[PATCH v2 03/26] KVM: x86 emulator: change ->get_cpuid() accessor to use the x86 semantics

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Instead of getting an exact leaf, follow the spec and fall back to the last
main leaf instead.  This lets us easily emulate the cpuid instruction in the
emulator.

Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
 arch/x86/include/asm/kvm_emulate.h |  4 +--
 arch/x86/kvm/emulate.c             | 53 +++++++++++++++++++-------------------
 arch/x86/kvm/x86.c                 | 20 ++------------
 3 files changed, 30 insertions(+), 47 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 1ac46c22..cd5c96b 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -192,8 +192,8 @@ struct x86_emulate_ops {
 			 struct x86_instruction_info *info,
 			 enum x86_intercept_stage stage);
 
-	bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt,
-			 u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
+	void (*get_cpuid)(struct x86_emulate_ctxt *ctxt,
+			  u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
 };
 
 typedef u32 __attribute__((vector_size(16))) sse128_t;
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index f95d242..ba1f8ec 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1993,8 +1993,8 @@ static bool vendor_intel(struct x86_emulate_ctxt *ctxt)
 	u32 eax, ebx, ecx, edx;
 
 	eax = ecx = 0;
-	return ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx)
-		&& ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx
+	ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
+	return ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx
 		&& ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx
 		&& edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx;
 }
@@ -2013,32 +2013,31 @@ static bool em_syscall_is_enabled(struct x86_emulate_ctxt *ctxt)
 
 	eax = 0x00000000;
 	ecx = 0x00000000;
-	if (ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx)) {
-		/*
-		 * Intel ("GenuineIntel")
-		 * remark: Intel CPUs only support "syscall" in 64bit
-		 * longmode. Also an 64bit guest with a
-		 * 32bit compat-app running will #UD !! While this
-		 * behaviour can be fixed (by emulating) into AMD
-		 * response - CPUs of AMD can't behave like Intel.
-		 */
-		if (ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx &&
-		    ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx &&
-		    edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx)
-			return false;
+	ops->get_cpuid(ctxt, &eax, &ebx, &ecx, &edx);
+	/*
+	 * Intel ("GenuineIntel")
+	 * remark: Intel CPUs only support "syscall" in 64bit
+	 * longmode. Also an 64bit guest with a
+	 * 32bit compat-app running will #UD !! While this
+	 * behaviour can be fixed (by emulating) into AMD
+	 * response - CPUs of AMD can't behave like Intel.
+	 */
+	if (ebx == X86EMUL_CPUID_VENDOR_GenuineIntel_ebx &&
+	    ecx == X86EMUL_CPUID_VENDOR_GenuineIntel_ecx &&
+	    edx == X86EMUL_CPUID_VENDOR_GenuineIntel_edx)
+		return false;
 
-		/* AMD ("AuthenticAMD") */
-		if (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx &&
-		    ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx &&
-		    edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx)
-			return true;
-
-		/* AMD ("AMDisbetter!") */
-		if (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx &&
-		    ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx &&
-		    edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx)
-			return true;
-	}
+	/* AMD ("AuthenticAMD") */
+	if (ebx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ebx &&
+	    ecx == X86EMUL_CPUID_VENDOR_AuthenticAMD_ecx &&
+	    edx == X86EMUL_CPUID_VENDOR_AuthenticAMD_edx)
+		return true;
+
+	/* AMD ("AMDisbetter!") */
+	if (ebx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ebx &&
+	    ecx == X86EMUL_CPUID_VENDOR_AMDisbetterI_ecx &&
+	    edx == X86EMUL_CPUID_VENDOR_AMDisbetterI_edx)
+		return true;
 
 	/* default: (not Intel, not AMD), apply Intel's stricter rules... */
 	return false;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 6ed5983..0d3adaf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4297,26 +4297,10 @@ static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
 	return kvm_x86_ops->check_intercept(emul_to_vcpu(ctxt), info, stage);
 }
 
-static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
+static void emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
 			       u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
 {
-	struct kvm_cpuid_entry2 *cpuid = NULL;
-
-	if (eax && ecx)
-		cpuid = kvm_find_cpuid_entry(emul_to_vcpu(ctxt),
-					    *eax, *ecx);
-
-	if (cpuid) {
-		*eax = cpuid->eax;
-		*ecx = cpuid->ecx;
-		if (ebx)
-			*ebx = cpuid->ebx;
-		if (edx)
-			*edx = cpuid->edx;
-		return true;
-	}
-
-	return false;
+	kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx);
 }
 
 static struct x86_emulate_ops emulate_ops = {
-- 
1.7.11

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