[Qemu-devel] [PATCH] i386: derive '-cpu host' from KVM_GET_SUPPORTED_CPUID

[Avi Kivity]

The fact that a host cpu supports a feature doesn't mean that QEMU and KVM
will also support it, yet -cpuid host brings host features wholesale.

We need to whitelist each feature separately to make sure we support it.
This patch adds KVM whitelisting (by simply using KVM_GET_SUPPORTED_CPUID
instead of the CPUID instruction).

Signed-off-by: Avi Kivity <address@hidden>
---
 target-i386/cpuid.c |   27 ++++-----------------------
 1 files changed, 4 insertions(+), 23 deletions(-)

diff --git a/target-i386/cpuid.c b/target-i386/cpuid.c
index 1e8bcff..edac377 100644
--- a/target-i386/cpuid.c
+++ b/target-i386/cpuid.c
@@ -107,33 +107,14 @@ void host_cpuid(uint32_t function, uint32_t count,
                 uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)
 {
 #if defined(CONFIG_KVM)
-    uint32_t vec[4];
-
-#ifdef __x86_64__
-    asm volatile("cpuid"
-                 : "=a"(vec[0]), "=b"(vec[1]),
-                   "=c"(vec[2]), "=d"(vec[3])
-                 : "0"(function), "c"(count) : "cc");
-#else
-    asm volatile("pusha \n\t"
-                 "cpuid \n\t"
-                 "mov %%eax, 0(%2) \n\t"
-                 "mov %%ebx, 4(%2) \n\t"
-                 "mov %%ecx, 8(%2) \n\t"
-                 "mov %%edx, 12(%2) \n\t"
-                 "popa"
-                 : : "a"(function), "c"(count), "S"(vec)
-                 : "memory", "cc");
-#endif
-
     if (eax)
-        *eax = vec[0];
+        *eax = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EAX);
     if (ebx)
-        *ebx = vec[1];
+        *ebx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EBX);
     if (ecx)
-        *ecx = vec[2];
+        *ecx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_ECX);
     if (edx)
-        *edx = vec[3];
+        *edx = kvm_arch_get_supported_cpuid(kvm_state, function, count, R_EDX);
 #endif
 }
 
-- 
1.7.7.1