linux/arch/mips/kvm/tlb.c

/*
 * 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 TLB handling, this file is part of the Linux host kernel so that
 * TLB handlers run from KSEG0
 *
 * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
 * Authors: Sanjay Lal <sanjayl@kymasys.com>
 */

#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/kvm_host.h>
#include <linux/srcu.h>

#include <asm/cpu.h>
#include <asm/bootinfo.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/tlb.h>

#undef CONFIG_MIPS_MT
#include <asm/r4kcache.h>
#define CONFIG_MIPS_MT

#define KVM_GUEST_PC_TLB    0
#define KVM_GUEST_SP_TLB    1

#define PRIx64 "llx"

atomic_t kvm_mips_instance;
EXPORT_SYMBOL(kvm_mips_instance);

/* These function pointers are initialized once the KVM module is loaded */
pfn_t (*kvm_mips_gfn_to_pfn)(struct kvm *kvm, gfn_t gfn);
EXPORT_SYMBOL(kvm_mips_gfn_to_pfn);

void (*kvm_mips_release_pfn_clean)(pfn_t pfn);
EXPORT_SYMBOL(kvm_mips_release_pfn_clean);

bool (*kvm_mips_is_error_pfn)(pfn_t pfn);
EXPORT_SYMBOL(kvm_mips_is_error_pfn);

uint32_t kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)
{
	return vcpu->arch.guest_kernel_asid[smp_processor_id()] & ASID_MASK;
}

uint32_t kvm_mips_get_user_asid(struct kvm_vcpu *vcpu)
{
	return vcpu->arch.guest_user_asid[smp_processor_id()] & ASID_MASK;
}

inline uint32_t kvm_mips_get_commpage_asid(struct kvm_vcpu *vcpu)
{
	return vcpu->kvm->arch.commpage_tlb;
}

/* Structure defining an tlb entry data set. */

void kvm_mips_dump_host_tlbs(void)
{
	unsigned long old_entryhi;
	unsigned long old_pagemask;
	struct kvm_mips_tlb tlb;
	unsigned long flags;
	int i;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();
	old_pagemask = read_c0_pagemask();

	kvm_info("HOST TLBs:\n");
	kvm_info("ASID: %#lx\n", read_c0_entryhi() & ASID_MASK);

	for (i = 0; i < current_cpu_data.tlbsize; i++) {
		write_c0_index(i);
		mtc0_tlbw_hazard();

		tlb_read();
		tlbw_use_hazard();

		tlb.tlb_hi = read_c0_entryhi();
		tlb.tlb_lo0 = read_c0_entrylo0();
		tlb.tlb_lo1 = read_c0_entrylo1();
		tlb.tlb_mask = read_c0_pagemask();

		kvm_info("TLB%c%3d Hi 0x%08lx ",
			 (tlb.tlb_lo0 | tlb.tlb_lo1) & MIPS3_PG_V ? ' ' : '*',
			 i, tlb.tlb_hi);
		kvm_info("Lo0=0x%09" PRIx64 " %c%c attr %lx ",
			 (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo0),
			 (tlb.tlb_lo0 & MIPS3_PG_D) ? 'D' : ' ',
			 (tlb.tlb_lo0 & MIPS3_PG_G) ? 'G' : ' ',
			 (tlb.tlb_lo0 >> 3) & 7);
		kvm_info("Lo1=0x%09" PRIx64 " %c%c attr %lx sz=%lx\n",
			 (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo1),
			 (tlb.tlb_lo1 & MIPS3_PG_D) ? 'D' : ' ',
			 (tlb.tlb_lo1 & MIPS3_PG_G) ? 'G' : ' ',
			 (tlb.tlb_lo1 >> 3) & 7, tlb.tlb_mask);
	}
	write_c0_entryhi(old_entryhi);
	write_c0_pagemask(old_pagemask);
	mtc0_tlbw_hazard();
	local_irq_restore(flags);
}
EXPORT_SYMBOL(kvm_mips_dump_host_tlbs);

void kvm_mips_dump_guest_tlbs(struct kvm_vcpu *vcpu)
{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	struct kvm_mips_tlb tlb;
	int i;

	kvm_info("Guest TLBs:\n");
	kvm_info("Guest EntryHi: %#lx\n", kvm_read_c0_guest_entryhi(cop0));

	for (i = 0; i < KVM_MIPS_GUEST_TLB_SIZE; i++) {
		tlb = vcpu->arch.guest_tlb[i];
		kvm_info("TLB%c%3d Hi 0x%08lx ",
			 (tlb.tlb_lo0 | tlb.tlb_lo1) & MIPS3_PG_V ? ' ' : '*',
			 i, tlb.tlb_hi);
		kvm_info("Lo0=0x%09" PRIx64 " %c%c attr %lx ",
			 (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo0),
			 (tlb.tlb_lo0 & MIPS3_PG_D) ? 'D' : ' ',
			 (tlb.tlb_lo0 & MIPS3_PG_G) ? 'G' : ' ',
			 (tlb.tlb_lo0 >> 3) & 7);
		kvm_info("Lo1=0x%09" PRIx64 " %c%c attr %lx sz=%lx\n",
			 (uint64_t) mips3_tlbpfn_to_paddr(tlb.tlb_lo1),
			 (tlb.tlb_lo1 & MIPS3_PG_D) ? 'D' : ' ',
			 (tlb.tlb_lo1 & MIPS3_PG_G) ? 'G' : ' ',
			 (tlb.tlb_lo1 >> 3) & 7, tlb.tlb_mask);
	}
}
EXPORT_SYMBOL(kvm_mips_dump_guest_tlbs);

static int kvm_mips_map_page(struct kvm *kvm, gfn_t gfn)
{
	int srcu_idx, err = 0;
	pfn_t pfn;

	if (kvm->arch.guest_pmap[gfn] != KVM_INVALID_PAGE)
		return 0;

	srcu_idx = srcu_read_lock(&kvm->srcu);
	pfn = kvm_mips_gfn_to_pfn(kvm, gfn);

	if (kvm_mips_is_error_pfn(pfn)) {
		kvm_err("Couldn't get pfn for gfn %#" PRIx64 "!\n", gfn);
		err = -EFAULT;
		goto out;
	}

	kvm->arch.guest_pmap[gfn] = pfn;
out:
	srcu_read_unlock(&kvm->srcu, srcu_idx);
	return err;
}

/* Translate guest KSEG0 addresses to Host PA */
unsigned long kvm_mips_translate_guest_kseg0_to_hpa(struct kvm_vcpu *vcpu,
						    unsigned long gva)
{
	gfn_t gfn;
	uint32_t offset = gva & ~PAGE_MASK;
	struct kvm *kvm = vcpu->kvm;

	if (KVM_GUEST_KSEGX(gva) != KVM_GUEST_KSEG0) {
		kvm_err("%s/%p: Invalid gva: %#lx\n", __func__,
			__builtin_return_address(0), gva);
		return KVM_INVALID_PAGE;
	}

	gfn = (KVM_GUEST_CPHYSADDR(gva) >> PAGE_SHIFT);

	if (gfn >= kvm->arch.guest_pmap_npages) {
		kvm_err("%s: Invalid gfn: %#llx, GVA: %#lx\n", __func__, gfn,
			gva);
		return KVM_INVALID_PAGE;
	}

	if (kvm_mips_map_page(vcpu->kvm, gfn) < 0)
		return KVM_INVALID_ADDR;

	return (kvm->arch.guest_pmap[gfn] << PAGE_SHIFT) + offset;
}
EXPORT_SYMBOL(kvm_mips_translate_guest_kseg0_to_hpa);

/* XXXKYMA: Must be called with interrupts disabled */
/* set flush_dcache_mask == 0 if no dcache flush required */
int kvm_mips_host_tlb_write(struct kvm_vcpu *vcpu, unsigned long entryhi,
			    unsigned long entrylo0, unsigned long entrylo1,
			    int flush_dcache_mask)
{
	unsigned long flags;
	unsigned long old_entryhi;
	int idx;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();
	write_c0_entryhi(entryhi);
	mtc0_tlbw_hazard();

	tlb_probe();
	tlb_probe_hazard();
	idx = read_c0_index();

	if (idx > current_cpu_data.tlbsize) {
		kvm_err("%s: Invalid Index: %d\n", __func__, idx);
		kvm_mips_dump_host_tlbs();
		local_irq_restore(flags);
		return -1;
	}

	write_c0_entrylo0(entrylo0);
	write_c0_entrylo1(entrylo1);
	mtc0_tlbw_hazard();

	if (idx < 0)
		tlb_write_random();
	else
		tlb_write_indexed();
	tlbw_use_hazard();

	kvm_debug("@ %#lx idx: %2d [entryhi(R): %#lx] entrylo0(R): 0x%08lx, entrylo1(R): 0x%08lx\n",
		  vcpu->arch.pc, idx, read_c0_entryhi(),
		  read_c0_entrylo0(), read_c0_entrylo1());

	/* Flush D-cache */
	if (flush_dcache_mask) {
		if (entrylo0 & MIPS3_PG_V) {
			++vcpu->stat.flush_dcache_exits;
			flush_data_cache_page((entryhi & VPN2_MASK) &
					      ~flush_dcache_mask);
		}
		if (entrylo1 & MIPS3_PG_V) {
			++vcpu->stat.flush_dcache_exits;
			flush_data_cache_page(((entryhi & VPN2_MASK) &
					       ~flush_dcache_mask) |
					      (0x1 << PAGE_SHIFT));
		}
	}

	/* Restore old ASID */
	write_c0_entryhi(old_entryhi);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();
	local_irq_restore(flags);
	return 0;
}

/* XXXKYMA: Must be called with interrupts disabled */
int kvm_mips_handle_kseg0_tlb_fault(unsigned long badvaddr,
				    struct kvm_vcpu *vcpu)
{
	gfn_t gfn;
	pfn_t pfn0, pfn1;
	unsigned long vaddr = 0;
	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
	int even;
	struct kvm *kvm = vcpu->kvm;
	const int flush_dcache_mask = 0;

	if (KVM_GUEST_KSEGX(badvaddr) != KVM_GUEST_KSEG0) {
		kvm_err("%s: Invalid BadVaddr: %#lx\n", __func__, badvaddr);
		kvm_mips_dump_host_tlbs();
		return -1;
	}

	gfn = (KVM_GUEST_CPHYSADDR(badvaddr) >> PAGE_SHIFT);
	if (gfn >= kvm->arch.guest_pmap_npages) {
		kvm_err("%s: Invalid gfn: %#llx, BadVaddr: %#lx\n", __func__,
			gfn, badvaddr);
		kvm_mips_dump_host_tlbs();
		return -1;
	}
	even = !(gfn & 0x1);
	vaddr = badvaddr & (PAGE_MASK << 1);

	if (kvm_mips_map_page(vcpu->kvm, gfn) < 0)
		return -1;

	if (kvm_mips_map_page(vcpu->kvm, gfn ^ 0x1) < 0)
		return -1;

	if (even) {
		pfn0 = kvm->arch.guest_pmap[gfn];
		pfn1 = kvm->arch.guest_pmap[gfn ^ 0x1];
	} else {
		pfn0 = kvm->arch.guest_pmap[gfn ^ 0x1];
		pfn1 = kvm->arch.guest_pmap[gfn];
	}

	entryhi = (vaddr | kvm_mips_get_kernel_asid(vcpu));
	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
		   (1 << 2) | (0x1 << 1);
	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
		   (1 << 2) | (0x1 << 1);

	return kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
				       flush_dcache_mask);
}
EXPORT_SYMBOL(kvm_mips_handle_kseg0_tlb_fault);

int kvm_mips_handle_commpage_tlb_fault(unsigned long badvaddr,
	struct kvm_vcpu *vcpu)
{
	pfn_t pfn0, pfn1;
	unsigned long flags, old_entryhi = 0, vaddr = 0;
	unsigned long entrylo0 = 0, entrylo1 = 0;

	pfn0 = CPHYSADDR(vcpu->arch.kseg0_commpage) >> PAGE_SHIFT;
	pfn1 = 0;
	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
		   (1 << 2) | (0x1 << 1);
	entrylo1 = 0;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();
	vaddr = badvaddr & (PAGE_MASK << 1);
	write_c0_entryhi(vaddr | kvm_mips_get_kernel_asid(vcpu));
	mtc0_tlbw_hazard();
	write_c0_entrylo0(entrylo0);
	mtc0_tlbw_hazard();
	write_c0_entrylo1(entrylo1);
	mtc0_tlbw_hazard();
	write_c0_index(kvm_mips_get_commpage_asid(vcpu));
	mtc0_tlbw_hazard();
	tlb_write_indexed();
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	kvm_debug("@ %#lx idx: %2d [entryhi(R): %#lx] entrylo0 (R): 0x%08lx, entrylo1(R): 0x%08lx\n",
		  vcpu->arch.pc, read_c0_index(), read_c0_entryhi(),
		  read_c0_entrylo0(), read_c0_entrylo1());

	/* Restore old ASID */
	write_c0_entryhi(old_entryhi);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();
	local_irq_restore(flags);

	return 0;
}
EXPORT_SYMBOL(kvm_mips_handle_commpage_tlb_fault);

int kvm_mips_handle_mapped_seg_tlb_fault(struct kvm_vcpu *vcpu,
					 struct kvm_mips_tlb *tlb,
					 unsigned long *hpa0,
					 unsigned long *hpa1)
{
	unsigned long entryhi = 0, entrylo0 = 0, entrylo1 = 0;
	struct kvm *kvm = vcpu->kvm;
	pfn_t pfn0, pfn1;

	if ((tlb->tlb_hi & VPN2_MASK) == 0) {
		pfn0 = 0;
		pfn1 = 0;
	} else {
		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
					   >> PAGE_SHIFT) < 0)
			return -1;

		if (kvm_mips_map_page(kvm, mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
					   >> PAGE_SHIFT) < 0)
			return -1;

		pfn0 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo0)
					    >> PAGE_SHIFT];
		pfn1 = kvm->arch.guest_pmap[mips3_tlbpfn_to_paddr(tlb->tlb_lo1)
					    >> PAGE_SHIFT];
	}

	if (hpa0)
		*hpa0 = pfn0 << PAGE_SHIFT;

	if (hpa1)
		*hpa1 = pfn1 << PAGE_SHIFT;

	/* Get attributes from the Guest TLB */
	entryhi = (tlb->tlb_hi & VPN2_MASK) | (KVM_GUEST_KERNEL_MODE(vcpu) ?
					       kvm_mips_get_kernel_asid(vcpu) :
					       kvm_mips_get_user_asid(vcpu));
	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) | (0x3 << 3) |
		   (tlb->tlb_lo0 & MIPS3_PG_D) | (tlb->tlb_lo0 & MIPS3_PG_V);
	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) | (0x3 << 3) |
		   (tlb->tlb_lo1 & MIPS3_PG_D) | (tlb->tlb_lo1 & MIPS3_PG_V);

	kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
		  tlb->tlb_lo0, tlb->tlb_lo1);

	return kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
				       tlb->tlb_mask);
}
EXPORT_SYMBOL(kvm_mips_handle_mapped_seg_tlb_fault);

int kvm_mips_guest_tlb_lookup(struct kvm_vcpu *vcpu, unsigned long entryhi)
{
	int i;
	int index = -1;
	struct kvm_mips_tlb *tlb = vcpu->arch.guest_tlb;

	for (i = 0; i < KVM_MIPS_GUEST_TLB_SIZE; i++) {
		if (TLB_HI_VPN2_HIT(tlb[i], entryhi) &&
		    TLB_HI_ASID_HIT(tlb[i], entryhi)) {
			index = i;
			break;
		}
	}

	kvm_debug("%s: entryhi: %#lx, index: %d lo0: %#lx, lo1: %#lx\n",
		  __func__, entryhi, index, tlb[i].tlb_lo0, tlb[i].tlb_lo1);

	return index;
}
EXPORT_SYMBOL(kvm_mips_guest_tlb_lookup);

int kvm_mips_host_tlb_lookup(struct kvm_vcpu *vcpu, unsigned long vaddr)
{
	unsigned long old_entryhi, flags;
	int idx;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();

	if (KVM_GUEST_KERNEL_MODE(vcpu))
		write_c0_entryhi((vaddr & VPN2_MASK) |
				 kvm_mips_get_kernel_asid(vcpu));
	else {
		write_c0_entryhi((vaddr & VPN2_MASK) |
				 kvm_mips_get_user_asid(vcpu));
	}

	mtc0_tlbw_hazard();

	tlb_probe();
	tlb_probe_hazard();
	idx = read_c0_index();

	/* Restore old ASID */
	write_c0_entryhi(old_entryhi);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	local_irq_restore(flags);

	kvm_debug("Host TLB lookup, %#lx, idx: %2d\n", vaddr, idx);

	return idx;
}
EXPORT_SYMBOL(kvm_mips_host_tlb_lookup);

int kvm_mips_host_tlb_inv(struct kvm_vcpu *vcpu, unsigned long va)
{
	int idx;
	unsigned long flags, old_entryhi;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();

	write_c0_entryhi((va & VPN2_MASK) | kvm_mips_get_user_asid(vcpu));
	mtc0_tlbw_hazard();

	tlb_probe();
	tlb_probe_hazard();
	idx = read_c0_index();

	if (idx >= current_cpu_data.tlbsize)
		BUG();

	if (idx > 0) {
		write_c0_entryhi(UNIQUE_ENTRYHI(idx));
		mtc0_tlbw_hazard();

		write_c0_entrylo0(0);
		mtc0_tlbw_hazard();

		write_c0_entrylo1(0);
		mtc0_tlbw_hazard();

		tlb_write_indexed();
		mtc0_tlbw_hazard();
	}

	write_c0_entryhi(old_entryhi);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	local_irq_restore(flags);

	if (idx > 0)
		kvm_debug("%s: Invalidated entryhi %#lx @ idx %d\n", __func__,
			  (va & VPN2_MASK) | kvm_mips_get_user_asid(vcpu), idx);

	return 0;
}
EXPORT_SYMBOL(kvm_mips_host_tlb_inv);

/* XXXKYMA: Fix Guest USER/KERNEL no longer share the same ASID */
int kvm_mips_host_tlb_inv_index(struct kvm_vcpu *vcpu, int index)
{
	unsigned long flags, old_entryhi;

	if (index >= current_cpu_data.tlbsize)
		BUG();

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();

	write_c0_entryhi(UNIQUE_ENTRYHI(index));
	mtc0_tlbw_hazard();

	write_c0_index(index);
	mtc0_tlbw_hazard();

	write_c0_entrylo0(0);
	mtc0_tlbw_hazard();

	write_c0_entrylo1(0);
	mtc0_tlbw_hazard();

	tlb_write_indexed();
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	write_c0_entryhi(old_entryhi);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	local_irq_restore(flags);

	return 0;
}

void kvm_mips_flush_host_tlb(int skip_kseg0)
{
	unsigned long flags;
	unsigned long old_entryhi, entryhi;
	unsigned long old_pagemask;
	int entry = 0;
	int maxentry = current_cpu_data.tlbsize;

	local_irq_save(flags);

	old_entryhi = read_c0_entryhi();
	old_pagemask = read_c0_pagemask();

	/* Blast 'em all away. */
	for (entry = 0; entry < maxentry; entry++) {
		write_c0_index(entry);
		mtc0_tlbw_hazard();

		if (skip_kseg0) {
			tlb_read();
			tlbw_use_hazard();

			entryhi = read_c0_entryhi();

			/* Don't blow away guest kernel entries */
			if (KVM_GUEST_KSEGX(entryhi) == KVM_GUEST_KSEG0)
				continue;
		}

		/* Make sure all entries differ. */
		write_c0_entryhi(UNIQUE_ENTRYHI(entry));
		mtc0_tlbw_hazard();
		write_c0_entrylo0(0);
		mtc0_tlbw_hazard();
		write_c0_entrylo1(0);
		mtc0_tlbw_hazard();

		tlb_write_indexed();
		mtc0_tlbw_hazard();
	}

	tlbw_use_hazard();

	write_c0_entryhi(old_entryhi);
	write_c0_pagemask(old_pagemask);
	mtc0_tlbw_hazard();
	tlbw_use_hazard();

	local_irq_restore(flags);
}
EXPORT_SYMBOL(kvm_mips_flush_host_tlb);

void kvm_get_new_mmu_context(struct mm_struct *mm, unsigned long cpu,
			     struct kvm_vcpu *vcpu)
{
	unsigned long asid = asid_cache(cpu);

	asid += ASID_INC;
	if (!(asid & ASID_MASK)) {
		if (cpu_has_vtag_icache)
			flush_icache_all();

		kvm_local_flush_tlb_all();      /* start new asid cycle */

		if (!asid)      /* fix version if needed */
			asid = ASID_FIRST_VERSION;
	}

	cpu_context(cpu, mm) = asid_cache(cpu) = asid;
}

void kvm_local_flush_tlb_all(void)
{
	unsigned long flags;
	unsigned long old_ctx;
	int entry = 0;

	local_irq_save(flags);
	/* Save old context and create impossible VPN2 value */
	old_ctx = read_c0_entryhi();
	write_c0_entrylo0(0);
	write_c0_entrylo1(0);

	/* Blast 'em all away. */
	while (entry < current_cpu_data.tlbsize) {
		/* Make sure all entries differ. */
		write_c0_entryhi(UNIQUE_ENTRYHI(entry));
		write_c0_index(entry);
		mtc0_tlbw_hazard();
		tlb_write_indexed();
		entry++;
	}
	tlbw_use_hazard();
	write_c0_entryhi(old_ctx);
	mtc0_tlbw_hazard();

	local_irq_restore(flags);
}
EXPORT_SYMBOL(kvm_local_flush_tlb_all);

/**
 * kvm_mips_migrate_count() - Migrate timer.
 * @vcpu:	Virtual CPU.
 *
 * Migrate CP0_Count hrtimer to the current CPU by cancelling and restarting it
 * if it was running prior to being cancelled.
 *
 * Must be called when the VCPU is migrated to a different CPU to ensure that
 * timer expiry during guest execution interrupts the guest and causes the
 * interrupt to be delivered in a timely manner.
 */
static void kvm_mips_migrate_count(struct kvm_vcpu *vcpu)
{
	if (hrtimer_cancel(&vcpu->arch.comparecount_timer))
		hrtimer_restart(&vcpu->arch.comparecount_timer);
}

/* Restore ASID once we are scheduled back after preemption */
void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
	unsigned long flags;
	int newasid = 0;

	kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);

	/* Alocate new kernel and user ASIDs if needed */

	local_irq_save(flags);

	if (((vcpu->arch.
	      guest_kernel_asid[cpu] ^ asid_cache(cpu)) & ASID_VERSION_MASK)) {
		kvm_get_new_mmu_context(&vcpu->arch.guest_kernel_mm, cpu, vcpu);
		vcpu->arch.guest_kernel_asid[cpu] =
		    vcpu->arch.guest_kernel_mm.context.asid[cpu];
		kvm_get_new_mmu_context(&vcpu->arch.guest_user_mm, cpu, vcpu);
		vcpu->arch.guest_user_asid[cpu] =
		    vcpu->arch.guest_user_mm.context.asid[cpu];
		newasid++;

		kvm_debug("[%d]: cpu_context: %#lx\n", cpu,
			  cpu_context(cpu, current->mm));
		kvm_debug("[%d]: Allocated new ASID for Guest Kernel: %#x\n",
			  cpu, vcpu->arch.guest_kernel_asid[cpu]);
		kvm_debug("[%d]: Allocated new ASID for Guest User: %#x\n", cpu,
			  vcpu->arch.guest_user_asid[cpu]);
	}

	if (vcpu->arch.last_sched_cpu != cpu) {
		kvm_debug("[%d->%d]KVM VCPU[%d] switch\n",
			  vcpu->arch.last_sched_cpu, cpu, vcpu->vcpu_id);
		/*
		 * Migrate the timer interrupt to the current CPU so that it
		 * always interrupts the guest and synchronously triggers a
		 * guest timer interrupt.
		 */
		kvm_mips_migrate_count(vcpu);
	}

	if (!newasid) {
		/*
		 * If we preempted while the guest was executing, then reload
		 * the pre-empted ASID
		 */
		if (current->flags & PF_VCPU) {
			write_c0_entryhi(vcpu->arch.
					 preempt_entryhi & ASID_MASK);
			ehb();
		}
	} else {
		/* New ASIDs were allocated for the VM */

		/*
		 * Were we in guest context? If so then the pre-empted ASID is
		 * no longer valid, we need to set it to what it should be based
		 * on the mode of the Guest (Kernel/User)
		 */
		if (current->flags & PF_VCPU) {
			if (KVM_GUEST_KERNEL_MODE(vcpu))
				write_c0_entryhi(vcpu->arch.
						 guest_kernel_asid[cpu] &
						 ASID_MASK);
			else
				write_c0_entryhi(vcpu->arch.
						 guest_user_asid[cpu] &
						 ASID_MASK);
			ehb();
		}
	}

	/* restore guest state to registers */
	kvm_mips_callbacks->vcpu_set_regs(vcpu);

	local_irq_restore(flags);

}
EXPORT_SYMBOL(kvm_arch_vcpu_load);

/* ASID can change if another task is scheduled during preemption */
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
	unsigned long flags;
	uint32_t cpu;

	local_irq_save(flags);

	cpu = smp_processor_id();

	vcpu->arch.preempt_entryhi = read_c0_entryhi();
	vcpu->arch.last_sched_cpu = cpu;

	/* save guest state in registers */
	kvm_mips_callbacks->vcpu_get_regs(vcpu);

	if (((cpu_context(cpu, current->mm) ^ asid_cache(cpu)) &
	     ASID_VERSION_MASK)) {
		kvm_debug("%s: Dropping MMU Context:  %#lx\n", __func__,
			  cpu_context(cpu, current->mm));
		drop_mmu_context(current->mm, cpu);
	}
	write_c0_entryhi(cpu_asid(cpu, current->mm));
	ehb();

	local_irq_restore(flags);
}
EXPORT_SYMBOL(kvm_arch_vcpu_put);

uint32_t kvm_get_inst(uint32_t *opc, struct kvm_vcpu *vcpu)
{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	unsigned long paddr, flags, vpn2, asid;
	uint32_t inst;
	int index;

	if (KVM_GUEST_KSEGX((unsigned long) opc) < KVM_GUEST_KSEG0 ||
	    KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
		local_irq_save(flags);
		index = kvm_mips_host_tlb_lookup(vcpu, (unsigned long) opc);
		if (index >= 0) {
			inst = *(opc);
		} else {
			vpn2 = (unsigned long) opc & VPN2_MASK;
			asid = kvm_read_c0_guest_entryhi(cop0) & ASID_MASK;
			index = kvm_mips_guest_tlb_lookup(vcpu, vpn2 | asid);
			if (index < 0) {
				kvm_err("%s: get_user_failed for %p, vcpu: %p, ASID: %#lx\n",
					__func__, opc, vcpu, read_c0_entryhi());
				kvm_mips_dump_host_tlbs();
				local_irq_restore(flags);
				return KVM_INVALID_INST;
			}
			kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
							     &vcpu->arch.
							     guest_tlb[index],
							     NULL, NULL);
			inst = *(opc);
		}
		local_irq_restore(flags);
	} else if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
		paddr =
		    kvm_mips_translate_guest_kseg0_to_hpa(vcpu,
							  (unsigned long) opc);
		inst = *(uint32_t *) CKSEG0ADDR(paddr);
	} else {
		kvm_err("%s: illegal address: %p\n", __func__, opc);
		return KVM_INVALID_INST;
	}

	return inst;
}
EXPORT_SYMBOL(kvm_get_inst);