include/qemu/cpuid: Introduce xgetbv_low

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comment about "older versions of the assember" is obsolete, as even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>

diff --git a/include/qemu/cpuid.h b/include/qemu/cpuid.h
index 7adb12d32028d89818c49850f08982ccd39d7250..1451e8ef2fe7f38fac9fc13dc82ee4eb92f9190a 100644 (file)
--- a/include/qemu/cpuid.h
+++ b/include/qemu/cpuid.h
@@ -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 */

diff --git a/tcg/i386/tcg-target.c.inc b/tcg/i386/tcg-target.c.inc
index 883ced8168335f84a4edb315f67bb1edad68988e..028ece62a04fe7f6812b1ece82d2a46566988602 100644 (file)
--- a/tcg/i386/tcg-target.c.inc
+++ b/tcg/i386/tcg-target.c.inc
@@ -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;

diff --git a/util/bufferiszero.c b/util/bufferiszero.c
index 1790ded7d42c498f6ec576310c8af6fa7bceb443..1886bc5ba438a7b363def1879ab479e6f74524ed 100644 (file)
--- a/util/bufferiszero.c
+++ b/util/bufferiszero.c
@@ -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;