[Natty 1/2] KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"

[Stefan Bader]

>From 4daadc97a978d903011c54c2caec5824f06a215d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephan=20B=C3=A4rwolf?= <stephan.baerwolf at tu-ilmenau.de>
Date: Thu, 12 Jan 2012 16:43:03 +0100
Subject: [PATCH 5/6] KVM: x86: extend "struct x86_emulate_ops" with
 "get_cpuid"

In order to be able to proceed checks on CPU-specific properties
within the emulator, function "get_cpuid" is introduced.
With "get_cpuid" it is possible to virtually call the guests
"cpuid"-opcode without changing the VM's context.

[mtosatti: cleanup/beautify code]

Signed-off-by: Stephan Baerwolf <stephan.baerwolf at tu-ilmenau.de>
Signed-off-by: Marcelo Tosatti <mtosatti at redhat.com>

CVE-2012-0045
BugLink: http://bugs.launchpad.net/bugs/917842
(backported from commit bdb42f5afebe208eae90406959383856ae2caf2b upstream)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
 arch/x86/include/asm/kvm_emulate.h |    3 +++
 arch/x86/kvm/x86.c                 |   22 ++++++++++++++++++++++
 2 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 8e37deb..ff22d58 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -158,6 +158,9 @@ struct x86_emulate_ops {
 	int (*set_dr)(int dr, unsigned long value, struct kvm_vcpu *vcpu);
 	int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
+
+	bool (*get_cpuid)(struct kvm_vcpu *vcpu,
+			 u32 *eax, u32 *ebx, u32 *ecx, u32 *edx);
 };
 
 /* Type, address-of, and value of an instruction's operand. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0556e05..bc5d1d2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4212,6 +4212,27 @@ static void emulator_set_segment_selector(u16 sel, int seg,
 	kvm_set_segment(vcpu, &kvm_seg, seg);
 }
 
+static bool emulator_get_cpuid(struct kvm_vcpu *vcpu,
+			       u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
+{
+	struct kvm_cpuid_entry2 *cpuid = NULL;
+
+	if (eax && ecx)
+		cpuid = kvm_find_cpuid_entry(vcpu, *eax, *ecx);
+
+	if (cpuid) {
+		*eax = cpuid->eax;
+		*ecx = cpuid->ecx;
+		if (ebx)
+			*ebx = cpuid->ebx;
+		if (edx)
+			*edx = cpuid->edx;
+		return true;
+	}
+
+	return false;
+}
+
 static struct x86_emulate_ops emulate_ops = {
 	.read_std            = kvm_read_guest_virt_system,
 	.write_std           = kvm_write_guest_virt_system,
@@ -4235,6 +4256,7 @@ static struct x86_emulate_ops emulate_ops = {
 	.set_dr              = emulator_set_dr,
 	.set_msr             = kvm_set_msr,
 	.get_msr             = kvm_get_msr,
+	.get_cpuid           = emulator_get_cpuid,
 };
 
 static void cache_all_regs(struct kvm_vcpu *vcpu)
-- 
1.7.9.1