KVM: x86: Add x86 callback for intercept check

This patch adds a callback into kvm_x86_ops so that svm and
vmx code can do intercept checks on emulated instructions.

Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>

Author: joergroedel

arch/x86/include/asm/kvm_emulate.h

@@ -25,6 +25,24 @@ struct x86_exception {
 	u64 address; /* cr2 or nested page fault gpa */
 };
 
+/*
+ * This struct is used to carry enough information from the instruction
+ * decoder to main KVM so that a decision can be made whether the
+ * instruction needs to be intercepted or not.
+ */
+struct x86_instruction_info {
+	u8  intercept;          /* which intercept                      */
+	u8  rep_prefix;         /* rep prefix?                          */
+	u8  modrm_mod;		/* mod part of modrm			*/
+	u8  modrm_reg;          /* index of register used               */
+	u8  modrm_rm;		/* rm part of modrm			*/
+	u64 src_val;            /* value of source operand              */
+	u8  src_bytes;          /* size of source operand               */
+	u8  dst_bytes;          /* size of destination operand          */
+	u8  ad_bytes;           /* size of src/dst address              */
+	u64 next_rip;           /* rip following the instruction        */
+};
+
 /*
  * x86_emulate_ops:
  *
@@ -163,8 +181,8 @@ struct x86_emulate_ops {
 	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
 	void (*get_fpu)(struct x86_emulate_ctxt *ctxt); /* disables preempt */
 	void (*put_fpu)(struct x86_emulate_ctxt *ctxt); /* reenables preempt */
-	int (*intercept)(struct x86_emulate_ctxt *ctxt,
-			 enum x86_intercept intercept,
+	int (*intercept)(struct kvm_vcpu *vcpu,
+			 struct x86_instruction_info *info,
 			 enum x86_intercept_stage stage);
 };
 

arch/x86/include/asm/kvm_host.h

@@ -505,6 +505,8 @@ struct kvm_vcpu_stat {
 	u32 nmi_injections;
 };
 
+struct x86_instruction_info;
+
 struct kvm_x86_ops {
 	int (*cpu_has_kvm_support)(void);          /* __init */
 	int (*disabled_by_bios)(void);             /* __init */
@@ -592,6 +594,11 @@ struct kvm_x86_ops {
 	void (*write_tsc_offset)(struct kvm_vcpu *vcpu, u64 offset);
 
 	void (*get_exit_info)(struct kvm_vcpu *vcpu, u64 *info1, u64 *info2);
+
+	int (*check_intercept)(struct kvm_vcpu *vcpu,
+			       struct x86_instruction_info *info,
+			       enum x86_intercept_stage stage);
+
 	const struct trace_print_flags *exit_reasons_str;
 };
 

arch/x86/kvm/emulate.c

@@ -408,6 +408,26 @@ struct gprefix {
 	(_eip) += (_size);						\
 })
 
+static int emulator_check_intercept(struct x86_emulate_ctxt *ctxt,
+				    enum x86_intercept intercept,
+				    enum x86_intercept_stage stage)
+{
+	struct x86_instruction_info info = {
+		.intercept  = intercept,
+		.rep_prefix = ctxt->decode.rep_prefix,
+		.modrm_mod  = ctxt->decode.modrm_mod,
+		.modrm_reg  = ctxt->decode.modrm_reg,
+		.modrm_rm   = ctxt->decode.modrm_rm,
+		.src_val    = ctxt->decode.src.val64,
+		.src_bytes  = ctxt->decode.src.bytes,
+		.dst_bytes  = ctxt->decode.dst.bytes,
+		.ad_bytes   = ctxt->decode.ad_bytes,
+		.next_rip   = ctxt->eip,
+	};
+
+	return ctxt->ops->intercept(ctxt->vcpu, &info, stage);
+}
+
 static inline unsigned long ad_mask(struct decode_cache *c)
 {
 	return (1UL << (c->ad_bytes << 3)) - 1;
@@ -3132,8 +3152,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 	}
 
 	if (unlikely(ctxt->guest_mode) && c->intercept) {
-		rc = ops->intercept(ctxt, c->intercept,
-				    X86_ICPT_PRE_EXCEPT);
+		rc = emulator_check_intercept(ctxt, c->intercept,
+					      X86_ICPT_PRE_EXCEPT);
 		if (rc != X86EMUL_CONTINUE)
 			goto done;
 	}
@@ -3158,8 +3178,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 	}
 
 	if (unlikely(ctxt->guest_mode) && c->intercept) {
-		rc = ops->intercept(ctxt, c->intercept,
-				    X86_ICPT_POST_EXCEPT);
+		rc = emulator_check_intercept(ctxt, c->intercept,
+					      X86_ICPT_POST_EXCEPT);
 		if (rc != X86EMUL_CONTINUE)
 			goto done;
 	}
@@ -3203,8 +3223,8 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 special_insn:
 
 	if (unlikely(ctxt->guest_mode) && c->intercept) {
-		rc = ops->intercept(ctxt, c->intercept,
-				    X86_ICPT_POST_MEMACCESS);
+		rc = emulator_check_intercept(ctxt, c->intercept,
+					      X86_ICPT_POST_MEMACCESS);
 		if (rc != X86EMUL_CONTINUE)
 			goto done;
 	}

arch/x86/kvm/svm.c

@@ -3868,6 +3868,13 @@ static void svm_fpu_deactivate(struct kvm_vcpu *vcpu)
 	update_cr0_intercept(svm);
 }
 
+static int svm_check_intercept(struct kvm_vcpu *vcpu,
+			       struct x86_instruction_info *info,
+			       enum x86_intercept_stage stage)
+{
+	return X86EMUL_CONTINUE;
+}
+
 static struct kvm_x86_ops svm_x86_ops = {
 	.cpu_has_kvm_support = has_svm,
 	.disabled_by_bios = is_disabled,
@@ -3953,6 +3960,8 @@ static struct kvm_x86_ops svm_x86_ops = {
 	.adjust_tsc_offset = svm_adjust_tsc_offset,
 
 	.set_tdp_cr3 = set_tdp_cr3,
+
+	.check_intercept = svm_check_intercept,
 };
 
 static int __init svm_init(void)

arch/x86/kvm/vmx.c

@@ -4409,6 +4409,13 @@ static void vmx_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
 {
 }
 
+static int vmx_check_intercept(struct kvm_vcpu *vcpu,
+			       struct x86_instruction_info *info,
+			       enum x86_intercept_stage stage)
+{
+	return X86EMUL_CONTINUE;
+}
+
 static struct kvm_x86_ops vmx_x86_ops = {
 	.cpu_has_kvm_support = cpu_has_kvm_support,
 	.disabled_by_bios = vmx_disabled_by_bios,
@@ -4494,6 +4501,8 @@ static struct kvm_x86_ops vmx_x86_ops = {
 	.adjust_tsc_offset = vmx_adjust_tsc_offset,
 
 	.set_tdp_cr3 = vmx_set_cr3,
+
+	.check_intercept = vmx_check_intercept,
 };
 
 static int __init vmx_init(void)

arch/x86/kvm/x86.c

@@ -4297,11 +4297,11 @@ static void emulator_put_fpu(struct x86_emulate_ctxt *ctxt)
 	preempt_enable();
 }
 
-static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
-			      enum x86_intercept intercept,
+static int emulator_intercept(struct kvm_vcpu *vcpu,
+			      struct x86_instruction_info *info,
 			      enum x86_intercept_stage stage)
 {
-	return X86EMUL_CONTINUE;
+	return kvm_x86_ops->check_intercept(vcpu, info, stage);
 }
 
 static struct x86_emulate_ops emulate_ops = {