[Qemu-devel] [PATCH v3 uq/master 2/2] x86: cpuid: reconstruct leaf 0Dh data

[Paolo Bonzini <pbonzini@redhat.com>]

The data in leaf 0Dh depends on information from other feature bits.
Instead of passing it blindly from the host, compute it based on
whether these feature bits are enabled.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target-i386/cpu.c | 65 ++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 48 insertions(+), 17 deletions(-)

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index ac83106..1addb18 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -328,6 +328,15 @@ X86RegisterInfo32 x86_reg_info_32[CPU_NB_REGS32] = {
 };
 #undef REGISTER
 
+typedef struct ExtSaveArea {
+    uint32_t feature, bits;
+    uint32_t offset, size;
+} ExtSaveArea;
+
+static const ExtSaveArea ext_save_areas[] = {
+    [2] = { .feature = FEAT_1_ECX, .bits = CPUID_EXT_AVX,
+            .offset = 0x100, .size = 0x240 },
+};
 
 const char *get_register_name_32(unsigned int reg)
 {
@@ -2169,29 +2178,51 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
             *edx = 0;
         }
         break;
-    case 0xD:
+    case 0xD: {
+        KVMState *s = cs->kvm_state;
+        uint64_t kvm_mask;
+        int i;
+
         /* Processor Extended State */
-        if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE)) {
-            *eax = 0;
-            *ebx = 0;
-            *ecx = 0;
-            *edx = 0;
+        *eax = 0;
+        *ebx = 0;
+        *ecx = 0;
+        *edx = 0;
+        if (!(env->features[FEAT_1_ECX] & CPUID_EXT_XSAVE) || !kvm_enabled()) {
             break;
         }
-        if (kvm_enabled()) {
-            KVMState *s = cs->kvm_state;
+        kvm_mask =
+            kvm_arch_get_supported_cpuid(s, 0xd, 0, R_EAX) |
+            ((uint64_t)kvm_arch_get_supported_cpuid(s, 0xd, 0, R_EDX) << 32);
 
-            *eax = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EAX);
-            *ebx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EBX);
-            *ecx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_ECX);
-            *edx = kvm_arch_get_supported_cpuid(s, 0xd, count, R_EDX);
-        } else {
-            *eax = 0;
-            *ebx = 0;
-            *ecx = 0;
-            *edx = 0;
+        if (count == 0) {
+            *ecx = 0x240;
+            for (i = 2; i < ARRAY_SIZE(ext_save_areas); i++) {
+                const ExtSaveArea *esa = &ext_save_areas[i];
+                if ((env->features[esa->feature] & esa->bits) == esa->bits &&
+                    (kvm_mask & (1 << i)) != 0) {
+                    if (i < 32) {
+                        *eax |= 1 << i;
+                    } else {
+                        *edx |= 1 << (i - 32);
+                    }
+                    *ecx = MAX(*ecx, esa->offset + esa->size);
+                }
+            }
+            *eax |= kvm_mask & (XSTATE_FP | XSTATE_SSE);
+            *ebx = *ecx;
+        } else if (count == 1) {
+            *eax = kvm_arch_get_supported_cpuid(s, 0xd, 1, R_EAX);
+        } else if (count < ARRAY_SIZE(ext_save_areas)) {
+            const ExtSaveArea *esa = &ext_save_areas[count];
+            if ((env->features[esa->feature] & esa->bits) == esa->bits &&
+                (kvm_mask & (1 << count)) != 0) {
+                *eax = esa->offset;
+                *ebx = esa->size;
+            }
         }
         break;
+    }
     case 0x80000000:
         *eax = env->cpuid_xlevel;
         *ebx = env->cpuid_vendor1;
-- 
1.8.3.1