Revamp the x86 instruction emulation in bhyve.

On a nested page table fault the hypervisor will:
- fetch the instruction using the guest %rip and %cr3
- decode the instruction in 'struct vie'
- emulate the instruction in host kernel context for local apic accesses
- any other type of mmio access is punted up to user-space (e.g. ioapic)

The decoded instruction is passed as collateral to the user-space process
that is handling the PAGING exit.

The emulation code is fleshed out to include more addressing modes (e.g. SIB)
and more types of operands (e.g. imm8). The source code is unified into a
single file (vmm_instruction_emul.c) that is compiled into vmm.ko as well
as /usr/sbin/bhyve.

Reviewed by:	grehan
Obtained from:	NetApp

1 files changed, 113 insertions, 0 deletions

diff --git a/sys/amd64/include/vmm_instruction_emul.h b/sys/amd64/include/vmm_instruction_emul.h
new file mode 100644
index 0000000..4cc494b
--- /dev/null
+++ b/sys/amd64/include/vmm_instruction_emul.h
@@ -0,0 +1,113 @@
+/*-
+ * Copyright (c) 2012 NetApp, Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY NETAPP, INC ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL NETAPP, INC OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_VMM_INSTRUCTION_EMUL_H_
+#define	_VMM_INSTRUCTION_EMUL_H_
+
+/*
+ * The data structures 'vie' and 'vie_op' are meant to be opaque to the
+ * consumers of instruction decoding. The only reason why their contents
+ * need to be exposed is because they are part of the 'vm_exit' structure.
+ */
+struct vie_op {
+	uint8_t		op_byte;	/* actual opcode byte */
+	uint8_t		op_type;	/* type of operation (e.g. MOV) */
+	uint16_t	op_flags;
+};
+
+#define	VIE_INST_SIZE	15
+struct vie {
+	uint8_t		inst[VIE_INST_SIZE];	/* instruction bytes */
+	uint8_t		num_valid;		/* size of the instruction */
+	uint8_t		num_processed;
+
+	uint8_t		rex_w:1,		/* REX prefix */
+			rex_r:1,
+			rex_x:1,
+			rex_b:1;
+
+	uint8_t		mod:2,			/* ModRM byte */
+			reg:4,
+			rm:4;
+
+	uint8_t		ss:2,			/* SIB byte */
+			index:4,
+			base:4;
+
+	uint8_t		disp_bytes;
+	uint8_t		imm_bytes;
+
+	uint8_t		scale;
+	int		base_register;		/* VM_REG_GUEST_xyz */
+	int		index_register;		/* VM_REG_GUEST_xyz */
+
+	int64_t		displacement;		/* optional addr displacement */
+	int64_t		immediate;		/* optional immediate operand */
+
+	uint8_t		decoded;	/* set to 1 if successfully decoded */
+
+	struct vie_op	op;			/* opcode description */
+};
+
+/*
+ * Callback functions to read and write memory regions.
+ */
+typedef int (*mem_region_read_t)(void *vm, int cpuid, uint64_t gpa,
+				 uint64_t *rval, int rsize, void *arg);
+
+typedef int (*mem_region_write_t)(void *vm, int cpuid, uint64_t gpa,
+				  uint64_t wval, int wsize, void *arg);
+
+/*
+ * Emulate the decoded 'vie' instruction.
+ *
+ * The callbacks 'mrr' and 'mrw' emulate reads and writes to the memory region
+ * containing 'gpa'. 'mrarg' is an opaque argument that is passed into the
+ * callback functions.
+ *
+ * 'void *vm' should be 'struct vm *' when called from kernel context and
+ * 'struct vmctx *' when called from user context.
+ * s
+ */
+int vmm_emulate_instruction(void *vm, int cpuid, uint64_t gpa, struct vie *vie,
+			    mem_region_read_t mrr, mem_region_write_t mrw,
+			    void *mrarg);
+
+#ifdef _KERNEL
+/*
+ * APIs to fetch and decode the instruction from nested page fault handler.
+ */
+int vmm_fetch_instruction(struct vm *vm, int cpuid,
+			  uint64_t rip, int inst_length, uint64_t cr3,
+			  struct vie *vie);
+
+int vmm_decode_instruction(struct vm *vm, int cpuid,
+			   uint64_t gla, struct vie *vie);
+#endif	/* _KERNEL */
+
+#endif	/* _VMM_INSTRUCTION_EMUL_H_ */