1 files changed, 42 insertions, 16 deletions

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 3745e6ccc5b4..6270df58e055 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -80,6 +80,9 @@ static const u32 vmx_msr_index[] = {
 
 #ifdef CONFIG_X86_64
 static unsigned msr_offset_kernel_gs_base;
+#define NR_64BIT_MSRS 4
+#else
+#define NR_64BIT_MSRS 0
 #endif
 
 static inline int is_page_fault(u32 intr_info)
@@ -301,6 +304,32 @@ static void vmx_inject_gp(struct kvm_vcpu *vcpu, unsigned error_code)
 }
 
 /*
+ * Set up the vmcs to automatically save and restore system
+ * msrs.  Don't touch the 64-bit msrs if the guest is in legacy
+ * mode, as fiddling with msrs is very expensive.
+ */
+static void setup_msrs(struct kvm_vcpu *vcpu)
+{
+        int nr_skip, nr_good_msrs;
+
+        if (is_long_mode(vcpu))
+                nr_skip = NR_BAD_MSRS;
+        else
+                nr_skip = NR_64BIT_MSRS;
+        nr_good_msrs = vcpu->nmsrs - nr_skip;
+
+        vmcs_writel(VM_ENTRY_MSR_LOAD_ADDR,
+                    virt_to_phys(vcpu->guest_msrs + nr_skip));
+        vmcs_writel(VM_EXIT_MSR_STORE_ADDR,
+                    virt_to_phys(vcpu->guest_msrs + nr_skip));
+        vmcs_writel(VM_EXIT_MSR_LOAD_ADDR,
+                    virt_to_phys(vcpu->host_msrs + nr_skip));
+        vmcs_write32(VM_EXIT_MSR_STORE_COUNT, nr_good_msrs); /* 22.2.2 */
+        vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, nr_good_msrs);  /* 22.2.2 */
+        vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, nr_good_msrs); /* 22.2.2 */
+}
+
+/*
  * reads and returns guest's timestamp counter "register"
  * guest_tsc = host_tsc + tsc_offset    -- 21.3
  */
@@ -825,6 +854,7 @@ static void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 
                 msr->data = efer & ~EFER_LME;
         }
+        setup_msrs(vcpu);
 }
 
 #endif
@@ -988,7 +1018,6 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
         struct descriptor_table dt;
         int i;
         int ret = 0;
-        int nr_good_msrs;
         extern asmlinkage void kvm_vmx_return(void);
 
         if (!init_rmode_tss(vcpu->kvm)) {
@@ -1140,19 +1169,10 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
                 ++vcpu->nmsrs;
         }
 
-        nr_good_msrs = vcpu->nmsrs - NR_BAD_MSRS;
-        vmcs_writel(VM_ENTRY_MSR_LOAD_ADDR,
-                    virt_to_phys(vcpu->guest_msrs + NR_BAD_MSRS));
-        vmcs_writel(VM_EXIT_MSR_STORE_ADDR,
-                    virt_to_phys(vcpu->guest_msrs + NR_BAD_MSRS));
-        vmcs_writel(VM_EXIT_MSR_LOAD_ADDR,
-                    virt_to_phys(vcpu->host_msrs + NR_BAD_MSRS));
+        setup_msrs(vcpu);
+
         vmcs_write32_fixedbits(MSR_IA32_VMX_EXIT_CTLS, VM_EXIT_CONTROLS,
                                (HOST_IS_64 << 9));  /* 22.2,1, 20.7.1 */
-        vmcs_write32(VM_EXIT_MSR_STORE_COUNT, nr_good_msrs); /* 22.2.2 */
-        vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, nr_good_msrs);  /* 22.2.2 */
-        vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, nr_good_msrs); /* 22.2.2 */
-
 
         /* 22.2.1, 20.8.1 */
         vmcs_write32_fixedbits(MSR_IA32_VMX_ENTRY_CTLS,
@@ -1769,9 +1789,11 @@ again:
         fx_restore(vcpu->guest_fx_image);
 
 #ifdef CONFIG_X86_64
-        save_msrs(vcpu->host_msrs + msr_offset_kernel_gs_base, 1);
+        if (is_long_mode(vcpu)) {
+                save_msrs(vcpu->host_msrs + msr_offset_kernel_gs_base, 1);
+                load_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
+        }
 #endif
-        load_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
 
         asm (
                 /* Store host registers */
@@ -1915,8 +1937,12 @@ again:
         }
         ++kvm_stat.exits;
 
-        save_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
-        load_msrs(vcpu->host_msrs, NR_BAD_MSRS);
+#ifdef CONFIG_X86_64
+        if (is_long_mode(vcpu)) {
+                save_msrs(vcpu->guest_msrs, NR_BAD_MSRS);
+                load_msrs(vcpu->host_msrs, NR_BAD_MSRS);
+        }
+#endif
 
         fx_save(vcpu->guest_fx_image);
         fx_restore(vcpu->host_fx_image);