[PATCH] kvm: x86: svm: remove SVM_EXIT_READ_CR* intercepts

[Joel Schopp]

There isn't really a valid reason for kvm to intercept cr* reads
on svm hardware.  The current kvm code just ends up returning
the register

Signed-off-by: Joel Schopp <joel.schopp@xxxxxxx>
---
 arch/x86/kvm/svm.c |   41 ++++-------------------------------------
 1 file changed, 4 insertions(+), 37 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index cc618c8..c3d10e6 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1090,9 +1090,6 @@ static void init_vmcb(struct vcpu_svm *svm)
 	svm->vcpu.fpu_active = 1;
 	svm->vcpu.arch.hflags = 0;
 
-	set_cr_intercept(svm, INTERCEPT_CR0_READ);
-	set_cr_intercept(svm, INTERCEPT_CR3_READ);
-	set_cr_intercept(svm, INTERCEPT_CR4_READ);
 	set_cr_intercept(svm, INTERCEPT_CR0_WRITE);
 	set_cr_intercept(svm, INTERCEPT_CR3_WRITE);
 	set_cr_intercept(svm, INTERCEPT_CR4_WRITE);
@@ -1174,7 +1171,6 @@ static void init_vmcb(struct vcpu_svm *svm)
 		control->nested_ctl = 1;
 		clr_intercept(svm, INTERCEPT_INVLPG);
 		clr_exception_intercept(svm, PF_VECTOR);
-		clr_cr_intercept(svm, INTERCEPT_CR3_READ);
 		clr_cr_intercept(svm, INTERCEPT_CR3_WRITE);
 		save->g_pat = 0x0007040600070406ULL;
 		save->cr3 = 0;
@@ -2968,29 +2964,10 @@ static int cr_interception(struct vcpu_svm *svm)
 			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 = kvm_read_cr3(&svm->vcpu);
-			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);
+	} else { /* mov from cr, should never trap in svm */
+		WARN(1, "unhandled read from CR%d", cr);
+		kvm_queue_exception(&svm->vcpu, UD_VECTOR);
+		return 1;
 	}
 	kvm_complete_insn_gp(&svm->vcpu, err);
 
@@ -3321,10 +3298,6 @@ static int mwait_interception(struct vcpu_svm *svm)
 }
 
 static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
-	[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]			= cr_interception,
 	[SVM_EXIT_WRITE_CR3]			= cr_interception,
@@ -4151,11 +4124,9 @@ static const struct __x86_intercept {
 	u32 exit_code;
 	enum x86_intercept_stage stage;
 } x86_intercept_map[] = {
-	[x86_intercept_cr_read]		= POST_EX(SVM_EXIT_READ_CR0),
 	[x86_intercept_cr_write]	= POST_EX(SVM_EXIT_WRITE_CR0),
 	[x86_intercept_clts]		= POST_EX(SVM_EXIT_WRITE_CR0),
 	[x86_intercept_lmsw]		= POST_EX(SVM_EXIT_WRITE_CR0),
-	[x86_intercept_smsw]		= POST_EX(SVM_EXIT_READ_CR0),
 	[x86_intercept_dr_read]		= POST_EX(SVM_EXIT_READ_DR0),
 	[x86_intercept_dr_write]	= POST_EX(SVM_EXIT_WRITE_DR0),
 	[x86_intercept_sldt]		= POST_EX(SVM_EXIT_LDTR_READ),
@@ -4221,10 +4192,6 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
 		goto out;
 
 	switch (icpt_info.exit_code) {
-	case SVM_EXIT_READ_CR0:
-		if (info->intercept == x86_intercept_cr_read)
-			icpt_info.exit_code += info->modrm_reg;
-		break;
 	case SVM_EXIT_WRITE_CR0: {
 		unsigned long cr0, val;
 		u64 intercept;

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