Patchwork [Lucid,1/2] KVM: x86: extend "struct x86_emulate_ops" with "get_cpuid"

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Submitter Stefan Bader
Date March 14, 2012, 10:18 p.m.
Message ID <1331763526-32743-2-git-send-email-stefan.bader@canonical.com>
Download mbox | patch
Permalink /patch/146743/
State New
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Comments

Stefan Bader - March 14, 2012, 10:18 p.m.
From 0aa5ac57d2dcdca1e1c4ec37d6164063766831ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stephan=20B=C3=A4rwolf?= <stephan.baerwolf@tu-ilmenau.de>
Date: Thu, 12 Jan 2012 16:43:03 +0100
Subject: [PATCH 1/2] 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@tu-ilmenau.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

CVE-2012-0045
BugLink: http://bugs.launchpad.net/bugs/917842
(backported from commit bdb42f5afebe208eae90406959383856ae2caf2b upstream)
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
---
 arch/x86/include/asm/kvm_emulate.h |    2 ++
 arch/x86/kvm/x86.c                 |   22 ++++++++++++++++++++++
 2 files changed, 24 insertions(+), 0 deletions(-)

Patch

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 5ed59ec..5d938f9 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -109,6 +109,8 @@  struct x86_emulate_ops {
 				unsigned int bytes,
 				struct kvm_vcpu *vcpu);
 
+	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 df1cefb..74b1f11 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2871,12 +2871,34 @@  void kvm_report_emulation_failure(struct kvm_vcpu *vcpu, const char *context)
 }
 EXPORT_SYMBOL_GPL(kvm_report_emulation_failure);
 
+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,
 	.fetch               = kvm_fetch_guest_virt,
 	.read_emulated       = emulator_read_emulated,
 	.write_emulated      = emulator_write_emulated,
 	.cmpxchg_emulated    = emulator_cmpxchg_emulated,
+	.get_cpuid           = emulator_get_cpuid,
 };
 
 static void cache_all_regs(struct kvm_vcpu *vcpu)