KVM: Fix mov cr4 #GP at wrong instruction

On Intel, we call skip_emulated_instruction() even if we injected a #GP,
resulting in the #GP pointing at the wrong address.

Fix by injecting the exception and skipping the instruction at the same place,
so we can do just one or the other.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

3 files changed, 5 insertions, 11 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b23708450210..ea8c319cdffc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -599,7 +599,7 @@ int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,
 
 int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
 void kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3);
-void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
+int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4);
 void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8);
 int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val);
 int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val);
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 1baf4b2d98ee..f64d65dc38c6 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3189,8 +3189,8 @@ static int handle_cr(struct kvm_vcpu *vcpu)
                         skip_emulated_instruction(vcpu);
                         return 1;
                 case 4:
-                        kvm_set_cr4(vcpu, val);
-                        skip_emulated_instruction(vcpu);
+                        err = kvm_set_cr4(vcpu, val);
+                        complete_insn_gp(vcpu, err);
                         return 1;
                 case 8: {
                                 u8 cr8_prev = kvm_get_cr8(vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 05e9b5dde646..ed3af15d4404 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -531,7 +531,7 @@ static void update_cpuid(struct kvm_vcpu *vcpu)
         }
 }
 
-int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
+int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {
         unsigned long old_cr4 = kvm_read_cr4(vcpu);
         unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
@@ -563,12 +563,6 @@ int __kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 
         return 0;
 }
-
-void kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
-{
-        if (__kvm_set_cr4(vcpu, cr4))
-                kvm_inject_gp(vcpu, 0);
-}
 EXPORT_SYMBOL_GPL(kvm_set_cr4);
 
 static int __kvm_set_cr3(struct kvm_vcpu *vcpu, unsigned long cr3)
@@ -3735,7 +3729,7 @@ static int emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
                 res = __kvm_set_cr3(vcpu, val);
                 break;
         case 4:
-                res = __kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
+                res = kvm_set_cr4(vcpu, mk_cr_64(kvm_read_cr4(vcpu), val));
                 break;
         case 8:
                 res = __kvm_set_cr8(vcpu, val & 0xfUL);