature_name)) {
+ pr_info("CPU feature '%s' is not supported.\n", feature_name);
return -ENODEV;
}

--
2.1.0


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