[01/13] KVM: x86 emulator: add framework for instruction intercepts

Commit Message

Joerg Roedel March 28, 2011, 10:46 a.m. UTC

None

Patch

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 0f52135..92e251d 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -14,6 +14,8 @@ 
 #include <asm/desc_defs.h>
 
 struct x86_emulate_ctxt;
+enum x86_intercept;
+enum x86_intercept_stage;
 
 struct x86_exception {
 	u8 vector;
@@ -62,6 +64,7 @@  struct x86_exception {
 #define X86EMUL_RETRY_INSTR     3 /* retry the instruction for some reason */
 #define X86EMUL_CMPXCHG_FAILED  4 /* cmpxchg did not see expected value */
 #define X86EMUL_IO_NEEDED       5 /* IO is needed to complete emulation */
+#define X86EMUL_INTERCEPTED     6 /* Intercepted by nested VMCB/VMCS */
 
 struct x86_emulate_ops {
 	/*
@@ -158,6 +161,9 @@  struct x86_emulate_ops {
 	int (*set_dr)(int dr, unsigned long value, struct kvm_vcpu *vcpu);
 	int (*set_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 data);
 	int (*get_msr)(struct kvm_vcpu *vcpu, u32 msr_index, u64 *pdata);
+	int (*intercept)(struct x86_emulate_ctxt *ctxt,
+			 enum x86_intercept intercept,
+			 enum x86_intercept_stage stage);
 };
 
 /* Type, address-of, and value of an instruction's operand. */
@@ -197,6 +203,7 @@  struct read_cache {
 struct decode_cache {
 	u8 twobyte;
 	u8 b;
+	u8 intercept;
 	u8 lock_prefix;
 	u8 rep_prefix;
 	u8 op_bytes;
@@ -238,6 +245,7 @@  struct x86_emulate_ctxt {
 	/* interruptibility state, as a result of execution of STI or MOV SS */
 	int interruptibility;
 
+	bool guest_mode; /* guest running a nested guest */
 	bool perm_ok; /* do not check permissions if true */
 	bool only_vendor_specific_insn;
 
@@ -259,6 +267,18 @@  struct x86_emulate_ctxt {
 #define X86EMUL_MODE_PROT32   4	/* 32-bit protected mode. */
 #define X86EMUL_MODE_PROT64   8	/* 64-bit (long) mode.    */
 
+enum x86_intercept_stage {
+	X86_ICPT_PRE_EXCEPT,
+	X86_ICPT_POST_EXCEPT,
+	X86_ICPT_POST_MEMACCESS,
+};
+
+enum x86_intercept {
+	x86_intercept_none,
+
+	nr_x86_intercepts
+};
+
 /* Host execution mode. */
 #if defined(CONFIG_X86_32)
 #define X86EMUL_MODE_HOST X86EMUL_MODE_PROT32
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 14c5ad5..1c574ae 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -102,6 +102,7 @@ 
 
 struct opcode {
 	u32 flags;
+	u8 intercept;
 	union {
 		int (*execute)(struct x86_emulate_ctxt *ctxt);
 		struct opcode *group;
@@ -2326,10 +2327,13 @@  static int em_mov(struct x86_emulate_ctxt *ctxt)
 }
 
 #define D(_y) { .flags = (_y) }
+#define DI(_y, _i) { .flags = (_y), .intercept = x86_intercept_##_i }
 #define N    D(0)
 #define G(_f, _g) { .flags = ((_f) | Group), .u.group = (_g) }
 #define GD(_f, _g) { .flags = ((_f) | Group | GroupDual), .u.gdual = (_g) }
 #define I(_f, _e) { .flags = (_f), .u.execute = (_e) }
+#define II(_f, _e, _i) \
+	{ .flags = (_f), .u.execute = (_e), .intercept = x86_intercept_##_i }
 
 #define D2bv(_f)      D((_f) | ByteOp), D(_f)
 #define I2bv(_f, _e)  I((_f) | ByteOp, _e), I(_f, _e)
@@ -2745,6 +2749,7 @@  done_prefixes:
 	}
 
 	c->execute = opcode.u.execute;
+	c->intercept = opcode.intercept;
 
 	/* Unrecognised? */
 	if (c->d == 0 || (c->d & Undefined))
@@ -2979,12 +2984,26 @@  x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 		goto done;
 	}
 
+	if (unlikely(ctxt->guest_mode) && c->intercept) {
+		rc = ops->intercept(ctxt, c->intercept,
+				    X86_ICPT_PRE_EXCEPT);
+		if (rc != X86EMUL_CONTINUE)
+			goto done;
+	}
+
 	/* Privileged instruction can be executed only in CPL=0 */
 	if ((c->d & Priv) && ops->cpl(ctxt->vcpu)) {
 		rc = emulate_gp(ctxt, 0);
 		goto done;
 	}
 
+	if (unlikely(ctxt->guest_mode) && c->intercept) {
+		rc = ops->intercept(ctxt, c->intercept,
+				    X86_ICPT_POST_EXCEPT);
+		if (rc != X86EMUL_CONTINUE)
+			goto done;
+	}
+
 	if (c->rep_prefix && (c->d & String)) {
 		/* All REP prefixes have the same first termination condition */
 		if (address_mask(c, c->regs[VCPU_REGS_RCX]) == 0) {
@@ -3023,6 +3042,13 @@  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);
+		if (rc != X86EMUL_CONTINUE)
+			goto done;
+	}
+
 	if (c->execute) {
 		rc = c->execute(ctxt);
 		if (rc != X86EMUL_CONTINUE)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bfd7763..829ea7c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4242,6 +4242,13 @@  static void emulator_set_segment_selector(u16 sel, int seg,
 	kvm_set_segment(vcpu, &kvm_seg, seg);
 }
 
+static int emulator_intercept(struct x86_emulate_ctxt *ctxt,
+			      enum x86_intercept intercept,
+			      enum x86_intercept_stage stage)
+{
+	return X86EMUL_CONTINUE;
+}
+
 static struct x86_emulate_ops emulate_ops = {
 	.read_std            = kvm_read_guest_virt_system,
 	.write_std           = kvm_write_guest_virt_system,
@@ -4265,6 +4272,7 @@  static struct x86_emulate_ops emulate_ops = {
 	.set_dr              = emulator_set_dr,
 	.set_msr             = kvm_set_msr,
 	.get_msr             = kvm_get_msr,
+	.intercept           = emulator_intercept,
 };
 
 static void cache_all_regs(struct kvm_vcpu *vcpu)
@@ -4319,6 +4327,7 @@  static void init_emulate_ctxt(struct kvm_vcpu *vcpu)
 		? X86EMUL_MODE_VM86 : cs_l
 		? X86EMUL_MODE_PROT64 :	cs_db
 		? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;
+	vcpu->arch.emulate_ctxt.guest_mode = is_guest_mode(vcpu);
 	memset(c, 0, sizeof(struct decode_cache));
 	memcpy(c->regs, vcpu->arch.regs, sizeof c->regs);
 }