KVM: SVM: enhance MOV CR intercept handler
Newer SVM implementations provide the GPR number in the VMCB, so
that the emulation path is no longer necesarry to handle CR
register access intercepts. Implement the handling in svm.c and
use it when the info is provided.
Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index f7087bf..f0ffb81 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
@@ -260,6 +260,8 @@
#define SVM_EXITINFOSHIFT_TS_REASON_JMP 38
#define SVM_EXITINFOSHIFT_TS_HAS_ERROR_CODE 44
+#define SVM_EXITINFO_REG_MASK 0x0F
+
#define SVM_EXIT_READ_CR0 0x000
#define SVM_EXIT_READ_CR3 0x003
#define SVM_EXIT_READ_CR4 0x004
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2830a73..5abaa5b2 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2660,12 +2660,80 @@
return emulate_instruction(&svm->vcpu, 0) == EMULATE_DONE;
}
+#define CR_VALID (1ULL << 63)
+
+static int cr_interception(struct vcpu_svm *svm)
+{
+ int reg, cr;
+ unsigned long val;
+ int err;
+
+ if (!static_cpu_has(X86_FEATURE_DECODEASSISTS))
+ return emulate_on_interception(svm);
+
+ if (unlikely((svm->vmcb->control.exit_info_1 & CR_VALID) == 0))
+ return emulate_on_interception(svm);
+
+ reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
+ cr = svm->vmcb->control.exit_code - SVM_EXIT_READ_CR0;
+
+ err = 0;
+ if (cr >= 16) { /* mov to cr */
+ cr -= 16;
+ val = kvm_register_read(&svm->vcpu, reg);
+ switch (cr) {
+ case 0:
+ err = kvm_set_cr0(&svm->vcpu, val);
+ break;
+ case 3:
+ err = kvm_set_cr3(&svm->vcpu, val);
+ break;
+ case 4:
+ err = kvm_set_cr4(&svm->vcpu, val);
+ break;
+ case 8:
+ err = kvm_set_cr8(&svm->vcpu, val);
+ break;
+ default:
+ WARN(1, "unhandled write to CR%d", cr);
+ kvm_queue_exception(&svm->vcpu, UD_VECTOR);
+ return 1;
+ }
+ } else { /* mov from cr */
+ switch (cr) {
+ case 0:
+ val = kvm_read_cr0(&svm->vcpu);
+ break;
+ case 2:
+ val = svm->vcpu.arch.cr2;
+ break;
+ case 3:
+ val = svm->vcpu.arch.cr3;
+ break;
+ case 4:
+ val = kvm_read_cr4(&svm->vcpu);
+ break;
+ case 8:
+ val = kvm_get_cr8(&svm->vcpu);
+ break;
+ default:
+ WARN(1, "unhandled read from CR%d", cr);
+ kvm_queue_exception(&svm->vcpu, UD_VECTOR);
+ return 1;
+ }
+ kvm_register_write(&svm->vcpu, reg, val);
+ }
+ kvm_complete_insn_gp(&svm->vcpu, err);
+
+ return 1;
+}
+
static int cr0_write_interception(struct vcpu_svm *svm)
{
struct kvm_vcpu *vcpu = &svm->vcpu;
int r;
- r = emulate_instruction(&svm->vcpu, 0);
+ r = cr_interception(svm);
if (svm->nested.vmexit_rip) {
kvm_register_write(vcpu, VCPU_REGS_RIP, svm->nested.vmexit_rip);
@@ -2674,7 +2742,7 @@
svm->nested.vmexit_rip = 0;
}
- return r == EMULATE_DONE;
+ return r;
}
static int cr8_write_interception(struct vcpu_svm *svm)
@@ -2684,13 +2752,13 @@
u8 cr8_prev = kvm_get_cr8(&svm->vcpu);
/* instruction emulation calls kvm_set_cr8() */
- r = emulate_instruction(&svm->vcpu, 0);
+ r = cr_interception(svm);
if (irqchip_in_kernel(svm->vcpu.kvm)) {
clr_cr_intercept(svm, INTERCEPT_CR8_WRITE);
- return r == EMULATE_DONE;
+ return r;
}
if (cr8_prev <= kvm_get_cr8(&svm->vcpu))
- return r == EMULATE_DONE;
+ return r;
kvm_run->exit_reason = KVM_EXIT_SET_TPR;
return 0;
}
@@ -2933,14 +3001,14 @@
}
static int (*svm_exit_handlers[])(struct vcpu_svm *svm) = {
- [SVM_EXIT_READ_CR0] = emulate_on_interception,
- [SVM_EXIT_READ_CR3] = emulate_on_interception,
- [SVM_EXIT_READ_CR4] = emulate_on_interception,
- [SVM_EXIT_READ_CR8] = emulate_on_interception,
+ [SVM_EXIT_READ_CR0] = cr_interception,
+ [SVM_EXIT_READ_CR3] = cr_interception,
+ [SVM_EXIT_READ_CR4] = cr_interception,
+ [SVM_EXIT_READ_CR8] = cr_interception,
[SVM_EXIT_CR0_SEL_WRITE] = emulate_on_interception,
[SVM_EXIT_WRITE_CR0] = cr0_write_interception,
- [SVM_EXIT_WRITE_CR3] = emulate_on_interception,
- [SVM_EXIT_WRITE_CR4] = emulate_on_interception,
+ [SVM_EXIT_WRITE_CR3] = cr_interception,
+ [SVM_EXIT_WRITE_CR4] = cr_interception,
[SVM_EXIT_WRITE_CR8] = cr8_write_interception,
[SVM_EXIT_READ_DR0] = emulate_on_interception,
[SVM_EXIT_READ_DR1] = emulate_on_interception,
