From: Gleb Natapov <gleb@redhat.com>
To: kvm@vger.kernel.org
Cc: avi@redhat.com, mtosatti@redhat.com, mst@redhat.com
Subject: [PATCH] kvm_para_available() should check hypervisor bit before accessing hypervisor cpuid leaf.
Date: Mon, 30 Apr 2012 14:45:49 +0300 [thread overview]
Message-ID: <20120430114549.GA22191@redhat.com> (raw)
This couid range does not exist on real HW and Intel spec says that
"Information returned for highest basic information leaf" will be
returned. Not very well defined.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 99c4bbe..a7a7a94 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -178,14 +178,16 @@ static inline int kvm_para_available(void)
unsigned int eax, ebx, ecx, edx;
char signature[13];
- cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
- memcpy(signature + 0, &ebx, 4);
- memcpy(signature + 4, &ecx, 4);
- memcpy(signature + 8, &edx, 4);
- signature[12] = 0;
-
- if (strcmp(signature, "KVMKVMKVM") == 0)
- return 1;
+ if (cpu_has_hypervisor) {
+ cpuid(KVM_CPUID_SIGNATURE, &eax, &ebx, &ecx, &edx);
+ memcpy(signature + 0, &ebx, 4);
+ memcpy(signature + 4, &ecx, 4);
+ memcpy(signature + 8, &edx, 4);
+ signature[12] = 0;
+
+ if (strcmp(signature, "KVMKVMKVM") == 0)
+ return 1;
+ }
return 0;
}
--
Gleb.
next reply other threads:[~2012-04-30 11:45 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-30 11:45 Gleb Natapov [this message]
2012-04-30 16:37 ` [PATCH] kvm_para_available() should check hypervisor bit before accessing hypervisor cpuid leaf Davidlohr Bueso
2012-05-01 6:52 ` Gleb Natapov
2012-05-01 12:50 ` Avi Kivity
2012-05-01 12:55 ` Gleb Natapov
2012-05-01 12:59 ` Avi Kivity
2012-05-02 12:09 ` Gleb Natapov
2012-05-06 12:55 ` Avi Kivity
2012-05-06 13:00 ` Avi Kivity
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