target/i386: add AVX_EN hflag

Add a new hflag bit to determine whether AVX instructions are allowed

Signed-off-by: Paul Brook <paul@nowt.org>
Message-Id: <20220424220204.2493824-4-paul@nowt.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

target/i386/cpu.h

@@ -169,6 +169,7 @@ typedef enum X86Seg {
 #define HF_MPX_EN_SHIFT     25 /* MPX Enabled (CR4+XCR0+BNDCFGx) */
 #define HF_MPX_IU_SHIFT     26 /* BND registers in-use */
 #define HF_UMIP_SHIFT       27 /* CR4.UMIP */
+#define HF_AVX_EN_SHIFT     28 /* AVX Enabled (CR4+XCR0) */
 
 #define HF_CPL_MASK          (3 << HF_CPL_SHIFT)
 #define HF_INHIBIT_IRQ_MASK  (1 << HF_INHIBIT_IRQ_SHIFT)
@@ -195,6 +196,7 @@ typedef enum X86Seg {
 #define HF_MPX_EN_MASK       (1 << HF_MPX_EN_SHIFT)
 #define HF_MPX_IU_MASK       (1 << HF_MPX_IU_SHIFT)
 #define HF_UMIP_MASK         (1 << HF_UMIP_SHIFT)
+#define HF_AVX_EN_MASK       (1 << HF_AVX_EN_SHIFT)
 
 /* hflags2 */
 
@@ -2126,6 +2128,7 @@ void host_cpuid(uint32_t function, uint32_t count,
 
 /* helper.c */
 void x86_cpu_set_a20(X86CPU *cpu, int a20_state);
+void cpu_sync_avx_hflag(CPUX86State *env);
 
 #ifndef CONFIG_USER_ONLY
 static inline int x86_asidx_from_attrs(CPUState *cs, MemTxAttrs attrs)

target/i386/helper.c

@@ -29,6 +29,17 @@
 #endif
 #include "qemu/log.h"
 
+void cpu_sync_avx_hflag(CPUX86State *env)
+{
+    if ((env->cr[4] & CR4_OSXSAVE_MASK)
+        && (env->xcr0 & (XSTATE_SSE_MASK | XSTATE_YMM_MASK))
+            == (XSTATE_SSE_MASK | XSTATE_YMM_MASK)) {
+        env->hflags |= HF_AVX_EN_MASK;
+    } else{
+        env->hflags &= ~HF_AVX_EN_MASK;
+    }
+}
+
 void cpu_sync_bndcs_hflags(CPUX86State *env)
 {
     uint32_t hflags = env->hflags;
@@ -209,6 +220,7 @@ void cpu_x86_update_cr4(CPUX86State *env, uint32_t new_cr4)
     env->hflags = hflags;
 
     cpu_sync_bndcs_hflags(env);
+    cpu_sync_avx_hflag(env);
 }
 
 #if !defined(CONFIG_USER_ONLY)

target/i386/tcg/fpu_helper.c

@@ -2955,6 +2955,7 @@ void helper_xsetbv(CPUX86State *env, uint32_t ecx, uint64_t mask)
 
     env->xcr0 = mask;
     cpu_sync_bndcs_hflags(env);
+    cpu_sync_avx_hflag(env);
     return;
 
  do_gpf: