arch/mips/kvm/mmu.c - pub/scm/linux/kernel/git/jhogan/linux - Git at Google

 /*
  * 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 MMU handling in the KVM module.
  *
  * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
  * Authors: Sanjay Lal <sanjayl@kymasys.com>
  */

 #include <linux/highmem.h>
 #include <linux/kvm_host.h>
 #include <asm/mmu_context.h>

 static u32 kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)
 {
 	int cpu = smp_processor_id();

 	return vcpu->arch.guest_kernel_asid[cpu] &
 			cpu_asid_mask(&cpu_data[cpu]);
 }

 static u32 kvm_mips_get_user_asid(struct kvm_vcpu *vcpu)
 {
 	int cpu = smp_processor_id();

 	return vcpu->arch.guest_user_asid[cpu] &
 			cpu_asid_mask(&cpu_data[cpu]);
 }

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

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

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

 	if (is_error_pfn(pfn)) {
 		kvm_err("Couldn't get pfn for gfn %#llx!\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;
 	unsigned long 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;
 }

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

 	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;
 	}
 	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;

 	pfn0 = kvm->arch.guest_pmap[gfn & ~0x1];
 	pfn1 = kvm->arch.guest_pmap[gfn | 0x1];

 	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) |
 		((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
 		ENTRYLO_D | ENTRYLO_V;
 	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) |
 		((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
 		ENTRYLO_D | ENTRYLO_V;

 	preempt_disable();
 	entryhi = (vaddr | kvm_mips_get_kernel_asid(vcpu));
 	ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
 				      flush_dcache_mask);
 	preempt_enable();

 	return ret;
 }

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

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

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

 		pfn0 = kvm->arch.guest_pmap[
 			mips3_tlbpfn_to_paddr(tlb->tlb_lo[0]) >> PAGE_SHIFT];
 		pfn1 = kvm->arch.guest_pmap[
 			mips3_tlbpfn_to_paddr(tlb->tlb_lo[1]) >> PAGE_SHIFT];
 	}

 	/* Get attributes from the Guest TLB */
 	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) |
 		((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
 		(tlb->tlb_lo[0] & ENTRYLO_D) |
 		(tlb->tlb_lo[0] & ENTRYLO_V);
 	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) |
 		((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
 		(tlb->tlb_lo[1] & ENTRYLO_D) |
 		(tlb->tlb_lo[1] & ENTRYLO_V);

 	kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
 		  tlb->tlb_lo[0], tlb->tlb_lo[1]);

 	preempt_disable();
 	entryhi = (tlb->tlb_hi & VPN2_MASK) | (KVM_GUEST_KERNEL_MODE(vcpu) ?
 					       kvm_mips_get_kernel_asid(vcpu) :
 					       kvm_mips_get_user_asid(vcpu));
 	ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
 				      tlb->tlb_mask);
 	preempt_enable();

 	return ret;
 }

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

 	asid += cpu_asid_inc();
 	if (!(asid & cpu_asid_mask(&cpu_data[cpu]))) {
 		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);
 	}

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

 /**
  * 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 asid_mask = cpu_asid_mask(&cpu_data[cpu]);
 	unsigned long flags;
 	int newasid = 0;

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

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

 	local_irq_save(flags);

 	if ((vcpu->arch.guest_kernel_asid[cpu] ^ asid_cache(cpu)) &
 						asid_version_mask(cpu)) {
 		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);

 }

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

 u32 kvm_get_inst(u32 *opc, struct kvm_vcpu *vcpu)
 {
 	struct mips_coproc *cop0 = vcpu->arch.cop0;
 	unsigned long paddr, flags, vpn2, asid;
 	unsigned long va = (unsigned long)opc;
 	void *vaddr;
 	u32 inst;
 	int index;

 	if (KVM_GUEST_KSEGX(va) < KVM_GUEST_KSEG0 ||
 	    KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG23) {
 		local_irq_save(flags);
 		index = kvm_mips_host_tlb_lookup(vcpu, va);
 		if (index >= 0) {
 			inst = *(opc);
 		} else {
 			vpn2 = va & VPN2_MASK;
 			asid = kvm_read_c0_guest_entryhi(cop0) &
 						KVM_ENTRYHI_ASID;
 			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();
 				kvm_mips_dump_guest_tlbs(vcpu);
 				local_irq_restore(flags);
 				return KVM_INVALID_INST;
 			}
 			kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
 							     &vcpu->arch.
 							     guest_tlb[index]);
 			inst = *(opc);
 		}
 		local_irq_restore(flags);
 	} else if (KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG0) {
 		paddr = kvm_mips_translate_guest_kseg0_to_hpa(vcpu, va);
 		vaddr = kmap_atomic(pfn_to_page(PHYS_PFN(paddr)));
 		vaddr += paddr & ~PAGE_MASK;
 		inst = *(u32 *)vaddr;
 		kunmap_atomic(vaddr);
 	} else {
 		kvm_err("%s: illegal address: %p\n", __func__, opc);
 		return KVM_INVALID_INST;
 	}

 	return inst;
 }
	/*
	* 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 MMU handling in the KVM module.
	*
	* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
	* Authors: Sanjay Lal <sanjayl@kymasys.com>
	*/

	#include <linux/highmem.h>
	#include <linux/kvm_host.h>
	#include <asm/mmu_context.h>

	static u32 kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)
	{
	int cpu = smp_processor_id();

	return vcpu->arch.guest_kernel_asid[cpu] &
	cpu_asid_mask(&cpu_data[cpu]);
	}

	static u32 kvm_mips_get_user_asid(struct kvm_vcpu *vcpu)
	{
	int cpu = smp_processor_id();

	return vcpu->arch.guest_user_asid[cpu] &
	cpu_asid_mask(&cpu_data[cpu]);
	}

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

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

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

	if (is_error_pfn(pfn)) {
	kvm_err("Couldn't get pfn for gfn %#llx!\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;
	unsigned long 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;
	}

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

	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;
	}
	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;

	pfn0 = kvm->arch.guest_pmap[gfn & ~0x1];
	pfn1 = kvm->arch.guest_pmap[gfn \| 0x1];

	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) \|
	((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) \|
	ENTRYLO_D \| ENTRYLO_V;
	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) \|
	((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) \|
	ENTRYLO_D \| ENTRYLO_V;

	preempt_disable();
	entryhi = (vaddr \| kvm_mips_get_kernel_asid(vcpu));
	ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
	flush_dcache_mask);
	preempt_enable();

	return ret;
	}

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

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

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

	pfn0 = kvm->arch.guest_pmap[
	mips3_tlbpfn_to_paddr(tlb->tlb_lo[0]) >> PAGE_SHIFT];
	pfn1 = kvm->arch.guest_pmap[
	mips3_tlbpfn_to_paddr(tlb->tlb_lo[1]) >> PAGE_SHIFT];
	}

	/* Get attributes from the Guest TLB */
	entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) \|
	((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) \|
	(tlb->tlb_lo[0] & ENTRYLO_D) \|
	(tlb->tlb_lo[0] & ENTRYLO_V);
	entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) \|
	((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) \|
	(tlb->tlb_lo[1] & ENTRYLO_D) \|
	(tlb->tlb_lo[1] & ENTRYLO_V);

	kvm_debug("@ %#lx tlb_lo0: 0x%08lx tlb_lo1: 0x%08lx\n", vcpu->arch.pc,
	tlb->tlb_lo[0], tlb->tlb_lo[1]);

	preempt_disable();
	entryhi = (tlb->tlb_hi & VPN2_MASK) \| (KVM_GUEST_KERNEL_MODE(vcpu) ?
	kvm_mips_get_kernel_asid(vcpu) :
	kvm_mips_get_user_asid(vcpu));
	ret = kvm_mips_host_tlb_write(vcpu, entryhi, entrylo0, entrylo1,
	tlb->tlb_mask);
	preempt_enable();

	return ret;
	}

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

	asid += cpu_asid_inc();
	if (!(asid & cpu_asid_mask(&cpu_data[cpu]))) {
	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);
	}

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

	/**
	* 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 asid_mask = cpu_asid_mask(&cpu_data[cpu]);
	unsigned long flags;
	int newasid = 0;

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

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

	local_irq_save(flags);

	if ((vcpu->arch.guest_kernel_asid[cpu] ^ asid_cache(cpu)) &
	asid_version_mask(cpu)) {
	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);

	}

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

	u32 kvm_get_inst(u32 opc, struct kvm_vcpu vcpu)
	{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	unsigned long paddr, flags, vpn2, asid;
	unsigned long va = (unsigned long)opc;
	void *vaddr;
	u32 inst;
	int index;

	if (KVM_GUEST_KSEGX(va) < KVM_GUEST_KSEG0 \|\|
	KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG23) {
	local_irq_save(flags);
	index = kvm_mips_host_tlb_lookup(vcpu, va);
	if (index >= 0) {
	inst = *(opc);
	} else {
	vpn2 = va & VPN2_MASK;
	asid = kvm_read_c0_guest_entryhi(cop0) &
	KVM_ENTRYHI_ASID;
	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();
	kvm_mips_dump_guest_tlbs(vcpu);
	local_irq_restore(flags);
	return KVM_INVALID_INST;
	}
	kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
	&vcpu->arch.
	guest_tlb[index]);
	inst = *(opc);
	}
	local_irq_restore(flags);
	} else if (KVM_GUEST_KSEGX(va) == KVM_GUEST_KSEG0) {
	paddr = kvm_mips_translate_guest_kseg0_to_hpa(vcpu, va);
	vaddr = kmap_atomic(pfn_to_page(PHYS_PFN(paddr)));
	vaddr += paddr & ~PAGE_MASK;
	inst = (u32 )vaddr;
	kunmap_atomic(vaddr);
	} else {
	kvm_err("%s: illegal address: %p\n", __func__, opc);
	return KVM_INVALID_INST;
	}

	return inst;
	}