[PATCH 05/13] KVM: SVM: Add intercept check for emulated cr accesses

[Joerg Roedel <joerg.roedel@xxxxxxx>]

This patch adds all necessary intercept checks for
instructions that access the crX registers.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
 arch/x86/include/asm/kvm_emulate.h |    3 +
 arch/x86/kvm/emulate.c             |    8 ++-
 arch/x86/kvm/svm.c                 |   80 +++++++++++++++++++++++++++++++++++-
 3 files changed, 87 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 7960eeb..c1489e1 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -275,6 +275,9 @@ enum x86_intercept_stage {
 
 enum x86_intercept {
 	x86_intercept_none,
+	x86_intercept_cr_read,
+	x86_intercept_cr_write,
+	x86_intercept_clts,
 	x86_intercept_lmsw,
 	x86_intercept_smsw,
 	x86_intercept_lidt,
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 078acc4..384cfa2 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2503,14 +2503,16 @@ static struct opcode opcode_table[256] = {
 static struct opcode twobyte_table[256] = {
 	/* 0x00 - 0x0F */
 	N, GD(0, &group7), N, N,
-	N, D(ImplicitOps | VendorSpecific), D(ImplicitOps | Priv), N,
+	N, D(ImplicitOps | VendorSpecific), DI(ImplicitOps | Priv, clts), N,
 	DI(ImplicitOps | Priv, invd), DI(ImplicitOps | Priv, wbinvd), N, N,
 	N, D(ImplicitOps | ModRM), N, N,
 	/* 0x10 - 0x1F */
 	N, N, N, N, N, N, N, N, D(ImplicitOps | ModRM), N, N, N, N, N, N, N,
 	/* 0x20 - 0x2F */
-	D(ModRM | DstMem | Priv | Op3264), D(ModRM | DstMem | Priv | Op3264),
-	D(ModRM | SrcMem | Priv | Op3264), D(ModRM | SrcMem | Priv | Op3264),
+	DI(ModRM | DstMem | Priv | Op3264, cr_read),
+	D(ModRM | DstMem | Priv | Op3264),
+	DI(ModRM | SrcMem | Priv | Op3264, cr_write),
+	D(ModRM | SrcMem | Priv | Op3264),
 	N, N, N, N,
 	N, N, N, N, N, N, N, N,
 	/* 0x30 - 0x3F */
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b36df64..3b6992e 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -3871,11 +3871,89 @@ static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
 	update_cr0_intercept(svm);
 }
 
+#define POST_EX(exit) { .exit_code = (exit), \
+			.stage = x86_icpt_post_except, \
+			.valid = true }
+
+static struct __x86_intercept {
+	u32 exit_code;
+	enum x86_intercept_stage stage;
+	bool valid;
+} 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),
+};
+
+#undef POST_EX
+
 static int svm_check_intercept(struct kvm_vcpu *vcpu,
 			       struct x86_instruction_info *info,
 			       enum x86_intercept_stage stage)
 {
-	return X86EMUL_CONTINUE;
+	struct vcpu_svm *svm = to_svm(vcpu);
+	int vmexit, ret = X86EMUL_CONTINUE;
+	struct __x86_intercept icpt_info;
+	struct vmcb *vmcb = svm->vmcb;
+	int reg;
+
+	if (info->intercept >= ARRAY_SIZE(x86_intercept_map))
+		goto out;
+
+	icpt_info = x86_intercept_map[info->intercept];
+
+	if (!icpt_info.valid || stage != icpt_info.stage)
+		goto out;
+
+	reg = (info->modrm >> 3) & 7;
+
+	switch (icpt_info.exit_code) {
+	case SVM_EXIT_READ_CR0:
+		if (info->intercept == x86_intercept_cr_read)
+			icpt_info.exit_code += reg;
+	case SVM_EXIT_WRITE_CR0: {
+		unsigned long cr0, val;
+		u64 intercept;
+
+		if (info->intercept == x86_intercept_cr_write)
+			icpt_info.exit_code += reg;
+
+		if (icpt_info.exit_code != SVM_EXIT_WRITE_CR0)
+			break;
+
+		intercept = svm->nested.intercept;
+
+		if (!(intercept & (1ULL << INTERCEPT_SELECTIVE_CR0)))
+			break;
+
+		cr0 = vcpu->arch.cr0 & ~SVM_CR0_SELECTIVE_MASK;
+		val = info->src_val  & ~SVM_CR0_SELECTIVE_MASK;
+
+		if (info->intercept == x86_intercept_lmsw) {
+			cr0 &= 0xfUL;
+			val &= 0xfUL;
+		}
+
+		if (cr0 ^ val)
+			icpt_info.exit_code = SVM_EXIT_CR0_SEL_WRITE;
+
+		break;
+	}
+	default:
+		break;
+	}
+
+	vmcb->control.next_rip  = info->next_rip;
+	vmcb->control.exit_code = icpt_info.exit_code;
+	vmexit = nested_svm_exit_handled(svm);
+
+	ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED
+					   : X86EMUL_CONTINUE;
+
+out:
+	return ret;
 }
 
 static struct kvm_x86_ops svm_x86_ops = {
-- 
1.7.1


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