From cae3797a4639898f339fad57c7e12d270ec91a6c Mon Sep 17 00:00:00 2001
From: Andre Przywara <andre.przywara@amd.com>
Date: Tue, 21 Dec 2010 11:12:05 +0100
Subject: KVM: SVM: enhance mov DR intercept handler

Newer SVM implementations provide the GPR number in the VMCB, so
that the emulation path is no longer necesarry to handle debug
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/kvm/svm.c b/arch/x86/kvm/svm.c
index 5abaa5b2..d84f6a7 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -2745,6 +2745,30 @@ static int cr0_write_interception(struct vcpu_svm *svm)
 	return r;
 }
 
+static int dr_interception(struct vcpu_svm *svm)
+{
+	int reg, dr;
+	unsigned long val;
+	int err;
+
+	if (!boot_cpu_has(X86_FEATURE_DECODEASSISTS))
+		return emulate_on_interception(svm);
+
+	reg = svm->vmcb->control.exit_info_1 & SVM_EXITINFO_REG_MASK;
+	dr = svm->vmcb->control.exit_code - SVM_EXIT_READ_DR0;
+
+	if (dr >= 16) { /* mov to DRn */
+		val = kvm_register_read(&svm->vcpu, reg);
+		kvm_set_dr(&svm->vcpu, dr - 16, val);
+	} else {
+		err = kvm_get_dr(&svm->vcpu, dr, &val);
+		if (!err)
+			kvm_register_write(&svm->vcpu, reg, val);
+	}
+
+	return 1;
+}
+
 static int cr8_write_interception(struct vcpu_svm *svm)
 {
 	struct kvm_run *kvm_run = svm->vcpu.run;
@@ -3010,22 +3034,22 @@ static int (*svm_exit_handlers[])(struct vcpu_svm *svm) = {
 	[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,
-	[SVM_EXIT_READ_DR2]			= emulate_on_interception,
-	[SVM_EXIT_READ_DR3]			= emulate_on_interception,
-	[SVM_EXIT_READ_DR4]			= emulate_on_interception,
-	[SVM_EXIT_READ_DR5]			= emulate_on_interception,
-	[SVM_EXIT_READ_DR6]			= emulate_on_interception,
-	[SVM_EXIT_READ_DR7]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR0]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR1]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR2]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR3]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR4]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR5]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR6]			= emulate_on_interception,
-	[SVM_EXIT_WRITE_DR7]			= emulate_on_interception,
+	[SVM_EXIT_READ_DR0]			= dr_interception,
+	[SVM_EXIT_READ_DR1]			= dr_interception,
+	[SVM_EXIT_READ_DR2]			= dr_interception,
+	[SVM_EXIT_READ_DR3]			= dr_interception,
+	[SVM_EXIT_READ_DR4]			= dr_interception,
+	[SVM_EXIT_READ_DR5]			= dr_interception,
+	[SVM_EXIT_READ_DR6]			= dr_interception,
+	[SVM_EXIT_READ_DR7]			= dr_interception,
+	[SVM_EXIT_WRITE_DR0]			= dr_interception,
+	[SVM_EXIT_WRITE_DR1]			= dr_interception,
+	[SVM_EXIT_WRITE_DR2]			= dr_interception,
+	[SVM_EXIT_WRITE_DR3]			= dr_interception,
+	[SVM_EXIT_WRITE_DR4]			= dr_interception,
+	[SVM_EXIT_WRITE_DR5]			= dr_interception,
+	[SVM_EXIT_WRITE_DR6]			= dr_interception,
+	[SVM_EXIT_WRITE_DR7]			= dr_interception,
 	[SVM_EXIT_EXCP_BASE + DB_VECTOR]	= db_interception,
 	[SVM_EXIT_EXCP_BASE + BP_VECTOR]	= bp_interception,
 	[SVM_EXIT_EXCP_BASE + UD_VECTOR]	= ud_interception,
-- 
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