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

[Stephan Bärwolf <stephan.baerwolf@xxxxxxxxxxxxx>]

>From c603d51a02539c89dec05fd54de336b282b1cc12 Mon Sep 17 00:00:00 2001
From: Stephan Baerwolf <stephan.baerwolf@xxxxxxxxxxxxx>
Date: Sun, 8 Jan 2012 23:25:59 +0000
Subject: [PATCH 1/2] KVM: 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.

Signed-off-by: Stephan Baerwolf <stephan.baerwolf@xxxxxxxxxxxxx>
---
 arch/x86/include/asm/kvm_emulate.h |    4 ++++
 arch/x86/kvm/x86.c                 |   21 +++++++++++++++++++++
 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 a026507..b172bf4 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -189,6 +189,10 @@ struct x86_emulate_ops {
     int (*intercept)(struct x86_emulate_ctxt *ctxt,
              struct x86_instruction_info *info,
              enum x86_intercept_stage stage);
+
+    /* retrieve ctxt's vcpu's cpuid */
+    bool (*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/x86.c b/arch/x86/kvm/x86.c
index 4c938da..6181783 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4655,6 +4655,26 @@ 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,
+                         u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
+{
+    struct kvm_cpuid_entry2 *cpuid = NULL;
+
+    if ((ctxt) && (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;
+}
+
 static struct x86_emulate_ops emulate_ops = {
     .read_std            = kvm_read_guest_virt_system,
     .write_std           = kvm_write_guest_virt_system,
@@ -4685,6 +4705,7 @@ static struct x86_emulate_ops emulate_ops = {
     .get_fpu             = emulator_get_fpu,
     .put_fpu             = emulator_put_fpu,
     .intercept           = emulator_intercept,
+    .get_cpuid           = emulator_get_cpuid,
 };
 
 static void cache_all_regs(struct kvm_vcpu *vcpu)
-- 
1.7.3.4


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