Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 1650 insertions, 0 deletions

diff --git a/arch/mips/kvm/emulate.c b/arch/mips/kvm/emulate.c
new file mode 100644
index 000000000..0feec5222
--- /dev/null
+++ b/arch/mips/kvm/emulate.c
@@ -0,0 +1,1650 @@
+/*
+ * 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/ktime.h>
+#include <linux/kvm_host.h>
+#include <linux/vmalloc.h>
+#include <linux/fs.h>
+#include <linux/memblock.h>
+#include <linux/random.h>
+#include <asm/page.h>
+#include <asm/cacheflush.h>
+#include <asm/cacheops.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 "interrupt.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.
+ */
+static int kvm_compute_return_epc(struct kvm_vcpu *vcpu, unsigned long instpc,
+				  unsigned long *out)
+{
+	unsigned int dspcontrol;
+	union mips_instruction insn;
+	struct kvm_vcpu_arch *arch = &vcpu->arch;
+	long epc = instpc;
+	long nextpc;
+	int err;
+
+	if (epc & 3) {
+		kvm_err("%s: unaligned epc\n", __func__);
+		return -EINVAL;
+	}
+
+	/* Read the instruction */
+	err = kvm_get_badinstrp((u32 *)epc, vcpu, &insn.word);
+	if (err)
+		return err;
+
+	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;
+			fallthrough;
+		case jr_op:
+			nextpc = arch->gprs[insn.r_format.rs];
+			break;
+		default:
+			return -EINVAL;
+		}
+		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) {
+				kvm_err("%s: DSP branch but not DSP ASE\n",
+					__func__);
+				return -EINVAL;
+			}
+
+			dspcontrol = rddsp(0x01);
+
+			if (dspcontrol >= 32)
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			else
+				epc += 8;
+			nextpc = epc;
+			break;
+		default:
+			return -EINVAL;
+		}
+		break;
+
+		/* These are unconditional and in j_format. */
+	case jal_op:
+		arch->gprs[31] = instpc + 8;
+		fallthrough;
+	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:	/* POP06 */
+#ifndef CONFIG_CPU_MIPSR6
+	case blezl_op:	/* removed in R6 */
+#endif
+		if (insn.i_format.rt != 0)
+			goto compact_branch;
+		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:	/* POP07 */
+#ifndef CONFIG_CPU_MIPSR6
+	case bgtzl_op:	/* removed in R6 */
+#endif
+		if (insn.i_format.rt != 0)
+			goto compact_branch;
+		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:
+		kvm_err("%s: unsupported cop1_op\n", __func__);
+		return -EINVAL;
+
+#ifdef CONFIG_CPU_MIPSR6
+	/* R6 added the following compact branches with forbidden slots */
+	case blezl_op:	/* POP26 */
+	case bgtzl_op:	/* POP27 */
+		/* only rt == 0 isn't compact branch */
+		if (insn.i_format.rt != 0)
+			goto compact_branch;
+		return -EINVAL;
+	case pop10_op:
+	case pop30_op:
+		/* only rs == rt == 0 is reserved, rest are compact branches */
+		if (insn.i_format.rs != 0 || insn.i_format.rt != 0)
+			goto compact_branch;
+		return -EINVAL;
+	case pop66_op:
+	case pop76_op:
+		/* only rs == 0 isn't compact branch */
+		if (insn.i_format.rs != 0)
+			goto compact_branch;
+		return -EINVAL;
+compact_branch:
+		/*
+		 * If we've hit an exception on the forbidden slot, then
+		 * the branch must not have been taken.
+		 */
+		epc += 8;
+		nextpc = epc;
+		break;
+#else
+compact_branch:
+		/* Fall through - Compact branches not supported before R6 */
+#endif
+	default:
+		return -EINVAL;
+	}
+
+	*out = nextpc;
+	return 0;
+}
+
+enum emulation_result update_pc(struct kvm_vcpu *vcpu, u32 cause)
+{
+	int err;
+
+	if (cause & CAUSEF_BD) {
+		err = kvm_compute_return_epc(vcpu, vcpu->arch.pc,
+					     &vcpu->arch.pc);
+		if (err)
+			return EMULATE_FAIL;
+	} else {
+		vcpu->arch.pc += 4;
+	}
+
+	kvm_debug("update_pc(): New PC: %#lx\n", vcpu->arch.pc);
+
+	return EMULATE_DONE;
+}
+
+/**
+ * kvm_get_badinstr() - Get bad instruction encoding.
+ * @opc:	Guest pointer to faulting instruction.
+ * @vcpu:	KVM VCPU information.
+ *
+ * Gets the instruction encoding of the faulting instruction, using the saved
+ * BadInstr register value if it exists, otherwise falling back to reading guest
+ * memory at @opc.
+ *
+ * Returns:	The instruction encoding of the faulting instruction.
+ */
+int kvm_get_badinstr(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
+{
+	if (cpu_has_badinstr) {
+		*out = vcpu->arch.host_cp0_badinstr;
+		return 0;
+	} else {
+		WARN_ONCE(1, "CPU doesn't have BadInstr register\n");
+		return -EINVAL;
+	}
+}
+
+/**
+ * kvm_get_badinstrp() - Get bad prior instruction encoding.
+ * @opc:	Guest pointer to prior faulting instruction.
+ * @vcpu:	KVM VCPU information.
+ *
+ * Gets the instruction encoding of the prior faulting instruction (the branch
+ * containing the delay slot which faulted), using the saved BadInstrP register
+ * value if it exists, otherwise falling back to reading guest memory at @opc.
+ *
+ * Returns:	The instruction encoding of the prior faulting instruction.
+ */
+int kvm_get_badinstrp(u32 *opc, struct kvm_vcpu *vcpu, u32 *out)
+{
+	if (cpu_has_badinstrp) {
+		*out = vcpu->arch.host_cp0_badinstrp;
+		return 0;
+	} else {
+		WARN_ONCE(1, "CPU doesn't have BadInstrp register\n");
+		return -EINVAL;
+	}
+}
+
+/**
+ * kvm_mips_count_disabled() - Find whether the CP0_Count timer is disabled.
+ * @vcpu:	Virtual CPU.
+ *
+ * Returns:	1 if the CP0_Count timer is disabled by either the guest
+ *		CP0_Cause.DC bit or the count_ctl.DC bit.
+ *		0 otherwise (in which case CP0_Count timer is running).
+ */
+int kvm_mips_count_disabled(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+
+	return	(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) ||
+		(kvm_read_c0_guest_cause(cop0) & CAUSEF_DC);
+}
+
+/**
+ * kvm_mips_ktime_to_count() - Scale ktime_t to a 32-bit count.
+ *
+ * Caches the dynamic nanosecond bias in vcpu->arch.count_dyn_bias.
+ *
+ * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running).
+ */
+static u32 kvm_mips_ktime_to_count(struct kvm_vcpu *vcpu, ktime_t now)
+{
+	s64 now_ns, periods;
+	u64 delta;
+
+	now_ns = ktime_to_ns(now);
+	delta = now_ns + vcpu->arch.count_dyn_bias;
+
+	if (delta >= vcpu->arch.count_period) {
+		/* If delta is out of safe range the bias needs adjusting */
+		periods = div64_s64(now_ns, vcpu->arch.count_period);
+		vcpu->arch.count_dyn_bias = -periods * vcpu->arch.count_period;
+		/* Recalculate delta with new bias */
+		delta = now_ns + vcpu->arch.count_dyn_bias;
+	}
+
+	/*
+	 * We've ensured that:
+	 *   delta < count_period
+	 *
+	 * Therefore the intermediate delta*count_hz will never overflow since
+	 * at the boundary condition:
+	 *   delta = count_period
+	 *   delta = NSEC_PER_SEC * 2^32 / count_hz
+	 *   delta * count_hz = NSEC_PER_SEC * 2^32
+	 */
+	return div_u64(delta * vcpu->arch.count_hz, NSEC_PER_SEC);
+}
+
+/**
+ * kvm_mips_count_time() - Get effective current time.
+ * @vcpu:	Virtual CPU.
+ *
+ * Get effective monotonic ktime. This is usually a straightforward ktime_get(),
+ * except when the master disable bit is set in count_ctl, in which case it is
+ * count_resume, i.e. the time that the count was disabled.
+ *
+ * Returns:	Effective monotonic ktime for CP0_Count.
+ */
+static inline ktime_t kvm_mips_count_time(struct kvm_vcpu *vcpu)
+{
+	if (unlikely(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC))
+		return vcpu->arch.count_resume;
+
+	return ktime_get();
+}
+
+/**
+ * kvm_mips_read_count_running() - Read the current count value as if running.
+ * @vcpu:	Virtual CPU.
+ * @now:	Kernel time to read CP0_Count at.
+ *
+ * Returns the current guest CP0_Count register at time @now and handles if the
+ * timer interrupt is pending and hasn't been handled yet.
+ *
+ * Returns:	The current value of the guest CP0_Count register.
+ */
+static u32 kvm_mips_read_count_running(struct kvm_vcpu *vcpu, ktime_t now)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	ktime_t expires, threshold;
+	u32 count, compare;
+	int running;
+
+	/* Calculate the biased and scaled guest CP0_Count */
+	count = vcpu->arch.count_bias + kvm_mips_ktime_to_count(vcpu, now);
+	compare = kvm_read_c0_guest_compare(cop0);
+
+	/*
+	 * Find whether CP0_Count has reached the closest timer interrupt. If
+	 * not, we shouldn't inject it.
+	 */
+	if ((s32)(count - compare) < 0)
+		return count;
+
+	/*
+	 * The CP0_Count we're going to return has already reached the closest
+	 * timer interrupt. Quickly check if it really is a new interrupt by
+	 * looking at whether the interval until the hrtimer expiry time is
+	 * less than 1/4 of the timer period.
+	 */
+	expires = hrtimer_get_expires(&vcpu->arch.comparecount_timer);
+	threshold = ktime_add_ns(now, vcpu->arch.count_period / 4);
+	if (ktime_before(expires, threshold)) {
+		/*
+		 * Cancel it while we handle it so there's no chance of
+		 * interference with the timeout handler.
+		 */
+		running = hrtimer_cancel(&vcpu->arch.comparecount_timer);
+
+		/* Nothing should be waiting on the timeout */
+		kvm_mips_callbacks->queue_timer_int(vcpu);
+
+		/*
+		 * Restart the timer if it was running based on the expiry time
+		 * we read, so that we don't push it back 2 periods.
+		 */
+		if (running) {
+			expires = ktime_add_ns(expires,
+					       vcpu->arch.count_period);
+			hrtimer_start(&vcpu->arch.comparecount_timer, expires,
+				      HRTIMER_MODE_ABS);
+		}
+	}
+
+	return count;
+}
+
+/**
+ * kvm_mips_read_count() - Read the current count value.
+ * @vcpu:	Virtual CPU.
+ *
+ * Read the current guest CP0_Count value, taking into account whether the timer
+ * is stopped.
+ *
+ * Returns:	The current guest CP0_Count value.
+ */
+u32 kvm_mips_read_count(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+
+	/* If count disabled just read static copy of count */
+	if (kvm_mips_count_disabled(vcpu))
+		return kvm_read_c0_guest_count(cop0);
+
+	return kvm_mips_read_count_running(vcpu, ktime_get());
+}
+
+/**
+ * kvm_mips_freeze_hrtimer() - Safely stop the hrtimer.
+ * @vcpu:	Virtual CPU.
+ * @count:	Output pointer for CP0_Count value at point of freeze.
+ *
+ * Freeze the hrtimer safely and return both the ktime and the CP0_Count value
+ * at the point it was frozen. It is guaranteed that any pending interrupts at
+ * the point it was frozen are handled, and none after that point.
+ *
+ * This is useful where the time/CP0_Count is needed in the calculation of the
+ * new parameters.
+ *
+ * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running).
+ *
+ * Returns:	The ktime at the point of freeze.
+ */
+ktime_t kvm_mips_freeze_hrtimer(struct kvm_vcpu *vcpu, u32 *count)
+{
+	ktime_t now;
+
+	/* stop hrtimer before finding time */
+	hrtimer_cancel(&vcpu->arch.comparecount_timer);
+	now = ktime_get();
+
+	/* find count at this point and handle pending hrtimer */
+	*count = kvm_mips_read_count_running(vcpu, now);
+
+	return now;
+}
+
+/**
+ * kvm_mips_resume_hrtimer() - Resume hrtimer, updating expiry.
+ * @vcpu:	Virtual CPU.
+ * @now:	ktime at point of resume.
+ * @count:	CP0_Count at point of resume.
+ *
+ * Resumes the timer and updates the timer expiry based on @now and @count.
+ * This can be used in conjunction with kvm_mips_freeze_timer() when timer
+ * parameters need to be changed.
+ *
+ * It is guaranteed that a timer interrupt immediately after resume will be
+ * handled, but not if CP_Compare is exactly at @count. That case is already
+ * handled by kvm_mips_freeze_timer().
+ *
+ * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is running).
+ */
+static void kvm_mips_resume_hrtimer(struct kvm_vcpu *vcpu,
+				    ktime_t now, u32 count)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	u32 compare;
+	u64 delta;
+	ktime_t expire;
+
+	/* Calculate timeout (wrap 0 to 2^32) */
+	compare = kvm_read_c0_guest_compare(cop0);
+	delta = (u64)(u32)(compare - count - 1) + 1;
+	delta = div_u64(delta * NSEC_PER_SEC, vcpu->arch.count_hz);
+	expire = ktime_add_ns(now, delta);
+
+	/* Update hrtimer to use new timeout */
+	hrtimer_cancel(&vcpu->arch.comparecount_timer);
+	hrtimer_start(&vcpu->arch.comparecount_timer, expire, HRTIMER_MODE_ABS);
+}
+
+/**
+ * kvm_mips_restore_hrtimer() - Restore hrtimer after a gap, updating expiry.
+ * @vcpu:	Virtual CPU.
+ * @before:	Time before Count was saved, lower bound of drift calculation.
+ * @count:	CP0_Count at point of restore.
+ * @min_drift:	Minimum amount of drift permitted before correction.
+ *		Must be <= 0.
+ *
+ * Restores the timer from a particular @count, accounting for drift. This can
+ * be used in conjunction with kvm_mips_freeze_timer() when a hardware timer is
+ * to be used for a period of time, but the exact ktime corresponding to the
+ * final Count that must be restored is not known.
+ *
+ * It is guaranteed that a timer interrupt immediately after restore will be
+ * handled, but not if CP0_Compare is exactly at @count. That case should
+ * already be handled when the hardware timer state is saved.
+ *
+ * Assumes !kvm_mips_count_disabled(@vcpu) (guest CP0_Count timer is not
+ * stopped).
+ *
+ * Returns:	Amount of correction to count_bias due to drift.
+ */
+int kvm_mips_restore_hrtimer(struct kvm_vcpu *vcpu, ktime_t before,
+			     u32 count, int min_drift)
+{
+	ktime_t now, count_time;
+	u32 now_count, before_count;
+	u64 delta;
+	int drift, ret = 0;
+
+	/* Calculate expected count at before */
+	before_count = vcpu->arch.count_bias +
+			kvm_mips_ktime_to_count(vcpu, before);
+
+	/*
+	 * Detect significantly negative drift, where count is lower than
+	 * expected. Some negative drift is expected when hardware counter is
+	 * set after kvm_mips_freeze_timer(), and it is harmless to allow the
+	 * time to jump forwards a little, within reason. If the drift is too
+	 * significant, adjust the bias to avoid a big Guest.CP0_Count jump.
+	 */
+	drift = count - before_count;
+	if (drift < min_drift) {
+		count_time = before;
+		vcpu->arch.count_bias += drift;
+		ret = drift;
+		goto resume;
+	}
+
+	/* Calculate expected count right now */
+	now = ktime_get();
+	now_count = vcpu->arch.count_bias + kvm_mips_ktime_to_count(vcpu, now);
+
+	/*
+	 * Detect positive drift, where count is higher than expected, and
+	 * adjust the bias to avoid guest time going backwards.
+	 */
+	drift = count - now_count;
+	if (drift > 0) {
+		count_time = now;
+		vcpu->arch.count_bias += drift;
+		ret = drift;
+		goto resume;
+	}
+
+	/* Subtract nanosecond delta to find ktime when count was read */
+	delta = (u64)(u32)(now_count - count);
+	delta = div_u64(delta * NSEC_PER_SEC, vcpu->arch.count_hz);
+	count_time = ktime_sub_ns(now, delta);
+
+resume:
+	/* Resume using the calculated ktime */
+	kvm_mips_resume_hrtimer(vcpu, count_time, count);
+	return ret;
+}
+
+/**
+ * kvm_mips_write_count() - Modify the count and update timer.
+ * @vcpu:	Virtual CPU.
+ * @count:	Guest CP0_Count value to set.
+ *
+ * Sets the CP0_Count value and updates the timer accordingly.
+ */
+void kvm_mips_write_count(struct kvm_vcpu *vcpu, u32 count)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	ktime_t now;
+
+	/* Calculate bias */
+	now = kvm_mips_count_time(vcpu);
+	vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now);
+
+	if (kvm_mips_count_disabled(vcpu))
+		/* The timer's disabled, adjust the static count */
+		kvm_write_c0_guest_count(cop0, count);
+	else
+		/* Update timeout */
+		kvm_mips_resume_hrtimer(vcpu, now, count);
+}
+
+/**
+ * kvm_mips_init_count() - Initialise timer.
+ * @vcpu:	Virtual CPU.
+ * @count_hz:	Frequency of timer.
+ *
+ * Initialise the timer to the specified frequency, zero it, and set it going if
+ * it's enabled.
+ */
+void kvm_mips_init_count(struct kvm_vcpu *vcpu, unsigned long count_hz)
+{
+	vcpu->arch.count_hz = count_hz;
+	vcpu->arch.count_period = div_u64((u64)NSEC_PER_SEC << 32, count_hz);
+	vcpu->arch.count_dyn_bias = 0;
+
+	/* Starting at 0 */
+	kvm_mips_write_count(vcpu, 0);
+}
+
+/**
+ * kvm_mips_set_count_hz() - Update the frequency of the timer.
+ * @vcpu:	Virtual CPU.
+ * @count_hz:	Frequency of CP0_Count timer in Hz.
+ *
+ * Change the frequency of the CP0_Count timer. This is done atomically so that
+ * CP0_Count is continuous and no timer interrupt is lost.
+ *
+ * Returns:	-EINVAL if @count_hz is out of range.
+ *		0 on success.
+ */
+int kvm_mips_set_count_hz(struct kvm_vcpu *vcpu, s64 count_hz)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	int dc;
+	ktime_t now;
+	u32 count;
+
+	/* ensure the frequency is in a sensible range... */
+	if (count_hz <= 0 || count_hz > NSEC_PER_SEC)
+		return -EINVAL;
+	/* ... and has actually changed */
+	if (vcpu->arch.count_hz == count_hz)
+		return 0;
+
+	/* Safely freeze timer so we can keep it continuous */
+	dc = kvm_mips_count_disabled(vcpu);
+	if (dc) {
+		now = kvm_mips_count_time(vcpu);
+		count = kvm_read_c0_guest_count(cop0);
+	} else {
+		now = kvm_mips_freeze_hrtimer(vcpu, &count);
+	}
+
+	/* Update the frequency */
+	vcpu->arch.count_hz = count_hz;
+	vcpu->arch.count_period = div_u64((u64)NSEC_PER_SEC << 32, count_hz);
+	vcpu->arch.count_dyn_bias = 0;
+
+	/* Calculate adjusted bias so dynamic count is unchanged */
+	vcpu->arch.count_bias = count - kvm_mips_ktime_to_count(vcpu, now);
+
+	/* Update and resume hrtimer */
+	if (!dc)
+		kvm_mips_resume_hrtimer(vcpu, now, count);
+	return 0;
+}
+
+/**
+ * kvm_mips_write_compare() - Modify compare and update timer.
+ * @vcpu:	Virtual CPU.
+ * @compare:	New CP0_Compare value.
+ * @ack:	Whether to acknowledge timer interrupt.
+ *
+ * Update CP0_Compare to a new value and update the timeout.
+ * If @ack, atomically acknowledge any pending timer interrupt, otherwise ensure
+ * any pending timer interrupt is preserved.
+ */
+void kvm_mips_write_compare(struct kvm_vcpu *vcpu, u32 compare, bool ack)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	int dc;
+	u32 old_compare = kvm_read_c0_guest_compare(cop0);
+	s32 delta = compare - old_compare;
+	u32 cause;
+	ktime_t now = ktime_set(0, 0); /* silence bogus GCC warning */
+	u32 count;
+
+	/* if unchanged, must just be an ack */
+	if (old_compare == compare) {
+		if (!ack)
+			return;
+		kvm_mips_callbacks->dequeue_timer_int(vcpu);
+		kvm_write_c0_guest_compare(cop0, compare);
+		return;
+	}
+
+	/*
+	 * If guest CP0_Compare moves forward, CP0_GTOffset should be adjusted
+	 * too to prevent guest CP0_Count hitting guest CP0_Compare.
+	 *
+	 * The new GTOffset corresponds to the new value of CP0_Compare, and is
+	 * set prior to it being written into the guest context. We disable
+	 * preemption until the new value is written to prevent restore of a
+	 * GTOffset corresponding to the old CP0_Compare value.
+	 */
+	if (delta > 0) {
+		preempt_disable();
+		write_c0_gtoffset(compare - read_c0_count());
+		back_to_back_c0_hazard();
+	}
+
+	/* freeze_hrtimer() takes care of timer interrupts <= count */
+	dc = kvm_mips_count_disabled(vcpu);
+	if (!dc)
+		now = kvm_mips_freeze_hrtimer(vcpu, &count);
+
+	if (ack)
+		kvm_mips_callbacks->dequeue_timer_int(vcpu);
+	else
+		/*
+		 * With VZ, writing CP0_Compare acks (clears) CP0_Cause.TI, so
+		 * preserve guest CP0_Cause.TI if we don't want to ack it.
+		 */
+		cause = kvm_read_c0_guest_cause(cop0);
+
+	kvm_write_c0_guest_compare(cop0, compare);
+
+	if (delta > 0)
+		preempt_enable();
+
+	back_to_back_c0_hazard();
+
+	if (!ack && cause & CAUSEF_TI)
+		kvm_write_c0_guest_cause(cop0, cause);
+
+	/* resume_hrtimer() takes care of timer interrupts > count */
+	if (!dc)
+		kvm_mips_resume_hrtimer(vcpu, now, count);
+
+	/*
+	 * If guest CP0_Compare is moving backward, we delay CP0_GTOffset change
+	 * until after the new CP0_Compare is written, otherwise new guest
+	 * CP0_Count could hit new guest CP0_Compare.
+	 */
+	if (delta <= 0)
+		write_c0_gtoffset(compare - read_c0_count());
+}
+
+/**
+ * kvm_mips_count_disable() - Disable count.
+ * @vcpu:	Virtual CPU.
+ *
+ * Disable the CP0_Count timer. A timer interrupt on or before the final stop
+ * time will be handled but not after.
+ *
+ * Assumes CP0_Count was previously enabled but now Guest.CP0_Cause.DC or
+ * count_ctl.DC has been set (count disabled).
+ *
+ * Returns:	The time that the timer was stopped.
+ */
+static ktime_t kvm_mips_count_disable(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	u32 count;
+	ktime_t now;
+
+	/* Stop hrtimer */
+	hrtimer_cancel(&vcpu->arch.comparecount_timer);
+
+	/* Set the static count from the dynamic count, handling pending TI */
+	now = ktime_get();
+	count = kvm_mips_read_count_running(vcpu, now);
+	kvm_write_c0_guest_count(cop0, count);
+
+	return now;
+}
+
+/**
+ * kvm_mips_count_disable_cause() - Disable count using CP0_Cause.DC.
+ * @vcpu:	Virtual CPU.
+ *
+ * Disable the CP0_Count timer and set CP0_Cause.DC. A timer interrupt on or
+ * before the final stop time will be handled if the timer isn't disabled by
+ * count_ctl.DC, but not after.
+ *
+ * Assumes CP0_Cause.DC is clear (count enabled).
+ */
+void kvm_mips_count_disable_cause(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+
+	kvm_set_c0_guest_cause(cop0, CAUSEF_DC);
+	if (!(vcpu->arch.count_ctl & KVM_REG_MIPS_COUNT_CTL_DC))
+		kvm_mips_count_disable(vcpu);
+}
+
+/**
+ * kvm_mips_count_enable_cause() - Enable count using CP0_Cause.DC.
+ * @vcpu:	Virtual CPU.
+ *
+ * Enable the CP0_Count timer and clear CP0_Cause.DC. A timer interrupt after
+ * the start time will be handled if the timer isn't disabled by count_ctl.DC,
+ * potentially before even returning, so the caller should be careful with
+ * ordering of CP0_Cause modifications so as not to lose it.
+ *
+ * Assumes CP0_Cause.DC is set (count disabled).
+ */
+void kvm_mips_count_enable_cause(struct kvm_vcpu *vcpu)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	u32 count;
+
+	kvm_clear_c0_guest_cause(cop0, CAUSEF_DC);
+
+	/*
+	 * Set the dynamic count to match the static count.
+	 * This starts the hrtimer if count_ctl.DC allows it.
+	 * Otherwise it conveniently updates the biases.
+	 */
+	count = kvm_read_c0_guest_count(cop0);
+	kvm_mips_write_count(vcpu, count);
+}
+
+/**
+ * kvm_mips_set_count_ctl() - Update the count control KVM register.
+ * @vcpu:	Virtual CPU.
+ * @count_ctl:	Count control register new value.
+ *
+ * Set the count control KVM register. The timer is updated accordingly.
+ *
+ * Returns:	-EINVAL if reserved bits are set.
+ *		0 on success.
+ */
+int kvm_mips_set_count_ctl(struct kvm_vcpu *vcpu, s64 count_ctl)
+{
+	struct mips_coproc *cop0 = &vcpu->arch.cop0;
+	s64 changed = count_ctl ^ vcpu->arch.count_ctl;
+	s64 delta;
+	ktime_t expire, now;
+	u32 count, compare;
+
+	/* Only allow defined bits to be changed */
+	if (changed & ~(s64)(KVM_REG_MIPS_COUNT_CTL_DC))
+		return -EINVAL;
+
+	/* Apply new value */
+	vcpu->arch.count_ctl = count_ctl;
+
+	/* Master CP0_Count disable */
+	if (changed & KVM_REG_MIPS_COUNT_CTL_DC) {
+		/* Is CP0_Cause.DC already disabling CP0_Count? */
+		if (kvm_read_c0_guest_cause(cop0) & CAUSEF_DC) {
+			if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC)
+				/* Just record the current time */
+				vcpu->arch.count_resume = ktime_get();
+		} else if (count_ctl & KVM_REG_MIPS_COUNT_CTL_DC) {
+			/* disable timer and record current time */
+			vcpu->arch.count_resume = kvm_mips_count_disable(vcpu);
+		} else {
+			/*
+			 * Calculate timeout relative to static count at resume
+			 * time (wrap 0 to 2^32).
+			 */
+			count = kvm_read_c0_guest_count(cop0);
+			compare = kvm_read_c0_guest_compare(cop0);
+			delta = (u64)(u32)(compare - count - 1) + 1;
+			delta = div_u64(delta * NSEC_PER_SEC,
+					vcpu->arch.count_hz);
+			expire = ktime_add_ns(vcpu->arch.count_resume, delta);
+
+			/* Handle pending interrupt */
+			now = ktime_get();
+			if (ktime_compare(now, expire) >= 0)
+				/* Nothing should be waiting on the timeout */
+				kvm_mips_callbacks->queue_timer_int(vcpu);
+
+			/* Resume hrtimer without changing bias */
+			count = kvm_mips_read_count_running(vcpu, now);
+			kvm_mips_resume_hrtimer(vcpu, now, count);
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * kvm_mips_set_count_resume() - Update the count resume KVM register.
+ * @vcpu:		Virtual CPU.
+ * @count_resume:	Count resume register new value.
+ *
+ * Set the count resume KVM register.
+ *
+ * Returns:	-EINVAL if out of valid range (0..now).
+ *		0 on success.
+ */
+int kvm_mips_set_count_resume(struct kvm_vcpu *vcpu, s64 count_resume)
+{
+	/*
+	 * It doesn't make sense for the resume time to be in the future, as it
+	 * would be possible for the next interrupt to be more than a full
+	 * period in the future.
+	 */
+	if (count_resume < 0 || count_resume > ktime_to_ns(ktime_get()))
+		return -EINVAL;
+
+	vcpu->arch.count_resume = ns_to_ktime(count_resume);
+	return 0;
+}
+
+/**
+ * kvm_mips_count_timeout() - Push timer forward on timeout.
+ * @vcpu:	Virtual CPU.
+ *
+ * Handle an hrtimer event by push the hrtimer forward a period.
+ *
+ * Returns:	The hrtimer_restart value to return to the hrtimer subsystem.
+ */
+enum hrtimer_restart kvm_mips_count_timeout(struct kvm_vcpu *vcpu)
+{
+	/* Add the Count period to the current expiry time */
+	hrtimer_add_expires_ns(&vcpu->arch.comparecount_timer,
+			       vcpu->arch.count_period);
+	return HRTIMER_RESTART;
+}
+
+enum emulation_result kvm_mips_emul_wait(struct kvm_vcpu *vcpu)
+{
+	kvm_debug("[%#lx] !!!WAIT!!! (%#lx)\n", vcpu->arch.pc,
+		  vcpu->arch.pending_exceptions);
+
+	++vcpu->stat.wait_exits;
+	trace_kvm_exit(vcpu, KVM_TRACE_EXIT_WAIT);
+	if (!vcpu->arch.pending_exceptions) {
+		kvm_vz_lose_htimer(vcpu);
+		vcpu->arch.wait = 1;
+		kvm_vcpu_halt(vcpu);
+
+		/*
+		 * We are runnable, then definitely go off to user space to
+		 * check if any I/O interrupts are pending.
+		 */
+		if (kvm_arch_vcpu_runnable(vcpu))
+			vcpu->run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
+	}
+
+	return EMULATE_DONE;
+}
+
+enum emulation_result kvm_mips_emulate_store(union mips_instruction inst,
+					     u32 cause,
+					     struct kvm_vcpu *vcpu)
+{
+	int r;
+	enum emulation_result er;
+	u32 rt;
+	struct kvm_run *run = vcpu->run;
+	void *data = run->mmio.data;
+	unsigned int imme;
+	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.i_format.rt;
+
+	run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+						vcpu->arch.host_cp0_badvaddr);
+	if (run->mmio.phys_addr == KVM_INVALID_ADDR)
+		goto out_fail;
+
+	switch (inst.i_format.opcode) {
+#if defined(CONFIG_64BIT)
+	case sd_op:
+		run->mmio.len = 8;
+		*(u64 *)data = vcpu->arch.gprs[rt];
+
+		kvm_debug("[%#lx] OP_SD: eaddr: %#lx, gpr: %#lx, data: %#llx\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u64 *)data);
+		break;
+#endif
+
+	case sw_op:
+		run->mmio.len = 4;
+		*(u32 *)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], *(u32 *)data);
+		break;
+
+	case sh_op:
+		run->mmio.len = 2;
+		*(u16 *)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], *(u16 *)data);
+		break;
+
+	case sb_op:
+		run->mmio.len = 1;
+		*(u8 *)data = vcpu->arch.gprs[rt];
+
+		kvm_debug("[%#lx] OP_SB: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u8 *)data);
+		break;
+
+	case swl_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x3);
+		run->mmio.len = 4;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x3;
+		switch (imme) {
+		case 0:
+			*(u32 *)data = ((*(u32 *)data) & 0xffffff00) |
+					(vcpu->arch.gprs[rt] >> 24);
+			break;
+		case 1:
+			*(u32 *)data = ((*(u32 *)data) & 0xffff0000) |
+					(vcpu->arch.gprs[rt] >> 16);
+			break;
+		case 2:
+			*(u32 *)data = ((*(u32 *)data) & 0xff000000) |
+					(vcpu->arch.gprs[rt] >> 8);
+			break;
+		case 3:
+			*(u32 *)data = vcpu->arch.gprs[rt];
+			break;
+		default:
+			break;
+		}
+
+		kvm_debug("[%#lx] OP_SWL: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u32 *)data);
+		break;
+
+	case swr_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x3);
+		run->mmio.len = 4;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x3;
+		switch (imme) {
+		case 0:
+			*(u32 *)data = vcpu->arch.gprs[rt];
+			break;
+		case 1:
+			*(u32 *)data = ((*(u32 *)data) & 0xff) |
+					(vcpu->arch.gprs[rt] << 8);
+			break;
+		case 2:
+			*(u32 *)data = ((*(u32 *)data) & 0xffff) |
+					(vcpu->arch.gprs[rt] << 16);
+			break;
+		case 3:
+			*(u32 *)data = ((*(u32 *)data) & 0xffffff) |
+					(vcpu->arch.gprs[rt] << 24);
+			break;
+		default:
+			break;
+		}
+
+		kvm_debug("[%#lx] OP_SWR: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u32 *)data);
+		break;
+
+#if defined(CONFIG_64BIT)
+	case sdl_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x7);
+
+		run->mmio.len = 8;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x7;
+		switch (imme) {
+		case 0:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffffffff00) |
+					((vcpu->arch.gprs[rt] >> 56) & 0xff);
+			break;
+		case 1:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffffff0000) |
+					((vcpu->arch.gprs[rt] >> 48) & 0xffff);
+			break;
+		case 2:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffff000000) |
+					((vcpu->arch.gprs[rt] >> 40) & 0xffffff);
+			break;
+		case 3:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffff00000000) |
+					((vcpu->arch.gprs[rt] >> 32) & 0xffffffff);
+			break;
+		case 4:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffff0000000000) |
+					((vcpu->arch.gprs[rt] >> 24) & 0xffffffffff);
+			break;
+		case 5:
+			*(u64 *)data = ((*(u64 *)data) & 0xffff000000000000) |
+					((vcpu->arch.gprs[rt] >> 16) & 0xffffffffffff);
+			break;
+		case 6:
+			*(u64 *)data = ((*(u64 *)data) & 0xff00000000000000) |
+					((vcpu->arch.gprs[rt] >> 8) & 0xffffffffffffff);
+			break;
+		case 7:
+			*(u64 *)data = vcpu->arch.gprs[rt];
+			break;
+		default:
+			break;
+		}
+
+		kvm_debug("[%#lx] OP_SDL: eaddr: %#lx, gpr: %#lx, data: %llx\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u64 *)data);
+		break;
+
+	case sdr_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x7);
+
+		run->mmio.len = 8;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x7;
+		switch (imme) {
+		case 0:
+			*(u64 *)data = vcpu->arch.gprs[rt];
+			break;
+		case 1:
+			*(u64 *)data = ((*(u64 *)data) & 0xff) |
+					(vcpu->arch.gprs[rt] << 8);
+			break;
+		case 2:
+			*(u64 *)data = ((*(u64 *)data) & 0xffff) |
+					(vcpu->arch.gprs[rt] << 16);
+			break;
+		case 3:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffff) |
+					(vcpu->arch.gprs[rt] << 24);
+			break;
+		case 4:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffff) |
+					(vcpu->arch.gprs[rt] << 32);
+			break;
+		case 5:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffff) |
+					(vcpu->arch.gprs[rt] << 40);
+			break;
+		case 6:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffffff) |
+					(vcpu->arch.gprs[rt] << 48);
+			break;
+		case 7:
+			*(u64 *)data = ((*(u64 *)data) & 0xffffffffffffff) |
+					(vcpu->arch.gprs[rt] << 56);
+			break;
+		default:
+			break;
+		}
+
+		kvm_debug("[%#lx] OP_SDR: eaddr: %#lx, gpr: %#lx, data: %llx\n",
+			  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+			  vcpu->arch.gprs[rt], *(u64 *)data);
+		break;
+#endif
+
+#ifdef CONFIG_CPU_LOONGSON64
+	case sdc2_op:
+		rt = inst.loongson3_lsdc2_format.rt;
+		switch (inst.loongson3_lsdc2_format.opcode1) {
+		/*
+		 * Loongson-3 overridden sdc2 instructions.
+		 * opcode1              instruction
+		 *   0x0          gssbx: store 1 bytes from GPR
+		 *   0x1          gsshx: store 2 bytes from GPR
+		 *   0x2          gsswx: store 4 bytes from GPR
+		 *   0x3          gssdx: store 8 bytes from GPR
+		 */
+		case 0x0:
+			run->mmio.len = 1;
+			*(u8 *)data = vcpu->arch.gprs[rt];
+
+			kvm_debug("[%#lx] OP_GSSBX: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+				  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+				  vcpu->arch.gprs[rt], *(u8 *)data);
+			break;
+		case 0x1:
+			run->mmio.len = 2;
+			*(u16 *)data = vcpu->arch.gprs[rt];
+
+			kvm_debug("[%#lx] OP_GSSSHX: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+				  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+				  vcpu->arch.gprs[rt], *(u16 *)data);
+			break;
+		case 0x2:
+			run->mmio.len = 4;
+			*(u32 *)data = vcpu->arch.gprs[rt];
+
+			kvm_debug("[%#lx] OP_GSSWX: eaddr: %#lx, gpr: %#lx, data: %#x\n",
+				  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+				  vcpu->arch.gprs[rt], *(u32 *)data);
+			break;
+		case 0x3:
+			run->mmio.len = 8;
+			*(u64 *)data = vcpu->arch.gprs[rt];
+
+			kvm_debug("[%#lx] OP_GSSDX: eaddr: %#lx, gpr: %#lx, data: %#llx\n",
+				  vcpu->arch.pc, vcpu->arch.host_cp0_badvaddr,
+				  vcpu->arch.gprs[rt], *(u64 *)data);
+			break;
+		default:
+			kvm_err("Godson Extended GS-Store not yet supported (inst=0x%08x)\n",
+				inst.word);
+			break;
+		}
+		break;
+#endif
+	default:
+		kvm_err("Store not yet supported (inst=0x%08x)\n",
+			inst.word);
+		goto out_fail;
+	}
+
+	vcpu->mmio_needed = 1;
+	run->mmio.is_write = 1;
+	vcpu->mmio_is_write = 1;
+
+	r = kvm_io_bus_write(vcpu, KVM_MMIO_BUS,
+			run->mmio.phys_addr, run->mmio.len, data);
+
+	if (!r) {
+		vcpu->mmio_needed = 0;
+		return EMULATE_DONE;
+	}
+
+	return EMULATE_DO_MMIO;
+
+out_fail:
+	/* Rollback PC if emulation was unsuccessful */
+	vcpu->arch.pc = curr_pc;
+	return EMULATE_FAIL;
+}
+
+enum emulation_result kvm_mips_emulate_load(union mips_instruction inst,
+					    u32 cause, struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+	int r;
+	enum emulation_result er;
+	unsigned long curr_pc;
+	u32 op, rt;
+	unsigned int imme;
+
+	rt = inst.i_format.rt;
+	op = inst.i_format.opcode;
+
+	/*
+	 * Find the resume PC now while we have safe and easy access to the
+	 * prior branch instruction, and save it for
+	 * kvm_mips_complete_mmio_load() to restore later.
+	 */
+	curr_pc = vcpu->arch.pc;
+	er = update_pc(vcpu, cause);
+	if (er == EMULATE_FAIL)
+		return er;
+	vcpu->arch.io_pc = vcpu->arch.pc;
+	vcpu->arch.pc = curr_pc;
+
+	vcpu->arch.io_gpr = rt;
+
+	run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+						vcpu->arch.host_cp0_badvaddr);
+	if (run->mmio.phys_addr == KVM_INVALID_ADDR)
+		return EMULATE_FAIL;
+
+	vcpu->mmio_needed = 2;	/* signed */
+	switch (op) {
+#if defined(CONFIG_64BIT)
+	case ld_op:
+		run->mmio.len = 8;
+		break;
+
+	case lwu_op:
+		vcpu->mmio_needed = 1;	/* unsigned */
+		fallthrough;
+#endif
+	case lw_op:
+		run->mmio.len = 4;
+		break;
+
+	case lhu_op:
+		vcpu->mmio_needed = 1;	/* unsigned */
+		fallthrough;
+	case lh_op:
+		run->mmio.len = 2;
+		break;
+
+	case lbu_op:
+		vcpu->mmio_needed = 1;	/* unsigned */
+		fallthrough;
+	case lb_op:
+		run->mmio.len = 1;
+		break;
+
+	case lwl_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x3);
+
+		run->mmio.len = 4;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x3;
+		switch (imme) {
+		case 0:
+			vcpu->mmio_needed = 3;	/* 1 byte */
+			break;
+		case 1:
+			vcpu->mmio_needed = 4;	/* 2 bytes */
+			break;
+		case 2:
+			vcpu->mmio_needed = 5;	/* 3 bytes */
+			break;
+		case 3:
+			vcpu->mmio_needed = 6;	/* 4 bytes */
+			break;
+		default:
+			break;
+		}
+		break;
+
+	case lwr_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x3);
+
+		run->mmio.len = 4;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x3;
+		switch (imme) {
+		case 0:
+			vcpu->mmio_needed = 7;	/* 4 bytes */
+			break;
+		case 1:
+			vcpu->mmio_needed = 8;	/* 3 bytes */
+			break;
+		case 2:
+			vcpu->mmio_needed = 9;	/* 2 bytes */
+			break;
+		case 3:
+			vcpu->mmio_needed = 10;	/* 1 byte */
+			break;
+		default:
+			break;
+		}
+		break;
+
+#if defined(CONFIG_64BIT)
+	case ldl_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x7);
+
+		run->mmio.len = 8;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x7;
+		switch (imme) {
+		case 0:
+			vcpu->mmio_needed = 11;	/* 1 byte */
+			break;
+		case 1:
+			vcpu->mmio_needed = 12;	/* 2 bytes */
+			break;
+		case 2:
+			vcpu->mmio_needed = 13;	/* 3 bytes */
+			break;
+		case 3:
+			vcpu->mmio_needed = 14;	/* 4 bytes */
+			break;
+		case 4:
+			vcpu->mmio_needed = 15;	/* 5 bytes */
+			break;
+		case 5:
+			vcpu->mmio_needed = 16;	/* 6 bytes */
+			break;
+		case 6:
+			vcpu->mmio_needed = 17;	/* 7 bytes */
+			break;
+		case 7:
+			vcpu->mmio_needed = 18;	/* 8 bytes */
+			break;
+		default:
+			break;
+		}
+		break;
+
+	case ldr_op:
+		run->mmio.phys_addr = kvm_mips_callbacks->gva_to_gpa(
+					vcpu->arch.host_cp0_badvaddr) & (~0x7);
+
+		run->mmio.len = 8;
+		imme = vcpu->arch.host_cp0_badvaddr & 0x7;
+		switch (imme) {
+		case 0:
+			vcpu->mmio_needed = 19;	/* 8 bytes */
+			break;
+		case 1:
+			vcpu->mmio_needed = 20;	/* 7 bytes */
+			break;
+		case 2:
+			vcpu->mmio_needed = 21;	/* 6 bytes */
+			break;
+		case 3:
+			vcpu->mmio_needed = 22;	/* 5 bytes */
+			break;
+		case 4:
+			vcpu->mmio_needed = 23;	/* 4 bytes */
+			break;
+		case 5:
+			vcpu->mmio_needed = 24;	/* 3 bytes */
+			break;
+		case 6:
+			vcpu->mmio_needed = 25;	/* 2 bytes */
+			break;
+		case 7:
+			vcpu->mmio_needed = 26;	/* 1 byte */
+			break;
+		default:
+			break;
+		}
+		break;
+#endif
+
+#ifdef CONFIG_CPU_LOONGSON64
+	case ldc2_op:
+		rt = inst.loongson3_lsdc2_format.rt;
+		switch (inst.loongson3_lsdc2_format.opcode1) {
+		/*
+		 * Loongson-3 overridden ldc2 instructions.
+		 * opcode1              instruction
+		 *   0x0          gslbx: store 1 bytes from GPR
+		 *   0x1          gslhx: store 2 bytes from GPR
+		 *   0x2          gslwx: store 4 bytes from GPR
+		 *   0x3          gsldx: store 8 bytes from GPR
+		 */
+		case 0x0:
+			run->mmio.len = 1;
+			vcpu->mmio_needed = 27;	/* signed */
+			break;
+		case 0x1:
+			run->mmio.len = 2;
+			vcpu->mmio_needed = 28;	/* signed */
+			break;
+		case 0x2:
+			run->mmio.len = 4;
+			vcpu->mmio_needed = 29;	/* signed */
+			break;
+		case 0x3:
+			run->mmio.len = 8;
+			vcpu->mmio_needed = 30;	/* signed */
+			break;
+		default:
+			kvm_err("Godson Extended GS-Load for float not yet supported (inst=0x%08x)\n",
+				inst.word);
+			break;
+		}
+		break;
+#endif
+
+	default:
+		kvm_err("Load not yet supported (inst=0x%08x)\n",
+			inst.word);
+		vcpu->mmio_needed = 0;
+		return EMULATE_FAIL;
+	}
+
+	run->mmio.is_write = 0;
+	vcpu->mmio_is_write = 0;
+
+	r = kvm_io_bus_read(vcpu, KVM_MMIO_BUS,
+			run->mmio.phys_addr, run->mmio.len, run->mmio.data);
+
+	if (!r) {
+		kvm_mips_complete_mmio_load(vcpu);
+		vcpu->mmio_needed = 0;
+		return EMULATE_DONE;
+	}
+
+	return EMULATE_DO_MMIO;
+}
+
+enum emulation_result kvm_mips_complete_mmio_load(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+	unsigned long *gpr = &vcpu->arch.gprs[vcpu->arch.io_gpr];
+	enum emulation_result er = EMULATE_DONE;
+
+	if (run->mmio.len > sizeof(*gpr)) {
+		kvm_err("Bad MMIO length: %d", run->mmio.len);
+		er = EMULATE_FAIL;
+		goto done;
+	}
+
+	/* Restore saved resume PC */
+	vcpu->arch.pc = vcpu->arch.io_pc;
+
+	switch (run->mmio.len) {
+	case 8:
+		switch (vcpu->mmio_needed) {
+		case 11:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffffffff) |
+				(((*(s64 *)run->mmio.data) & 0xff) << 56);
+			break;
+		case 12:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffffff) |
+				(((*(s64 *)run->mmio.data) & 0xffff) << 48);
+			break;
+		case 13:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffff) |
+				(((*(s64 *)run->mmio.data) & 0xffffff) << 40);
+			break;
+		case 14:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffff) |
+				(((*(s64 *)run->mmio.data) & 0xffffffff) << 32);
+			break;
+		case 15:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffff) |
+				(((*(s64 *)run->mmio.data) & 0xffffffffff) << 24);
+			break;
+		case 16:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffff) |
+				(((*(s64 *)run->mmio.data) & 0xffffffffffff) << 16);
+			break;
+		case 17:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xff) |
+				(((*(s64 *)run->mmio.data) & 0xffffffffffffff) << 8);
+			break;
+		case 18:
+		case 19:
+			*gpr = *(s64 *)run->mmio.data;
+			break;
+		case 20:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xff00000000000000) |
+				((((*(s64 *)run->mmio.data)) >> 8) & 0xffffffffffffff);
+			break;
+		case 21:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffff000000000000) |
+				((((*(s64 *)run->mmio.data)) >> 16) & 0xffffffffffff);
+			break;
+		case 22:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffff0000000000) |
+				((((*(s64 *)run->mmio.data)) >> 24) & 0xffffffffff);
+			break;
+		case 23:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffff00000000) |
+				((((*(s64 *)run->mmio.data)) >> 32) & 0xffffffff);
+			break;
+		case 24:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffff000000) |
+				((((*(s64 *)run->mmio.data)) >> 40) & 0xffffff);
+			break;
+		case 25:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffffff0000) |
+				((((*(s64 *)run->mmio.data)) >> 48) & 0xffff);
+			break;
+		case 26:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffffffffffff00) |
+				((((*(s64 *)run->mmio.data)) >> 56) & 0xff);
+			break;
+		default:
+			*gpr = *(s64 *)run->mmio.data;
+		}
+		break;
+
+	case 4:
+		switch (vcpu->mmio_needed) {
+		case 1:
+			*gpr = *(u32 *)run->mmio.data;
+			break;
+		case 2:
+			*gpr = *(s32 *)run->mmio.data;
+			break;
+		case 3:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffff) |
+				(((*(s32 *)run->mmio.data) & 0xff) << 24);
+			break;
+		case 4:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffff) |
+				(((*(s32 *)run->mmio.data) & 0xffff) << 16);
+			break;
+		case 5:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xff) |
+				(((*(s32 *)run->mmio.data) & 0xffffff) << 8);
+			break;
+		case 6:
+		case 7:
+			*gpr = *(s32 *)run->mmio.data;
+			break;
+		case 8:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xff000000) |
+				((((*(s32 *)run->mmio.data)) >> 8) & 0xffffff);
+			break;
+		case 9:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffff0000) |
+				((((*(s32 *)run->mmio.data)) >> 16) & 0xffff);
+			break;
+		case 10:
+			*gpr = (vcpu->arch.gprs[vcpu->arch.io_gpr] & 0xffffff00) |
+				((((*(s32 *)run->mmio.data)) >> 24) & 0xff);
+			break;
+		default:
+			*gpr = *(s32 *)run->mmio.data;
+		}
+		break;
+
+	case 2:
+		if (vcpu->mmio_needed == 1)
+			*gpr = *(u16 *)run->mmio.data;
+		else
+			*gpr = *(s16 *)run->mmio.data;
+
+		break;
+	case 1:
+		if (vcpu->mmio_needed == 1)
+			*gpr = *(u8 *)run->mmio.data;
+		else
+			*gpr = *(s8 *)run->mmio.data;
+		break;
+	}
+
+done:
+	return er;
+}