KVM: Fix mov cr0 #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>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 91631b8..b237084 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -597,7 +597,7 @@ int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector, int seg);
 int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int reason,
                    bool has_error_code, u32 error_code);
 
-void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0);
+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);
 void kvm_set_cr8(struct kvm_vcpu *vcpu, unsigned long cr8);

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2ae0c39..6d1616d 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -807,7 +807,7 @@ static void init_vmcb(struct vcpu_svm *svm)
         * svm_set_cr0() sets PG and WP and clears NW and CD on save->cr0.
         */
        svm->vcpu.arch.cr0 = X86_CR0_NW | X86_CR0_CD | X86_CR0_ET;
-       kvm_set_cr0(&svm->vcpu, svm->vcpu.arch.cr0);
+       (void)kvm_set_cr0(&svm->vcpu, svm->vcpu.arch.cr0);
 
        save->cr4 = X86_CR4_PAE;
        /* rdx = ?? */

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 864a1b6..1baf4b2 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3157,11 +3157,20 @@ vmx_patch_hypercall(struct kvm_vcpu *vcpu, unsigned char *hypercall)
        hypercall[2] = 0xc1;
 }
 
+static void complete_insn_gp(struct kvm_vcpu *vcpu, int err)
+{
+       if (err)
+               kvm_inject_gp(vcpu, 0);
+       else
+               skip_emulated_instruction(vcpu);
+}
+
 static int handle_cr(struct kvm_vcpu *vcpu)
 {
        unsigned long exit_qualification, val;
        int cr;
        int reg;
+       int err;
 
        exit_qualification = vmcs_readl(EXIT_QUALIFICATION);
        cr = exit_qualification & 15;
@@ -3172,8 +3181,8 @@ static int handle_cr(struct kvm_vcpu *vcpu)
                trace_kvm_cr_write(cr, val);
                switch (cr) {
                case 0:
-                       kvm_set_cr0(vcpu, val);
-                       skip_emulated_instruction(vcpu);
+                       err = kvm_set_cr0(vcpu, val);
+                       complete_insn_gp(vcpu, err);
                        return 1;
                case 3:
                        kvm_set_cr3(vcpu, val);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b5e6447..05e9b5d 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -425,7 +425,7 @@ out:
        return changed;
 }
 
-static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
+int kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
 {
        unsigned long old_cr0 = kvm_read_cr0(vcpu);
        unsigned long update_bits = X86_CR0_PG | X86_CR0_WP |
@@ -468,17 +468,11 @@ static int __kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
                kvm_mmu_reset_context(vcpu);
        return 0;
 }
-
-void kvm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
-{
-       if (__kvm_set_cr0(vcpu, cr0))
-               kvm_inject_gp(vcpu, 0);
-}
 EXPORT_SYMBOL_GPL(kvm_set_cr0);
 
 void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw)
 {
-       kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0eul) | (msw & 0x0f));
+       (void)kvm_set_cr0(vcpu, kvm_read_cr0_bits(vcpu, ~0x0eul) | (msw & 0x0f));
 }
 EXPORT_SYMBOL_GPL(kvm_lmsw);
 
@@ -3732,7 +3726,7 @@ static int emulator_set_cr(int cr, unsigned long val, struct kvm_vcpu *vcpu)
 
        switch (cr) {
        case 0:
-               res = __kvm_set_cr0(vcpu, mk_cr_64(kvm_read_cr0(vcpu), val));
+               res = kvm_set_cr0(vcpu, mk_cr_64(kvm_read_cr0(vcpu), val));
                break;
        case 2:
                vcpu->arch.cr2 = val;