KVM/MIPS32: Privileged instruction/target branch emulation.

- The Guest kernel is run in UM and privileged instructions cause a trap.
- If the instruction causing the trap is in a branch delay slot, the branch
  needs to be emulated to figure out the PC @ which the guest will resume
  execution.

Signed-off-by: Sanjay Lal <sanjayl@kymasys.com>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 1853 insertions, 0 deletions

diff --git a/arch/mips/kvm/kvm_mips_emul.c b/arch/mips/kvm/kvm_mips_emul.c
new file mode 100644
index 000000000000..4b6274b47f33
--- /dev/null
+++ b/arch/mips/kvm/kvm_mips_emul.c
@@ -0,0 +1,1829 @@
+/*
+* This file is subject to the terms and conditions of the GNU General Public
+* License.  See the file "COPYING" in the main directory of this archive
+* for more details.
+*
+* KVM/MIPS: Instruction/Exception emulation
+*
+* Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
+* Authors: Sanjay Lal <sanjayl@kymasys.com>
+*/
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/fs.h>
+#include <linux/bootmem.h>
+#include <linux/random.h>
+#include <asm/page.h>
+#include <asm/cacheflush.h>
+#include <asm/cpu-info.h>
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+#include <asm/inst.h>
+
+#undef CONFIG_MIPS_MT
+#include <asm/r4kcache.h>
+#define CONFIG_MIPS_MT
+
+#include "kvm_mips_opcode.h"
+#include "kvm_mips_int.h"
+#include "kvm_mips_comm.h"
+
+#include "trace.h"
+
+/*
+ * Compute the return address and do emulate branch simulation, if required.
+ * This function should be called only in branch delay slot active.
+ */
+unsigned long kvm_compute_return_epc(struct kvm_vcpu *vcpu,
+	unsigned long instpc)
+{
+	unsigned int dspcontrol;
+	union mips_instruction insn;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	long epc = instpc;
+	long nextpc = KVM_INVALID_INST;
+
+	if (epc & 3)
+		goto unaligned;
+
+	/*
+	 * Read the instruction
+	 */
+	insn.word = kvm_get_inst((uint32_t *) epc, vcpu);
+
+	if (insn.word == KVM_INVALID_INST)
+		return KVM_INVALID_INST;
+
+	switch (insn.i_format.opcode) {
+		/*
+		 * jr and jalr are in r_format format.
+		 */
+	case spec_op:
+		switch (insn.r_format.func) {
+		case jalr_op:
+			arch->gprs[insn.r_format.rd] = epc + 8;
+			/* Fall through */
+		case jr_op:
+			nextpc = arch->gprs[insn.r_format.rs];
+			break;
+		}
+		break;
+
+		/*
+		 * This group contains:
+		 * bltz_op, bgez_op, bltzl_op, bgezl_op,
+		 * bltzal_op, bgezal_op, bltzall_op, bgezall_op.
+		 */
+	case bcond_op:
+		switch (insn.i_format.rt) {
+		case bltz_op:
+		case bltzl_op:
+			if ((long)arch->gprs[insn.i_format.rs] < 0)
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			nextpc = epc;
+			break;
+
+		case bgez_op:
+		case bgezl_op:
+			if ((long)arch->gprs[insn.i_format.rs] >= 0)
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			nextpc = epc;
+			break;
+
+		case bltzal_op:
+		case bltzall_op:
+			arch->gprs[31] = epc + 8;
+			if ((long)arch->gprs[insn.i_format.rs] < 0)
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			nextpc = epc;
+			break;
+
+		case bgezal_op:
+		case bgezall_op:
+			arch->gprs[31] = epc + 8;
+			if ((long)arch->gprs[insn.i_format.rs] >= 0)
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			nextpc = epc;
+			break;
+		case bposge32_op:
+			if (!cpu_has_dsp)
+				goto sigill;
+
+			dspcontrol = rddsp(0x01);
+
+			if (dspcontrol >= 32) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			} else
+				epc += 8;
+			nextpc = epc;
+			break;
+		}
+		break;
+
+		/*
+		 * These are unconditional and in j_format.
+		 */
+	case jal_op:
+		arch->gprs[31] = instpc + 8;
+	case j_op:
+		epc += 4;
+		epc >>= 28;
+		epc <<= 28;
+		epc |= (insn.j_format.target << 2);
+		nextpc = epc;
+		break;
+
+		/*
+		 * These are conditional and in i_format.
+		 */
+	case beq_op:
+	case beql_op:
+		if (arch->gprs[insn.i_format.rs] ==
+		    arch->gprs[insn.i_format.rt])
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		nextpc = epc;
+		break;
+
+	case bne_op:
+	case bnel_op:
+		if (arch->gprs[insn.i_format.rs] !=
+		    arch->gprs[insn.i_format.rt])
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		nextpc = epc;
+		break;
+
+	case blez_op:		/* not really i_format */
+	case blezl_op:
+		/* rt field assumed to be zero */
+		if ((long)arch->gprs[insn.i_format.rs] <= 0)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		nextpc = epc;
+		break;
+
+	case bgtz_op:
+	case bgtzl_op:
+		/* rt field assumed to be zero */
+		if ((long)arch->gprs[insn.i_format.rs] > 0)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		nextpc = epc;
+		break;
+
+		/*
+		 * And now the FPA/cp1 branch instructions.
+		 */
+	case cop1_op:
+		printk("%s: unsupported cop1_op\n", __func__);
+		break;
+	}
+
+	return nextpc;
+
+unaligned:
+	printk("%s: unaligned epc\n", __func__);
+	return nextpc;
+
+sigill:
+	printk("%s: DSP branch but not DSP ASE\n", __func__);
+	return nextpc;
+}
+
+enum emulation_result update_pc(struct kvm_vcpu *vcpu, uint32_t cause)
+{
+	unsigned long branch_pc;
+	enum emulation_result er = EMULATE_DONE;
+
+	if (cause & CAUSEF_BD) {
+		branch_pc = kvm_compute_return_epc(vcpu, vcpu->arch.pc);
+		if (branch_pc == KVM_INVALID_INST) {
+			er = EMULATE_FAIL;
+		} else {
+			vcpu->arch.pc = branch_pc;
+			kvm_debug("BD update_pc(): New PC: %#lx\n", vcpu->arch.pc);
+		}
+	} else
+		vcpu->arch.pc += 4;
+
+	kvm_debug("update_pc(): New PC: %#lx\n", vcpu->arch.pc);
+
+	return er;
+}
+
+/* Everytime the compare register is written to, we need to decide when to fire
+ * the timer that represents timer ticks to the GUEST.
+ *
+ */
+enum emulation_result kvm_mips_emulate_count(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	enum emulation_result er = EMULATE_DONE;
+
+	/* If COUNT is enabled */
+	if (!(kvm_read_c0_guest_cause(cop0) & CAUSEF_DC)) {
+		hrtimer_try_to_cancel(&vcpu->arch.comparecount_timer);
+		hrtimer_start(&vcpu->arch.comparecount_timer,
+			      ktime_set(0, MS_TO_NS(10)), HRTIMER_MODE_REL);
+	} else {
+		hrtimer_try_to_cancel(&vcpu->arch.comparecount_timer);
+	}
+
+	return er;
+}
+
+enum emulation_result kvm_mips_emul_eret(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	enum emulation_result er = EMULATE_DONE;
+
+	if (kvm_read_c0_guest_status(cop0) & ST0_EXL) {
+		kvm_debug("[%#lx] ERET to %#lx\n", vcpu->arch.pc,
+			  kvm_read_c0_guest_epc(cop0));
+		kvm_clear_c0_guest_status(cop0, ST0_EXL);
+		vcpu->arch.pc = kvm_read_c0_guest_epc(cop0);
+
+	} else if (kvm_read_c0_guest_status(cop0) & ST0_ERL) {
+		kvm_clear_c0_guest_status(cop0, ST0_ERL);
+		vcpu->arch.pc = kvm_read_c0_guest_errorepc(cop0);
+	} else {
+		printk("[%#lx] ERET when MIPS_SR_EXL|MIPS_SR_ERL == 0\n",
+		       vcpu->arch.pc);
+		er = EMULATE_FAIL;
+	}
+
+	return er;
+}
+
+enum emulation_result kvm_mips_emul_wait(struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+
+	kvm_debug("[%#lx] !!!WAIT!!! (%#lx)\n", vcpu->arch.pc,
+		  vcpu->arch.pending_exceptions);
+
+	++vcpu->stat.wait_exits;
+	trace_kvm_exit(vcpu, WAIT_EXITS);
+	if (!vcpu->arch.pending_exceptions) {
+		vcpu->arch.wait = 1;
+		kvm_vcpu_block(vcpu);
+
+		/* We we are runnable, then definitely go off to user space to check if any
+		 * I/O interrupts are pending.
+		 */
+		if (kvm_check_request(KVM_REQ_UNHALT, vcpu)) {
+			clear_bit(KVM_REQ_UNHALT, &vcpu->requests);
+			vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
+		}
+	}
+
+	return er;
+}
+
+/* XXXKYMA: Linux doesn't seem to use TLBR, return EMULATE_FAIL for now so that we can catch
+ * this, if things ever change
+ */
+enum emulation_result kvm_mips_emul_tlbr(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	enum emulation_result er = EMULATE_FAIL;
+	uint32_t pc = vcpu->arch.pc;
+
+	printk("[%#x] COP0_TLBR [%ld]\n", pc, kvm_read_c0_guest_index(cop0));
+	return er;
+}
+
+/* Write Guest TLB Entry @ Index */
+enum emulation_result kvm_mips_emul_tlbwi(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	int index = kvm_read_c0_guest_index(cop0);
+	enum emulation_result er = EMULATE_DONE;
+	struct kvm_mips_tlb *tlb = NULL;
+	uint32_t pc = vcpu->arch.pc;
+
+	if (index < 0 || index >= KVM_MIPS_GUEST_TLB_SIZE) {
+		printk("%s: illegal index: %d\n", __func__, index);
+		printk
+		    ("[%#x] COP0_TLBWI [%d] (entryhi: %#lx, entrylo0: %#lx entrylo1: %#lx, mask: %#lx)\n",
+		     pc, index, kvm_read_c0_guest_entryhi(cop0),
+		     kvm_read_c0_guest_entrylo0(cop0),
+		     kvm_read_c0_guest_entrylo1(cop0),
+		     kvm_read_c0_guest_pagemask(cop0));
+		index = (index & ~0x80000000) % KVM_MIPS_GUEST_TLB_SIZE;
+	}
+
+	tlb = &vcpu->arch.guest_tlb[index];
+#if 1
+	/* Probe the shadow host TLB for the entry being overwritten, if one matches, invalidate it */
+	kvm_mips_host_tlb_inv(vcpu, tlb->tlb_hi);
+#endif
+
+	tlb->tlb_mask = kvm_read_c0_guest_pagemask(cop0);
+	tlb->tlb_hi = kvm_read_c0_guest_entryhi(cop0);
+	tlb->tlb_lo0 = kvm_read_c0_guest_entrylo0(cop0);
+	tlb->tlb_lo1 = kvm_read_c0_guest_entrylo1(cop0);
+
+	kvm_debug
+	    ("[%#x] COP0_TLBWI [%d] (entryhi: %#lx, entrylo0: %#lx entrylo1: %#lx, mask: %#lx)\n",
+	     pc, index, kvm_read_c0_guest_entryhi(cop0),
+	     kvm_read_c0_guest_entrylo0(cop0), kvm_read_c0_guest_entrylo1(cop0),
+	     kvm_read_c0_guest_pagemask(cop0));
+
+	return er;
+}
+
+/* Write Guest TLB Entry @ Random Index */
+enum emulation_result kvm_mips_emul_tlbwr(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	enum emulation_result er = EMULATE_DONE;
+	struct kvm_mips_tlb *tlb = NULL;
+	uint32_t pc = vcpu->arch.pc;
+	int index;
+
+#if 1
+	get_random_bytes(&index, sizeof(index));
+	index &= (KVM_MIPS_GUEST_TLB_SIZE - 1);
+#else
+	index = jiffies % KVM_MIPS_GUEST_TLB_SIZE;
+#endif
+
+	if (index < 0 || index >= KVM_MIPS_GUEST_TLB_SIZE) {
+		printk("%s: illegal index: %d\n", __func__, index);
+		return EMULATE_FAIL;
+	}
+
+	tlb = &vcpu->arch.guest_tlb[index];
+
+#if 1
+	/* Probe the shadow host TLB for the entry being overwritten, if one matches, invalidate it */
+	kvm_mips_host_tlb_inv(vcpu, tlb->tlb_hi);
+#endif
+
+	tlb->tlb_mask = kvm_read_c0_guest_pagemask(cop0);
+	tlb->tlb_hi = kvm_read_c0_guest_entryhi(cop0);
+	tlb->tlb_lo0 = kvm_read_c0_guest_entrylo0(cop0);
+	tlb->tlb_lo1 = kvm_read_c0_guest_entrylo1(cop0);
+
+	kvm_debug
+	    ("[%#x] COP0_TLBWR[%d] (entryhi: %#lx, entrylo0: %#lx entrylo1: %#lx)\n",
+	     pc, index, kvm_read_c0_guest_entryhi(cop0),
+	     kvm_read_c0_guest_entrylo0(cop0),
+	     kvm_read_c0_guest_entrylo1(cop0));
+
+	return er;
+}
+
+enum emulation_result kvm_mips_emul_tlbp(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	long entryhi = kvm_read_c0_guest_entryhi(cop0);
+	enum emulation_result er = EMULATE_DONE;
+	uint32_t pc = vcpu->arch.pc;
+	int index = -1;
+
+	index = kvm_mips_guest_tlb_lookup(vcpu, entryhi);
+
+	kvm_write_c0_guest_index(cop0, index);
+
+	kvm_debug("[%#x] COP0_TLBP (entryhi: %#lx), index: %d\n", pc, entryhi,
+		  index);
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_CP0(uint32_t inst, uint32_t *opc, uint32_t cause,
+		     struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	enum emulation_result er = EMULATE_DONE;
+	int32_t rt, rd, copz, sel, co_bit, op;
+	uint32_t pc = vcpu->arch.pc;
+	unsigned long curr_pc;
+
+	/*
+	 * Update PC and hold onto current PC in case there is
+	 * an error and we want to rollback the PC
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, cause);
+	if (er == EMULATE_FAIL) {
+		return er;
+	}
+
+	copz = (inst >> 21) & 0x1f;
+	rt = (inst >> 16) & 0x1f;
+	rd = (inst >> 11) & 0x1f;
+	sel = inst & 0x7;
+	co_bit = (inst >> 25) & 1;
+
+	/* Verify that the register is valid */
+	if (rd > MIPS_CP0_DESAVE) {
+		printk("Invalid rd: %d\n", rd);
+		er = EMULATE_FAIL;
+		goto done;
+	}
+
+	if (co_bit) {
+		op = (inst) & 0xff;
+
+		switch (op) {
+		case tlbr_op:	/*  Read indexed TLB entry  */
+			er = kvm_mips_emul_tlbr(vcpu);
+			break;
+		case tlbwi_op:	/*  Write indexed  */
+			er = kvm_mips_emul_tlbwi(vcpu);
+			break;
+		case tlbwr_op:	/*  Write random  */
+			er = kvm_mips_emul_tlbwr(vcpu);
+			break;
+		case tlbp_op:	/* TLB Probe */
+			er = kvm_mips_emul_tlbp(vcpu);
+			break;
+		case rfe_op:
+			printk("!!!COP0_RFE!!!\n");
+			break;
+		case eret_op:
+			er = kvm_mips_emul_eret(vcpu);
+			goto dont_update_pc;
+			break;
+		case wait_op:
+			er = kvm_mips_emul_wait(vcpu);
+			break;
+		}
+	} else {
+		switch (copz) {
+		case mfc_op:
+#ifdef CONFIG_KVM_MIPS_DEBUG_COP0_COUNTERS
+			cop0->stat[rd][sel]++;
+#endif
+			/* Get reg */
+			if ((rd == MIPS_CP0_COUNT) && (sel == 0)) {
+				/* XXXKYMA: Run the Guest count register @ 1/4 the rate of the host */
+				vcpu->arch.gprs[rt] = (read_c0_count() >> 2);
+			} else if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) {
+				vcpu->arch.gprs[rt] = 0x0;
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+				kvm_mips_trans_mfc0(inst, opc, vcpu);
+#endif
+			}
+			else {
+				vcpu->arch.gprs[rt] = cop0->reg[rd][sel];
+
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+				kvm_mips_trans_mfc0(inst, opc, vcpu);
+#endif
+			}
+
+			kvm_debug
+			    ("[%#x] MFCz[%d][%d], vcpu->arch.gprs[%d]: %#lx\n",
+			     pc, rd, sel, rt, vcpu->arch.gprs[rt]);
+
+			break;
+
+		case dmfc_op:
+			vcpu->arch.gprs[rt] = cop0->reg[rd][sel];
+			break;
+
+		case mtc_op:
+#ifdef CONFIG_KVM_MIPS_DEBUG_COP0_COUNTERS
+			cop0->stat[rd][sel]++;
+#endif
+			if ((rd == MIPS_CP0_TLB_INDEX)
+			    && (vcpu->arch.gprs[rt] >=
+				KVM_MIPS_GUEST_TLB_SIZE)) {
+				printk("Invalid TLB Index: %ld",
+				       vcpu->arch.gprs[rt]);
+				er = EMULATE_FAIL;
+				break;
+			}
+#define C0_EBASE_CORE_MASK 0xff
+			if ((rd == MIPS_CP0_PRID) && (sel == 1)) {
+				/* Preserve CORE number */
+				kvm_change_c0_guest_ebase(cop0,
+							  ~(C0_EBASE_CORE_MASK),
+							  vcpu->arch.gprs[rt]);
+				printk("MTCz, cop0->reg[EBASE]: %#lx\n",
+				       kvm_read_c0_guest_ebase(cop0));
+			} else if (rd == MIPS_CP0_TLB_HI && sel == 0) {
+				uint32_t nasid =
+				    vcpu->arch.gprs[rt] & ASID_MASK;
+				if ((KSEGX(vcpu->arch.gprs[rt]) != CKSEG0)
+				    &&
+				    ((kvm_read_c0_guest_entryhi(cop0) &
+				      ASID_MASK) != nasid)) {
+
+					kvm_debug
+					    ("MTCz, change ASID from %#lx to %#lx\n",
+					     kvm_read_c0_guest_entryhi(cop0) &
+					     ASID_MASK,
+					     vcpu->arch.gprs[rt] & ASID_MASK);
+
+					/* Blow away the shadow host TLBs */
+					kvm_mips_flush_host_tlb(1);
+				}
+				kvm_write_c0_guest_entryhi(cop0,
+							   vcpu->arch.gprs[rt]);
+			}
+			/* Are we writing to COUNT */
+			else if ((rd == MIPS_CP0_COUNT) && (sel == 0)) {
+				/* Linux doesn't seem to write into COUNT, we throw an error
+				 * if we notice a write to COUNT
+				 */
+				/*er = EMULATE_FAIL; */
+				goto done;
+			} else if ((rd == MIPS_CP0_COMPARE) && (sel == 0)) {
+				kvm_debug("[%#x] MTCz, COMPARE %#lx <- %#lx\n",
+					  pc, kvm_read_c0_guest_compare(cop0),
+					  vcpu->arch.gprs[rt]);
+
+				/* If we are writing to COMPARE */
+				/* Clear pending timer interrupt, if any */
+				kvm_mips_callbacks->dequeue_timer_int(vcpu);
+				kvm_write_c0_guest_compare(cop0,
+							   vcpu->arch.gprs[rt]);
+			} else if ((rd == MIPS_CP0_STATUS) && (sel == 0)) {
+				kvm_write_c0_guest_status(cop0,
+							  vcpu->arch.gprs[rt]);
+				/* Make sure that CU1 and NMI bits are never set */
+				kvm_clear_c0_guest_status(cop0,
+							  (ST0_CU1 | ST0_NMI));
+
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+				kvm_mips_trans_mtc0(inst, opc, vcpu);
+#endif
+			} else {
+				cop0->reg[rd][sel] = vcpu->arch.gprs[rt];
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+				kvm_mips_trans_mtc0(inst, opc, vcpu);
+#endif
+			}
+
+			kvm_debug("[%#x] MTCz, cop0->reg[%d][%d]: %#lx\n", pc,
+				  rd, sel, cop0->reg[rd][sel]);
+			break;
+
+		case dmtc_op:
+			printk
+			    ("!!!!!!![%#lx]dmtc_op: rt: %d, rd: %d, sel: %d!!!!!!\n",
+			     vcpu->arch.pc, rt, rd, sel);
+			er = EMULATE_FAIL;
+			break;
+
+		case mfmcz_op:
+#ifdef KVM_MIPS_DEBUG_COP0_COUNTERS
+			cop0->stat[MIPS_CP0_STATUS][0]++;
+#endif
+			if (rt != 0) {
+				vcpu->arch.gprs[rt] =
+				    kvm_read_c0_guest_status(cop0);
+			}
+			/* EI */
+			if (inst & 0x20) {
+				kvm_debug("[%#lx] mfmcz_op: EI\n",
+					  vcpu->arch.pc);
+				kvm_set_c0_guest_status(cop0, ST0_IE);
+			} else {
+				kvm_debug("[%#lx] mfmcz_op: DI\n",
+					  vcpu->arch.pc);
+				kvm_clear_c0_guest_status(cop0, ST0_IE);
+			}
+
+			break;
+
+		case wrpgpr_op:
+			{
+				uint32_t css =
+				    cop0->reg[MIPS_CP0_STATUS][2] & 0xf;
+				uint32_t pss =
+				    (cop0->reg[MIPS_CP0_STATUS][2] >> 6) & 0xf;
+				/* We don't support any shadow register sets, so SRSCtl[PSS] == SRSCtl[CSS] = 0 */
+				if (css || pss) {
+					er = EMULATE_FAIL;
+					break;
+				}
+				kvm_debug("WRPGPR[%d][%d] = %#lx\n", pss, rd,
+					  vcpu->arch.gprs[rt]);
+				vcpu->arch.gprs[rd] = vcpu->arch.gprs[rt];
+			}
+			break;
+		default:
+			printk
+			    ("[%#lx]MachEmulateCP0: unsupported COP0, copz: 0x%x\n",
+			     vcpu->arch.pc, copz);
+			er = EMULATE_FAIL;
+			break;
+		}
+	}
+
+done:
+	/*
+	 * Rollback PC only if emulation was unsuccessful
+	 */
+	if (er == EMULATE_FAIL) {
+		vcpu->arch.pc = curr_pc;
+	}
+
+dont_update_pc:
+	/*
+	 * This is for special instructions whose emulation
+	 * updates the PC, so do not overwrite the PC under
+	 * any circumstances
+	 */
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_store(uint32_t inst, uint32_t cause,
+		       struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DO_MMIO;
+	int32_t op, base, rt, offset;
+	uint32_t bytes;
+	void *data = run->mmio.data;
+	unsigned long curr_pc;
+
+	/*
+	 * Update PC and hold onto current PC in case there is
+	 * an error and we want to rollback the PC
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, cause);
+	if (er == EMULATE_FAIL)
+		return er;
+
+	rt = (inst >> 16) & 0x1f;
+	base = (inst >> 21) & 0x1f;
+	offset = inst & 0xffff;
+	op = (inst >> 26) & 0x3f;
+
+	switch (op) {
+	case sb_op:
+		bytes = 1;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+		run->mmio.len = bytes;
+		run->mmio.is_write = 1;
+		vcpu->mmio_needed = 1;
+		vcpu->mmio_is_write = 1;
+		*(u8 *) data = vcpu->arch.gprs[rt];
+		kvm_debug("OP_SB: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.host_cp0_badvaddr, vcpu->arch.gprs[rt],
+			  *(uint8_t *) data);
+
+		break;
+
+	case sw_op:
+		bytes = 4;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+
+		run->mmio.len = bytes;
+		run->mmio.is_write = 1;
+		vcpu->mmio_needed = 1;
+		vcpu->mmio_is_write = 1;
+		*(uint32_t *) data = vcpu->arch.gprs[rt];
+
+		kvm_debug("[%#lx] OP_SW: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(uint32_t *) data);
+		break;
+
+	case sh_op:
+		bytes = 2;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+
+		run->mmio.len = bytes;
+		run->mmio.is_write = 1;
+		vcpu->mmio_needed = 1;
+		vcpu->mmio_is_write = 1;
+		*(uint16_t *) data = vcpu->arch.gprs[rt];
+
+		kvm_debug("[%#lx] OP_SH: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(uint32_t *) data);
+		break;
+
+	default:
+		printk("Store not yet supported");
+		er = EMULATE_FAIL;
+		break;
+	}
+
+	/*
+	 * Rollback PC if emulation was unsuccessful
+	 */
+	if (er == EMULATE_FAIL) {
+		vcpu->arch.pc = curr_pc;
+	}
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_load(uint32_t inst, uint32_t cause,
+		      struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DO_MMIO;
+	int32_t op, base, rt, offset;
+	uint32_t bytes;
+
+	rt = (inst >> 16) & 0x1f;
+	base = (inst >> 21) & 0x1f;
+	offset = inst & 0xffff;
+	op = (inst >> 26) & 0x3f;
+
+	vcpu->arch.pending_load_cause = cause;
+	vcpu->arch.io_gpr = rt;
+
+	switch (op) {
+	case lw_op:
+		bytes = 4;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+			er = EMULATE_FAIL;
+			break;
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+
+		run->mmio.len = bytes;
+		run->mmio.is_write = 0;
+		vcpu->mmio_needed = 1;
+		vcpu->mmio_is_write = 0;
+		break;
+
+	case lh_op:
+	case lhu_op:
+		bytes = 2;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+			er = EMULATE_FAIL;
+			break;
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+
+		run->mmio.len = bytes;
+		run->mmio.is_write = 0;
+		vcpu->mmio_needed = 1;
+		vcpu->mmio_is_write = 0;
+
+		if (op == lh_op)
+			vcpu->mmio_needed = 2;
+		else
+			vcpu->mmio_needed = 1;
+
+		break;
+
+	case lbu_op:
+	case lb_op:
+		bytes = 1;
+		if (bytes > sizeof(run->mmio.data)) {
+			kvm_err("%s: bad MMIO length: %d\n", __func__,
+			       run->mmio.len);
+			er = EMULATE_FAIL;
+			break;
+		}
+		run->mmio.phys_addr =
+		    kvm_mips_callbacks->gva_to_gpa(vcpu->arch.
+						   host_cp0_badvaddr);
+		if (run->mmio.phys_addr == KVM_INVALID_ADDR) {
+			er = EMULATE_FAIL;
+			break;
+		}
+
+		run->mmio.len = bytes;
+		run->mmio.is_write = 0;
+		vcpu->mmio_is_write = 0;
+
+		if (op == lb_op)
+			vcpu->mmio_needed = 2;
+		else
+			vcpu->mmio_needed = 1;
+
+		break;
+
+	default:
+		printk("Load not yet supported");
+		er = EMULATE_FAIL;
+		break;
+	}
+
+	return er;
+}
+
+int kvm_mips_sync_icache(unsigned long va, struct kvm_vcpu *vcpu)
+{
+	unsigned long offset = (va & ~PAGE_MASK);
+	struct kvm *kvm = vcpu->kvm;
+	unsigned long pa;
+	gfn_t gfn;
+	pfn_t pfn;
+
+	gfn = va >> PAGE_SHIFT;
+
+	if (gfn >= kvm->arch.guest_pmap_npages) {
+		printk("%s: Invalid gfn: %#llx\n", __func__, gfn);
+		kvm_mips_dump_host_tlbs();
+		kvm_arch_vcpu_dump_regs(vcpu);
+		return -1;
+	}
+	pfn = kvm->arch.guest_pmap[gfn];
+	pa = (pfn << PAGE_SHIFT) | offset;
+
+	printk("%s: va: %#lx, unmapped: %#x\n", __func__, va, CKSEG0ADDR(pa));
+
+	mips32_SyncICache(CKSEG0ADDR(pa), 32);
+	return 0;
+}
+
+#define MIPS_CACHE_OP_INDEX_INV         0x0
+#define MIPS_CACHE_OP_INDEX_LD_TAG      0x1
+#define MIPS_CACHE_OP_INDEX_ST_TAG      0x2
+#define MIPS_CACHE_OP_IMP               0x3
+#define MIPS_CACHE_OP_HIT_INV           0x4
+#define MIPS_CACHE_OP_FILL_WB_INV       0x5
+#define MIPS_CACHE_OP_HIT_HB            0x6
+#define MIPS_CACHE_OP_FETCH_LOCK        0x7
+
+#define MIPS_CACHE_ICACHE               0x0
+#define MIPS_CACHE_DCACHE               0x1
+#define MIPS_CACHE_SEC                  0x3
+
+enum emulation_result
+kvm_mips_emulate_cache(uint32_t inst, uint32_t *opc, uint32_t cause,
+		       struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	extern void (*r4k_blast_dcache) (void);
+	extern void (*r4k_blast_icache) (void);
+	enum emulation_result er = EMULATE_DONE;
+	int32_t offset, cache, op_inst, op, base;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	unsigned long va;
+	unsigned long curr_pc;
+
+	/*
+	 * Update PC and hold onto current PC in case there is
+	 * an error and we want to rollback the PC
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, cause);
+	if (er == EMULATE_FAIL)
+		return er;
+
+	base = (inst >> 21) & 0x1f;
+	op_inst = (inst >> 16) & 0x1f;
+	offset = inst & 0xffff;
+	cache = (inst >> 16) & 0x3;
+	op = (inst >> 18) & 0x7;
+
+	va = arch->gprs[base] + offset;
+
+	kvm_debug("CACHE (cache: %#x, op: %#x, base[%d]: %#lx, offset: %#x\n",
+		  cache, op, base, arch->gprs[base], offset);
+
+	/* Treat INDEX_INV as a nop, basically issued by Linux on startup to invalidate
+	 * the caches entirely by stepping through all the ways/indexes
+	 */
+	if (op == MIPS_CACHE_OP_INDEX_INV) {
+		kvm_debug
+		    ("@ %#lx/%#lx CACHE (cache: %#x, op: %#x, base[%d]: %#lx, offset: %#x\n",
+		     vcpu->arch.pc, vcpu->arch.gprs[31], cache, op, base,
+		     arch->gprs[base], offset);
+
+		if (cache == MIPS_CACHE_DCACHE)
+			r4k_blast_dcache();
+		else if (cache == MIPS_CACHE_ICACHE)
+			r4k_blast_icache();
+		else {
+			printk("%s: unsupported CACHE INDEX operation\n",
+			       __func__);
+			return EMULATE_FAIL;
+		}
+
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+		kvm_mips_trans_cache_index(inst, opc, vcpu);
+#endif
+		goto done;
+	}
+
+	preempt_disable();
+	if (KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG0) {
+
+		if (kvm_mips_host_tlb_lookup(vcpu, va) < 0) {
+			kvm_mips_handle_kseg0_tlb_fault(va, vcpu);
+		}
+	} else if ((KVM_GUEST_KSEGX(va) < KVM_GUEST_KSEG0) ||
+		   KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG23) {
+		int index;
+
+		/* If an entry already exists then skip */
+		if (kvm_mips_host_tlb_lookup(vcpu, va) >= 0) {
+			goto skip_fault;
+		}
+
+		/* If address not in the guest TLB, then give the guest a fault, the
+		 * resulting handler will do the right thing
+		 */
+		index = kvm_mips_guest_tlb_lookup(vcpu, (va & VPN2_MASK) |
+						  (kvm_read_c0_guest_entryhi
+						   (cop0) & ASID_MASK));
+
+		if (index < 0) {
+			vcpu->arch.host_cp0_entryhi = (va & VPN2_MASK);
+			vcpu->arch.host_cp0_badvaddr = va;
+			er = kvm_mips_emulate_tlbmiss_ld(cause, NULL, run,
+							 vcpu);
+			preempt_enable();
+			goto dont_update_pc;
+		} else {
+			struct kvm_mips_tlb *tlb = &vcpu->arch.guest_tlb[index];
+			/* Check if the entry is valid, if not then setup a TLB invalid exception to the guest */
+			if (!TLB_IS_VALID(*tlb, va)) {
+				er = kvm_mips_emulate_tlbinv_ld(cause, NULL,
+								run, vcpu);
+				preempt_enable();
+				goto dont_update_pc;
+			} else {
+				/* We fault an entry from the guest tlb to the shadow host TLB */
+				kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb,
+								     NULL,
+								     NULL);
+			}
+		}
+	} else {
+		printk
+		    ("INVALID CACHE INDEX/ADDRESS (cache: %#x, op: %#x, base[%d]: %#lx, offset: %#x\n",
+		     cache, op, base, arch->gprs[base], offset);
+		er = EMULATE_FAIL;
+		preempt_enable();
+		goto dont_update_pc;
+
+	}
+
+skip_fault:
+	/* XXXKYMA: Only a subset of cache ops are supported, used by Linux */
+	if (cache == MIPS_CACHE_DCACHE
+	    && (op == MIPS_CACHE_OP_FILL_WB_INV
+		|| op == MIPS_CACHE_OP_HIT_INV)) {
+		flush_dcache_line(va);
+
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+		/* Replace the CACHE instruction, with a SYNCI, not the same, but avoids a trap */
+		kvm_mips_trans_cache_va(inst, opc, vcpu);
+#endif
+	} else if (op == MIPS_CACHE_OP_HIT_INV && cache == MIPS_CACHE_ICACHE) {
+		flush_dcache_line(va);
+		flush_icache_line(va);
+
+#ifdef CONFIG_KVM_MIPS_DYN_TRANS
+		/* Replace the CACHE instruction, with a SYNCI */
+		kvm_mips_trans_cache_va(inst, opc, vcpu);
+#endif
+	} else {
+		printk
+		    ("NO-OP CACHE (cache: %#x, op: %#x, base[%d]: %#lx, offset: %#x\n",
+		     cache, op, base, arch->gprs[base], offset);
+		er = EMULATE_FAIL;
+		preempt_enable();
+		goto dont_update_pc;
+	}
+
+	preempt_enable();
+
+      dont_update_pc:
+	/*
+	 * Rollback PC
+	 */
+	vcpu->arch.pc = curr_pc;
+      done:
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_inst(unsigned long cause, uint32_t *opc,
+		      struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+	uint32_t inst;
+
+	/*
+	 *  Fetch the instruction.
+	 */
+	if (cause & CAUSEF_BD) {
+		opc += 1;
+	}
+
+	inst = kvm_get_inst(opc, vcpu);
+
+	switch (((union mips_instruction)inst).r_format.opcode) {
+	case cop0_op:
+		er = kvm_mips_emulate_CP0(inst, opc, cause, run, vcpu);
+		break;
+	case sb_op:
+	case sh_op:
+	case sw_op:
+		er = kvm_mips_emulate_store(inst, cause, run, vcpu);
+		break;
+	case lb_op:
+	case lbu_op:
+	case lhu_op:
+	case lh_op:
+	case lw_op:
+		er = kvm_mips_emulate_load(inst, cause, run, vcpu);
+		break;
+
+	case cache_op:
+		++vcpu->stat.cache_exits;
+		trace_kvm_exit(vcpu, CACHE_EXITS);
+		er = kvm_mips_emulate_cache(inst, opc, cause, run, vcpu);
+		break;
+
+	default:
+		printk("Instruction emulation not supported (%p/%#x)\n", opc,
+		       inst);
+		kvm_arch_vcpu_dump_regs(vcpu);
+		er = EMULATE_FAIL;
+		break;
+	}
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_syscall(unsigned long cause, uint32_t *opc,
+			 struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("Delivering SYSCALL @ pc %#lx\n", arch->pc);
+
+		kvm_change_c0_guest_cause(cop0, (0xff),
+					  (T_SYSCALL << CAUSEB_EXCCODE));
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+	} else {
+		printk("Trying to deliver SYSCALL when EXL is already set\n");
+		er = EMULATE_FAIL;
+	}
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_tlbmiss_ld(unsigned long cause, uint32_t *opc,
+			    struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long entryhi = (vcpu->arch.  host_cp0_badvaddr & VPN2_MASK) |
+				(kvm_read_c0_guest_entryhi(cop0) & ASID_MASK);
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("[EXL == 0] delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+
+		/* set pc to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x0;
+
+	} else {
+		kvm_debug("[EXL == 1] delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	}
+
+	kvm_change_c0_guest_cause(cop0, (0xff),
+				  (T_TLB_LD_MISS << CAUSEB_EXCCODE));
+
+	/* setup badvaddr, context and entryhi registers for the guest */
+	kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+	/* XXXKYMA: is the context register used by linux??? */
+	kvm_write_c0_guest_entryhi(cop0, entryhi);
+	/* Blow away the shadow host TLBs */
+	kvm_mips_flush_host_tlb(1);
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_tlbinv_ld(unsigned long cause, uint32_t *opc,
+			   struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long entryhi =
+		(vcpu->arch.host_cp0_badvaddr & VPN2_MASK) |
+		(kvm_read_c0_guest_entryhi(cop0) & ASID_MASK);
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("[EXL == 0] delivering TLB INV @ pc %#lx\n",
+			  arch->pc);
+
+		/* set pc to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+	} else {
+		kvm_debug("[EXL == 1] delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	}
+
+	kvm_change_c0_guest_cause(cop0, (0xff),
+				  (T_TLB_LD_MISS << CAUSEB_EXCCODE));
+
+	/* setup badvaddr, context and entryhi registers for the guest */
+	kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+	/* XXXKYMA: is the context register used by linux??? */
+	kvm_write_c0_guest_entryhi(cop0, entryhi);
+	/* Blow away the shadow host TLBs */
+	kvm_mips_flush_host_tlb(1);
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_tlbmiss_st(unsigned long cause, uint32_t *opc,
+			    struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long entryhi = (vcpu->arch.host_cp0_badvaddr & VPN2_MASK) |
+				(kvm_read_c0_guest_entryhi(cop0) & ASID_MASK);
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("[EXL == 0] Delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x0;
+	} else {
+		kvm_debug("[EXL == 1] Delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	}
+
+	kvm_change_c0_guest_cause(cop0, (0xff),
+				  (T_TLB_ST_MISS << CAUSEB_EXCCODE));
+
+	/* setup badvaddr, context and entryhi registers for the guest */
+	kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+	/* XXXKYMA: is the context register used by linux??? */
+	kvm_write_c0_guest_entryhi(cop0, entryhi);
+	/* Blow away the shadow host TLBs */
+	kvm_mips_flush_host_tlb(1);
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_tlbinv_st(unsigned long cause, uint32_t *opc,
+			   struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long entryhi = (vcpu->arch.host_cp0_badvaddr & VPN2_MASK) |
+		(kvm_read_c0_guest_entryhi(cop0) & ASID_MASK);
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("[EXL == 0] Delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	} else {
+		kvm_debug("[EXL == 1] Delivering TLB MISS @ pc %#lx\n",
+			  arch->pc);
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	}
+
+	kvm_change_c0_guest_cause(cop0, (0xff),
+				  (T_TLB_ST_MISS << CAUSEB_EXCCODE));
+
+	/* setup badvaddr, context and entryhi registers for the guest */
+	kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+	/* XXXKYMA: is the context register used by linux??? */
+	kvm_write_c0_guest_entryhi(cop0, entryhi);
+	/* Blow away the shadow host TLBs */
+	kvm_mips_flush_host_tlb(1);
+
+	return er;
+}
+
+/* TLBMOD: store into address matching TLB with Dirty bit off */
+enum emulation_result
+kvm_mips_handle_tlbmod(unsigned long cause, uint32_t *opc,
+		       struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+
+#ifdef DEBUG
+	/*
+	 * If address not in the guest TLB, then we are in trouble
+	 */
+	index = kvm_mips_guest_tlb_lookup(vcpu, entryhi);
+	if (index < 0) {
+		/* XXXKYMA Invalidate and retry */
+		kvm_mips_host_tlb_inv(vcpu, vcpu->arch.host_cp0_badvaddr);
+		kvm_err("%s: host got TLBMOD for %#lx but entry not present in Guest TLB\n",
+		     __func__, entryhi);
+		kvm_mips_dump_guest_tlbs(vcpu);
+		kvm_mips_dump_host_tlbs();
+		return EMULATE_FAIL;
+	}
+#endif
+
+	er = kvm_mips_emulate_tlbmod(cause, opc, run, vcpu);
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_tlbmod(unsigned long cause, uint32_t *opc,
+			struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	unsigned long entryhi = (vcpu->arch.host_cp0_badvaddr & VPN2_MASK) |
+				(kvm_read_c0_guest_entryhi(cop0) & ASID_MASK);
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("[EXL == 0] Delivering TLB MOD @ pc %#lx\n",
+			  arch->pc);
+
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	} else {
+		kvm_debug("[EXL == 1] Delivering TLB MOD @ pc %#lx\n",
+			  arch->pc);
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+	}
+
+	kvm_change_c0_guest_cause(cop0, (0xff), (T_TLB_MOD << CAUSEB_EXCCODE));
+
+	/* setup badvaddr, context and entryhi registers for the guest */
+	kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+	/* XXXKYMA: is the context register used by linux??? */
+	kvm_write_c0_guest_entryhi(cop0, entryhi);
+	/* Blow away the shadow host TLBs */
+	kvm_mips_flush_host_tlb(1);
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_fpu_exc(unsigned long cause, uint32_t *opc,
+			 struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+	}
+
+	arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+	kvm_change_c0_guest_cause(cop0, (0xff),
+				  (T_COP_UNUSABLE << CAUSEB_EXCCODE));
+	kvm_change_c0_guest_cause(cop0, (CAUSEF_CE), (0x1 << CAUSEB_CE));
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_ri_exc(unsigned long cause, uint32_t *opc,
+			struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("Delivering RI @ pc %#lx\n", arch->pc);
+
+		kvm_change_c0_guest_cause(cop0, (0xff),
+					  (T_RES_INST << CAUSEB_EXCCODE));
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+	} else {
+		kvm_err("Trying to deliver RI when EXL is already set\n");
+		er = EMULATE_FAIL;
+	}
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_emulate_bp_exc(unsigned long cause, uint32_t *opc,
+			struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_debug("Delivering BP @ pc %#lx\n", arch->pc);
+
+		kvm_change_c0_guest_cause(cop0, (0xff),
+					  (T_BREAK << CAUSEB_EXCCODE));
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+
+	} else {
+		printk("Trying to deliver BP when EXL is already set\n");
+		er = EMULATE_FAIL;
+	}
+
+	return er;
+}
+
+/*
+ * ll/sc, rdhwr, sync emulation
+ */
+
+#define OPCODE 0xfc000000
+#define BASE   0x03e00000
+#define RT     0x001f0000
+#define OFFSET 0x0000ffff
+#define LL     0xc0000000
+#define SC     0xe0000000
+#define SPEC0  0x00000000
+#define SPEC3  0x7c000000
+#define RD     0x0000f800
+#define FUNC   0x0000003f
+#define SYNC   0x0000000f
+#define RDHWR  0x0000003b
+
+enum emulation_result
+kvm_mips_handle_ri(unsigned long cause, uint32_t *opc,
+		   struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long curr_pc;
+	uint32_t inst;
+
+	/*
+	 * Update PC and hold onto current PC in case there is
+	 * an error and we want to rollback the PC
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, cause);
+	if (er == EMULATE_FAIL)
+		return er;
+
+	/*
+	 *  Fetch the instruction.
+	 */
+	if (cause & CAUSEF_BD)
+		opc += 1;
+
+	inst = kvm_get_inst(opc, vcpu);
+
+	if (inst == KVM_INVALID_INST) {
+		printk("%s: Cannot get inst @ %p\n", __func__, opc);
+		return EMULATE_FAIL;
+	}
+
+	if ((inst & OPCODE) == SPEC3 && (inst & FUNC) == RDHWR) {
+		int rd = (inst & RD) >> 11;
+		int rt = (inst & RT) >> 16;
+		switch (rd) {
+		case 0:	/* CPU number */
+			arch->gprs[rt] = 0;
+			break;
+		case 1:	/* SYNCI length */
+			arch->gprs[rt] = min(current_cpu_data.dcache.linesz,
+					     current_cpu_data.icache.linesz);
+			break;
+		case 2:	/* Read count register */
+			printk("RDHWR: Cont register\n");
+			arch->gprs[rt] = kvm_read_c0_guest_count(cop0);
+			break;
+		case 3:	/* Count register resolution */
+			switch (current_cpu_data.cputype) {
+			case CPU_20KC:
+			case CPU_25KF:
+				arch->gprs[rt] = 1;
+				break;
+			default:
+				arch->gprs[rt] = 2;
+			}
+			break;
+		case 29:
+#if 1
+			arch->gprs[rt] = kvm_read_c0_guest_userlocal(cop0);
+#else
+			/* UserLocal not implemented */
+			er = kvm_mips_emulate_ri_exc(cause, opc, run, vcpu);
+#endif
+			break;
+
+		default:
+			printk("RDHWR not supported\n");
+			er = EMULATE_FAIL;
+			break;
+		}
+	} else {
+		printk("Emulate RI not supported @ %p: %#x\n", opc, inst);
+		er = EMULATE_FAIL;
+	}
+
+	/*
+	 * Rollback PC only if emulation was unsuccessful
+	 */
+	if (er == EMULATE_FAIL) {
+		vcpu->arch.pc = curr_pc;
+	}
+	return er;
+}
+
+enum emulation_result
+kvm_mips_complete_mmio_load(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	unsigned long *gpr = &vcpu->arch.gprs[vcpu->arch.io_gpr];
+	enum emulation_result er = EMULATE_DONE;
+	unsigned long curr_pc;
+
+	if (run->mmio.len > sizeof(*gpr)) {
+		printk("Bad MMIO length: %d", run->mmio.len);
+		er = EMULATE_FAIL;
+		goto done;
+	}
+
+	/*
+	 * Update PC and hold onto current PC in case there is
+	 * an error and we want to rollback the PC
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, vcpu->arch.pending_load_cause);
+	if (er == EMULATE_FAIL)
+		return er;
+
+	switch (run->mmio.len) {
+	case 4:
+		*gpr = *(int32_t *) run->mmio.data;
+		break;
+
+	case 2:
+		if (vcpu->mmio_needed == 2)
+			*gpr = *(int16_t *) run->mmio.data;
+		else
+			*gpr = *(int16_t *) run->mmio.data;
+
+		break;
+	case 1:
+		if (vcpu->mmio_needed == 2)
+			*gpr = *(int8_t *) run->mmio.data;
+		else
+			*gpr = *(u8 *) run->mmio.data;
+		break;
+	}
+
+	if (vcpu->arch.pending_load_cause & CAUSEF_BD)
+		kvm_debug
+		    ("[%#lx] Completing %d byte BD Load to gpr %d (0x%08lx) type %d\n",
+		     vcpu->arch.pc, run->mmio.len, vcpu->arch.io_gpr, *gpr,
+		     vcpu->mmio_needed);
+
+done:
+	return er;
+}
+
+static enum emulation_result
+kvm_mips_emulate_exc(unsigned long cause, uint32_t *opc,
+		     struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	uint32_t exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
+	struct mips_coproc *cop0 = vcpu->arch.cop0;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	enum emulation_result er = EMULATE_DONE;
+
+	if ((kvm_read_c0_guest_status(cop0) & ST0_EXL) == 0) {
+		/* save old pc */
+		kvm_write_c0_guest_epc(cop0, arch->pc);
+		kvm_set_c0_guest_status(cop0, ST0_EXL);
+
+		if (cause & CAUSEF_BD)
+			kvm_set_c0_guest_cause(cop0, CAUSEF_BD);
+		else
+			kvm_clear_c0_guest_cause(cop0, CAUSEF_BD);
+
+		kvm_change_c0_guest_cause(cop0, (0xff),
+					  (exccode << CAUSEB_EXCCODE));
+
+		/* Set PC to the exception entry point */
+		arch->pc = KVM_GUEST_KSEG0 + 0x180;
+		kvm_write_c0_guest_badvaddr(cop0, vcpu->arch.host_cp0_badvaddr);
+
+		kvm_debug("Delivering EXC %d @ pc %#lx, badVaddr: %#lx\n",
+			  exccode, kvm_read_c0_guest_epc(cop0),
+			  kvm_read_c0_guest_badvaddr(cop0));
+	} else {
+		printk("Trying to deliver EXC when EXL is already set\n");
+		er = EMULATE_FAIL;
+	}
+
+	return er;
+}
+
+enum emulation_result
+kvm_mips_check_privilege(unsigned long cause, uint32_t *opc,
+			 struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+	uint32_t exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
+	unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;
+
+	int usermode = !KVM_GUEST_KERNEL_MODE(vcpu);
+
+	if (usermode) {
+		switch (exccode) {
+		case T_INT:
+		case T_SYSCALL:
+		case T_BREAK:
+		case T_RES_INST:
+			break;
+
+		case T_COP_UNUSABLE:
+			if (((cause & CAUSEF_CE) >> CAUSEB_CE) == 0)
+				er = EMULATE_PRIV_FAIL;
+			break;
+
+		case T_TLB_MOD:
+			break;
+
+		case T_TLB_LD_MISS:
+			/* We we are accessing Guest kernel space, then send an address error exception to the guest */
+			if (badvaddr >= (unsigned long) KVM_GUEST_KSEG0) {
+				printk("%s: LD MISS @ %#lx\n", __func__,
+				       badvaddr);
+				cause &= ~0xff;
+				cause |= (T_ADDR_ERR_LD << CAUSEB_EXCCODE);
+				er = EMULATE_PRIV_FAIL;
+			}
+			break;
+
+		case T_TLB_ST_MISS:
+			/* We we are accessing Guest kernel space, then send an address error exception to the guest */
+			if (badvaddr >= (unsigned long) KVM_GUEST_KSEG0) {
+				printk("%s: ST MISS @ %#lx\n", __func__,
+				       badvaddr);
+				cause &= ~0xff;
+				cause |= (T_ADDR_ERR_ST << CAUSEB_EXCCODE);
+				er = EMULATE_PRIV_FAIL;
+			}
+			break;
+
+		case T_ADDR_ERR_ST:
+			printk("%s: address error ST @ %#lx\n", __func__,
+			       badvaddr);
+			if ((badvaddr & PAGE_MASK) == KVM_GUEST_COMMPAGE_ADDR) {
+				cause &= ~0xff;
+				cause |= (T_TLB_ST_MISS << CAUSEB_EXCCODE);
+			}
+			er = EMULATE_PRIV_FAIL;
+			break;
+		case T_ADDR_ERR_LD:
+			printk("%s: address error LD @ %#lx\n", __func__,
+			       badvaddr);
+			if ((badvaddr & PAGE_MASK) == KVM_GUEST_COMMPAGE_ADDR) {
+				cause &= ~0xff;
+				cause |= (T_TLB_LD_MISS << CAUSEB_EXCCODE);
+			}
+			er = EMULATE_PRIV_FAIL;
+			break;
+		default:
+			er = EMULATE_PRIV_FAIL;
+			break;
+		}
+	}
+
+	if (er == EMULATE_PRIV_FAIL) {
+		kvm_mips_emulate_exc(cause, opc, run, vcpu);
+	}
+	return er;
+}
+
+/* User Address (UA) fault, this could happen if
+ * (1) TLB entry not present/valid in both Guest and shadow host TLBs, in this
+ *     case we pass on the fault to the guest kernel and let it handle it.
+ * (2) TLB entry is present in the Guest TLB but not in the shadow, in this
+ *     case we inject the TLB from the Guest TLB into the shadow host TLB
+ */
+enum emulation_result
+kvm_mips_handle_tlbmiss(unsigned long cause, uint32_t *opc,
+			struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	enum emulation_result er = EMULATE_DONE;
+	uint32_t exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
+	unsigned long va = vcpu->arch.host_cp0_badvaddr;
+	int index;
+
+	kvm_debug("kvm_mips_handle_tlbmiss: badvaddr: %#lx, entryhi: %#lx\n",
+		  vcpu->arch.host_cp0_badvaddr, vcpu->arch.host_cp0_entryhi);
+
+	/* KVM would not have got the exception if this entry was valid in the shadow host TLB
+	 * Check the Guest TLB, if the entry is not there then send the guest an
+	 * exception. The guest exc handler should then inject an entry into the
+	 * guest TLB
+	 */
+	index = kvm_mips_guest_tlb_lookup(vcpu,
+					  (va & VPN2_MASK) |
+					  (kvm_read_c0_guest_entryhi
+					   (vcpu->arch.cop0) & ASID_MASK));
+	if (index < 0) {
+		if (exccode == T_TLB_LD_MISS) {
+			er = kvm_mips_emulate_tlbmiss_ld(cause, opc, run, vcpu);
+		} else if (exccode == T_TLB_ST_MISS) {
+			er = kvm_mips_emulate_tlbmiss_st(cause, opc, run, vcpu);
+		} else {
+			printk("%s: invalid exc code: %d\n", __func__, exccode);
+			er = EMULATE_FAIL;
+		}
+	} else {
+		struct kvm_mips_tlb *tlb = &vcpu->arch.guest_tlb[index];
+
+		/* Check if the entry is valid, if not then setup a TLB invalid exception to the guest */
+		if (!TLB_IS_VALID(*tlb, va)) {
+			if (exccode == T_TLB_LD_MISS) {
+				er = kvm_mips_emulate_tlbinv_ld(cause, opc, run,
+								vcpu);
+			} else if (exccode == T_TLB_ST_MISS) {
+				er = kvm_mips_emulate_tlbinv_st(cause, opc, run,
+								vcpu);
+			} else {
+				printk("%s: invalid exc code: %d\n", __func__,
+				       exccode);
+				er = EMULATE_FAIL;
+			}
+		} else {
+#ifdef DEBUG
+			kvm_debug
+			    ("Injecting hi: %#lx, lo0: %#lx, lo1: %#lx into shadow host TLB\n",
+			     tlb->tlb_hi, tlb->tlb_lo0, tlb->tlb_lo1);
+#endif
+			/* OK we have a Guest TLB entry, now inject it into the shadow host TLB */
+			kvm_mips_handle_mapped_seg_tlb_fault(vcpu, tlb, NULL,
+							     NULL);
+		}
+	}
+
+	return er;
+}
diff --git a/arch/mips/kvm/kvm_mips_opcode.h b/arch/mips/kvm/kvm_mips_opcode.h
new file mode 100644
index 000000000000..86d3b4cc348b
--- /dev/null
+++ b/arch/mips/kvm/kvm_mips_opcode.h
@@ -0,0 +1,24 @@
+/*
+* This file is subject to the terms and conditions of the GNU General Public
+* License.  See the file "COPYING" in the main directory of this archive
+* for more details.
+*
+* Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
+* Authors: Sanjay Lal <sanjayl@kymasys.com>
+*/
+
+/*
+ * Define opcode values not defined in <asm/isnt.h>
+ */
+
+#ifndef __KVM_MIPS_OPCODE_H__
+#define __KVM_MIPS_OPCODE_H__
+
+/* COP0 Ops */
+#define     mfmcz_op         0x0b	/*  01011  */
+#define     wrpgpr_op        0x0e	/*  01110  */
+
+/*  COP0 opcodes (only if COP0 and CO=1):  */
+#define     wait_op               0x20	/*  100000  */
+
+#endif /* __KVM_MIPS_OPCODE_H__ */