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include/qemu/cpuid: Introduce xgetbv_low

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Replace the two uses of asm to expand xgetbv with an inline function.
Since one of the two has been using the mnemonic, assume that the
comment about "older versions of the assember" is obsolete, as even
that is 4 years old.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2022-10-25 18:40:48 +10:00
parent 417aeaff54
commit 5d133dd839
3 changed files with 12 additions and 9 deletions
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7
include/qemu/cpuid.h
View File

@ -71,4 +71,11 @@
#define bit_LZCNT (1 << 5)
#endif
static inline unsigned xgetbv_low(unsigned c)
{
unsigned a, d;
asm("xgetbv" : "=a"(a), "=d"(d) : "c"(c));
return a;
}
#endif /* QEMU_CPUID_H */

11
tcg/i386/tcg-target.c.inc
View File

@ -4156,12 +4156,9 @@ static void tcg_target_init(TCGContext *s)
/* There are a number of things we must check before we can be
sure of not hitting invalid opcode. */
if (c & bit_OSXSAVE) {
unsigned xcrl, xcrh;
/* The xgetbv instruction is not available to older versions of
* the assembler, so we encode the instruction manually.
*/
asm(".byte 0x0f, 0x01, 0xd0" : "=a" (xcrl), "=d" (xcrh) : "c" (0));
if ((xcrl & 6) == 6) {
unsigned bv = xgetbv_low(0);
if ((bv & 6) == 6) {
have_avx1 = (c & bit_AVX) != 0;
have_avx2 = (b7 & bit_AVX2) != 0;
@ -4172,7 +4169,7 @@ static void tcg_target_init(TCGContext *s)
* check that OPMASK and all extended ZMM state are enabled
* even if we're not using them -- the insns will fault.
*/
if ((xcrl & 0xe0) == 0xe0
if ((bv & 0xe0) == 0xe0
&& (b7 & bit_AVX512F)
&& (b7 & bit_AVX512VL)) {
have_avx512vl = true;

3
util/bufferiszero.c
View File

@ -258,8 +258,7 @@ static void __attribute__((constructor)) init_cpuid_cache(void)
/* We must check that AVX is not just available, but usable. */
if ((c & bit_OSXSAVE) && (c & bit_AVX) && max >= 7) {
int bv;
__asm("xgetbv" : "=a"(bv), "=d"(d) : "c"(0));
unsigned bv = xgetbv_low(0);
__cpuid_count(7, 0, a, b, c, d);
if ((bv & 0x6) == 0x6 && (b & bit_AVX2)) {
cache |= CACHE_AVX2;