book3s_64_mmu_hv.c

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/highmem.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/vmalloc.h>

#include <asm/tlbflush.h>
#include <asm/kvm_ppc.h>
#include <asm/kvm_book3s.h>
#include <asm/mmu-hash64.h>
#include <asm/hvcall.h>
#include <asm/synch.h>
#include <asm/ppc-opcode.h>
#include <asm/cputable.h>

/* POWER7 has 10-bit LPIDs, PPC970 has 6-bit LPIDs */
#define MAX_LPID_970	63
#define NR_LPIDS	(LPID_RSVD + 1)
unsigned long lpid_inuse[BITS_TO_LONGS(NR_LPIDS)];

long kvmppc_alloc_hpt(struct kvm *kvm)
{
	unsigned long hpt;
	unsigned long lpid;
	struct revmap_entry *rev;

	/* Allocate guest's hashed page table */
	hpt = __get_free_pages(GFP_KERNEL|__GFP_ZERO|__GFP_REPEAT|__GFP_NOWARN,
			       HPT_ORDER - PAGE_SHIFT);
	if (!hpt) {
		pr_err("kvm_alloc_hpt: Couldn't alloc HPT\n");
		return -ENOMEM;
	}
	kvm->arch.hpt_virt = hpt;

	/* Allocate reverse map array */
	rev = vmalloc(sizeof(struct revmap_entry) * HPT_NPTE);
	if (!rev) {
		pr_err("kvmppc_alloc_hpt: Couldn't alloc reverse map array\n");
		goto out_freehpt;
	}
	kvm->arch.revmap = rev;

	/* Allocate the guest's logical partition ID */
	do {
		lpid = find_first_zero_bit(lpid_inuse, NR_LPIDS);
		if (lpid >= NR_LPIDS) {
			pr_err("kvm_alloc_hpt: No LPIDs free\n");
			goto out_freeboth;
		}
	} while (test_and_set_bit(lpid, lpid_inuse));

	kvm->arch.sdr1 = __pa(hpt) | (HPT_ORDER - 18);
	kvm->arch.lpid = lpid;

	pr_info("KVM guest htab at %lx, LPID %lx\n", hpt, lpid);
	return 0;

 out_freeboth:
	vfree(rev);
 out_freehpt:
	free_pages(hpt, HPT_ORDER - PAGE_SHIFT);
	return -ENOMEM;
}

void kvmppc_free_hpt(struct kvm *kvm)
{
	clear_bit(kvm->arch.lpid, lpid_inuse);
	vfree(kvm->arch.revmap);
	free_pages(kvm->arch.hpt_virt, HPT_ORDER - PAGE_SHIFT);
}

/* Bits in first HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte0_pgsize_encoding(unsigned long pgsize)
{
	return (pgsize > 0x1000) ? HPTE_V_LARGE : 0;
}

/* Bits in second HPTE dword for pagesize 4k, 64k or 16M */
static inline unsigned long hpte1_pgsize_encoding(unsigned long pgsize)
{
	return (pgsize == 0x10000) ? 0x1000 : 0;
}

void kvmppc_map_vrma(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
		     unsigned long porder)
{
	unsigned long i;
	unsigned long npages;
	unsigned long hp_v, hp_r;
	unsigned long addr, hash;
	unsigned long psize;
	unsigned long hp0, hp1;
	long ret;

	psize = 1ul << porder;
	npages = memslot->npages >> (porder - PAGE_SHIFT);

	/* VRMA can't be > 1TB */
	if (npages > 1ul << (40 - porder))
		npages = 1ul << (40 - porder);
	/* Can't use more than 1 HPTE per HPTEG */
	if (npages > HPT_NPTEG)
		npages = HPT_NPTEG;

	hp0 = HPTE_V_1TB_SEG | (VRMA_VSID << (40 - 16)) |
		HPTE_V_BOLTED | hpte0_pgsize_encoding(psize);
	hp1 = hpte1_pgsize_encoding(psize) |
		HPTE_R_R | HPTE_R_C | HPTE_R_M | PP_RWXX;

	for (i = 0; i < npages; ++i) {
		addr = i << porder;
		/* can't use hpt_hash since va > 64 bits */
		hash = (i ^ (VRMA_VSID ^ (VRMA_VSID << 25))) & HPT_HASH_MASK;
		/*
		 * We assume that the hash table is empty and no
		 * vcpus are using it at this stage.  Since we create
		 * at most one HPTE per HPTEG, we just assume entry 7
		 * is available and use it.
		 */
		hash = (hash << 3) + 7;
		hp_v = hp0 | ((addr >> 16) & ~0x7fUL);
		hp_r = hp1 | addr;
		ret = kvmppc_virtmode_h_enter(vcpu, H_EXACT, hash, hp_v, hp_r);
		if (ret != H_SUCCESS) {
			pr_err("KVM: map_vrma at %lx failed, ret=%ld\n",
			       addr, ret);
			break;
		}
	}
}

int kvmppc_mmu_hv_init(void)
{
	unsigned long host_lpid, rsvd_lpid;

	if (!cpu_has_feature(CPU_FTR_HVMODE))
		return -EINVAL;

	memset(lpid_inuse, 0, sizeof(lpid_inuse));

	if (cpu_has_feature(CPU_FTR_ARCH_206)) {
		host_lpid = mfspr(SPRN_LPID);	/* POWER7 */
		rsvd_lpid = LPID_RSVD;
	} else {
		host_lpid = 0;			/* PPC970 */
		rsvd_lpid = MAX_LPID_970;
	}

	set_bit(host_lpid, lpid_inuse);
	/* rsvd_lpid is reserved for use in partition switching */
	set_bit(rsvd_lpid, lpid_inuse);

	return 0;
}

void kvmppc_mmu_destroy(struct kvm_vcpu *vcpu)
{
}

static void kvmppc_mmu_book3s_64_hv_reset_msr(struct kvm_vcpu *vcpu)
{
	kvmppc_set_msr(vcpu, MSR_SF | MSR_ME);
}

/*
 * This is called to get a reference to a guest page if there isn't
 * one already in the kvm->arch.slot_phys[][] arrays.
 */
static long kvmppc_get_guest_page(struct kvm *kvm, unsigned long gfn,
				  struct kvm_memory_slot *memslot,
				  unsigned long psize)
{
	unsigned long start;
	long np, err;
	struct page *page, *hpage, *pages[1];
	unsigned long s, pgsize;
	unsigned long *physp;
	unsigned int is_io, got, pgorder;
	struct vm_area_struct *vma;
	unsigned long pfn, i, npages;

	physp = kvm->arch.slot_phys[memslot->id];
	if (!physp)
		return -EINVAL;
	if (physp[gfn - memslot->base_gfn])
		return 0;

	is_io = 0;
	got = 0;
	page = NULL;
	pgsize = psize;
	err = -EINVAL;
	start = gfn_to_hva_memslot(memslot, gfn);

	/* Instantiate and get the page we want access to */
	np = get_user_pages_fast(start, 1, 1, pages);
	if (np != 1) {
		/* Look up the vma for the page */
		down_read(&current->mm->mmap_sem);
		vma = find_vma(current->mm, start);
		if (!vma || vma->vm_start > start ||
		    start + psize > vma->vm_end ||
		    !(vma->vm_flags & VM_PFNMAP))
			goto up_err;
		is_io = hpte_cache_bits(pgprot_val(vma->vm_page_prot));
		pfn = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
		/* check alignment of pfn vs. requested page size */
		if (psize > PAGE_SIZE && (pfn & ((psize >> PAGE_SHIFT) - 1)))
			goto up_err;
		up_read(&current->mm->mmap_sem);

	} else {
		page = pages[0];
		got = KVMPPC_GOT_PAGE;

		/* See if this is a large page */
		s = PAGE_SIZE;
		if (PageHuge(page)) {
			hpage = compound_head(page);
			s <<= compound_order(hpage);
			/* Get the whole large page if slot alignment is ok */
			if (s > psize && slot_is_aligned(memslot, s) &&
			    !(memslot->userspace_addr & (s - 1))) {
				start &= ~(s - 1);
				pgsize = s;
				page = hpage;
			}
		}
		if (s < psize)
			goto out;
		pfn = page_to_pfn(page);
	}

	npages = pgsize >> PAGE_SHIFT;
	pgorder = __ilog2(npages);
	physp += (gfn - memslot->base_gfn) & ~(npages - 1);
	spin_lock(&kvm->arch.slot_phys_lock);
	for (i = 0; i < npages; ++i) {
		if (!physp[i]) {
			physp[i] = ((pfn + i) << PAGE_SHIFT) +
				got + is_io + pgorder;
			got = 0;
		}
	}
	spin_unlock(&kvm->arch.slot_phys_lock);
	err = 0;

 out:
	if (got) {
		if (PageHuge(page))
			page = compound_head(page);
		put_page(page);
	}
	return err;

 up_err:
	up_read(&current->mm->mmap_sem);
	return err;
}

/*
 * We come here on a H_ENTER call from the guest when
 * we don't have the requested page pinned already.
 */
long kvmppc_virtmode_h_enter(struct kvm_vcpu *vcpu, unsigned long flags,
			long pte_index, unsigned long pteh, unsigned long ptel)
{
	struct kvm *kvm = vcpu->kvm;
	unsigned long psize, gpa, gfn;
	struct kvm_memory_slot *memslot;
	long ret;

	psize = hpte_page_size(pteh, ptel);
	if (!psize)
		return H_PARAMETER;

	pteh &= ~(HPTE_V_HVLOCK | HPTE_V_ABSENT | HPTE_V_VALID);

	/* Find the memslot (if any) for this address */
	gpa = (ptel & HPTE_R_RPN) & ~(psize - 1);
	gfn = gpa >> PAGE_SHIFT;
	memslot = gfn_to_memslot(kvm, gfn);
	if (memslot && !(memslot->flags & KVM_MEMSLOT_INVALID)) {
		if (!slot_is_aligned(memslot, psize))
			return H_PARAMETER;
		if (kvmppc_get_guest_page(kvm, gfn, memslot, psize) < 0)
			return H_PARAMETER;
	}

	preempt_disable();
	ret = kvmppc_h_enter(vcpu, flags, pte_index, pteh, ptel);
	preempt_enable();
	if (ret == H_TOO_HARD) {
		/* this can't happen */
		pr_err("KVM: Oops, kvmppc_h_enter returned too hard!\n");
		ret = H_RESOURCE;	/* or something */
	}
	return ret;

}

static struct kvmppc_slb *kvmppc_mmu_book3s_hv_find_slbe(struct kvm_vcpu *vcpu,
							 gva_t eaddr)
{
	u64 mask;
	int i;

	for (i = 0; i < vcpu->arch.slb_nr; i++) {
		if (!(vcpu->arch.slb[i].orige & SLB_ESID_V))
			continue;

		if (vcpu->arch.slb[i].origv & SLB_VSID_B_1T)
			mask = ESID_MASK_1T;
		else
			mask = ESID_MASK;

		if (((vcpu->arch.slb[i].orige ^ eaddr) & mask) == 0)
			return &vcpu->arch.slb[i];
	}
	return NULL;
}

static unsigned long kvmppc_mmu_get_real_addr(unsigned long v, unsigned long r,
			unsigned long ea)
{
	unsigned long ra_mask;

	ra_mask = hpte_page_size(v, r) - 1;
	return (r & HPTE_R_RPN & ~ra_mask) | (ea & ra_mask);
}

static int kvmppc_mmu_book3s_64_hv_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
			struct kvmppc_pte *gpte, bool data)
{
	struct kvm *kvm = vcpu->kvm;
	struct kvmppc_slb *slbe;
	unsigned long slb_v;
	unsigned long pp, key;
	unsigned long v, gr;
	unsigned long *hptep;
	int index;
	int virtmode = vcpu->arch.shregs.msr & (data ? MSR_DR : MSR_IR);

	/* Get SLB entry */
	if (virtmode) {
		slbe = kvmppc_mmu_book3s_hv_find_slbe(vcpu, eaddr);
		if (!slbe)
			return -EINVAL;
		slb_v = slbe->origv;
	} else {
		/* real mode access */
		slb_v = vcpu->kvm->arch.vrma_slb_v;
	}

	/* Find the HPTE in the hash table */
	index = kvmppc_hv_find_lock_hpte(kvm, eaddr, slb_v,
					 HPTE_V_VALID | HPTE_V_ABSENT);
	if (index < 0)
		return -ENOENT;
	hptep = (unsigned long *)(kvm->arch.hpt_virt + (index << 4));
	v = hptep[0] & ~HPTE_V_HVLOCK;
	gr = kvm->arch.revmap[index].guest_rpte;

	/* Unlock the HPTE */
	asm volatile("lwsync" : : : "memory");
	hptep[0] = v;

	gpte->eaddr = eaddr;
	gpte->vpage = ((v & HPTE_V_AVPN) << 4) | ((eaddr >> 12) & 0xfff);

	/* Get PP bits and key for permission check */
	pp = gr & (HPTE_R_PP0 | HPTE_R_PP);
	key = (vcpu->arch.shregs.msr & MSR_PR) ? SLB_VSID_KP : SLB_VSID_KS;
	key &= slb_v;

	/* Calculate permissions */
	gpte->may_read = hpte_read_permission(pp, key);
	gpte->may_write = hpte_write_permission(pp, key);
	gpte->may_execute = gpte->may_read && !(gr & (HPTE_R_N | HPTE_R_G));

	/* Storage key permission check for POWER7 */
	if (data && virtmode && cpu_has_feature(CPU_FTR_ARCH_206)) {
		int amrfield = hpte_get_skey_perm(gr, vcpu->arch.amr);
		if (amrfield & 1)
			gpte->may_read = 0;
		if (amrfield & 2)
			gpte->may_write = 0;
	}

	/* Get the guest physical address */
	gpte->raddr = kvmppc_mmu_get_real_addr(v, gr, eaddr);
	return 0;
}

/*
 * Quick test for whether an instruction is a load or a store.
 * If the instruction is a load or a store, then this will indicate
 * which it is, at least on server processors.  (Embedded processors
 * have some external PID instructions that don't follow the rule
 * embodied here.)  If the instruction isn't a load or store, then
 * this doesn't return anything useful.
 */
static int instruction_is_store(unsigned int instr)
{
	unsigned int mask;

	mask = 0x10000000;
	if ((instr & 0xfc000000) == 0x7c000000)
		mask = 0x100;		/* major opcode 31 */
	return (instr & mask) != 0;
}

static int kvmppc_hv_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu,
				  unsigned long gpa, int is_store)
{
	int ret;
	u32 last_inst;
	unsigned long srr0 = kvmppc_get_pc(vcpu);

	/* We try to load the last instruction.  We don't let
	 * emulate_instruction do it as it doesn't check what
	 * kvmppc_ld returns.
	 * If we fail, we just return to the guest and try executing it again.
	 */
	if (vcpu->arch.last_inst == KVM_INST_FETCH_FAILED) {
		ret = kvmppc_ld(vcpu, &srr0, sizeof(u32), &last_inst, false);
		if (ret != EMULATE_DONE || last_inst == KVM_INST_FETCH_FAILED)
			return RESUME_GUEST;
		vcpu->arch.last_inst = last_inst;
	}

	/*
	 * WARNING: We do not know for sure whether the instruction we just
	 * read from memory is the same that caused the fault in the first
	 * place.  If the instruction we read is neither an load or a store,
	 * then it can't access memory, so we don't need to worry about
	 * enforcing access permissions.  So, assuming it is a load or
	 * store, we just check that its direction (load or store) is
	 * consistent with the original fault, since that's what we
	 * checked the access permissions against.  If there is a mismatch
	 * we just return and retry the instruction.
	 */

	if (instruction_is_store(vcpu->arch.last_inst) != !!is_store)
		return RESUME_GUEST;

	/*
	 * Emulated accesses are emulated by looking at the hash for
	 * translation once, then performing the access later. The
	 * translation could be invalidated in the meantime in which
	 * point performing the subsequent memory access on the old
	 * physical address could possibly be a security hole for the
	 * guest (but not the host).
	 *
	 * This is less of an issue for MMIO stores since they aren't
	 * globally visible. It could be an issue for MMIO loads to
	 * a certain extent but we'll ignore it for now.
	 */

	vcpu->arch.paddr_accessed = gpa;
	return kvmppc_emulate_mmio(run, vcpu);
}

int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
				unsigned long ea, unsigned long dsisr)
{
	struct kvm *kvm = vcpu->kvm;
	unsigned long *hptep, hpte[3];
	unsigned long psize;
	unsigned long gfn;
	struct kvm_memory_slot *memslot;
	struct revmap_entry *rev;
	long index;

	/*
	 * Real-mode code has already searched the HPT and found the
	 * entry we're interested in.  Lock the entry and check that
	 * it hasn't changed.  If it has, just return and re-execute the
	 * instruction.
	 */
	if (ea != vcpu->arch.pgfault_addr)
		return RESUME_GUEST;
	index = vcpu->arch.pgfault_index;
	hptep = (unsigned long *)(kvm->arch.hpt_virt + (index << 4));
	rev = &kvm->arch.revmap[index];
	preempt_disable();
	while (!try_lock_hpte(hptep, HPTE_V_HVLOCK))
		cpu_relax();
	hpte[0] = hptep[0] & ~HPTE_V_HVLOCK;
	hpte[1] = hptep[1];
	hpte[2] = rev->guest_rpte;
	asm volatile("lwsync" : : : "memory");
	hptep[0] = hpte[0];
	preempt_enable();

	if (hpte[0] != vcpu->arch.pgfault_hpte[0] ||
	    hpte[1] != vcpu->arch.pgfault_hpte[1])
		return RESUME_GUEST;

	/* Translate the logical address and get the page */
	psize = hpte_page_size(hpte[0], hpte[1]);
	gfn = hpte_rpn(hpte[2], psize);
	memslot = gfn_to_memslot(kvm, gfn);

	/* No memslot means it's an emulated MMIO region */
	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID)) {
		unsigned long gpa = (gfn << PAGE_SHIFT) | (ea & (psize - 1));
		return kvmppc_hv_emulate_mmio(run, vcpu, gpa,
					      dsisr & DSISR_ISSTORE);
	}

	/* should never get here otherwise */
	return -EFAULT;
}

void *kvmppc_pin_guest_page(struct kvm *kvm, unsigned long gpa,
			    unsigned long *nb_ret)
{
	struct kvm_memory_slot *memslot;
	unsigned long gfn = gpa >> PAGE_SHIFT;
	struct page *page;
	unsigned long psize, offset;
	unsigned long pa;
	unsigned long *physp;

	memslot = gfn_to_memslot(kvm, gfn);
	if (!memslot || (memslot->flags & KVM_MEMSLOT_INVALID))
		return NULL;
	physp = kvm->arch.slot_phys[memslot->id];
	if (!physp)
		return NULL;
	physp += gfn - memslot->base_gfn;
	pa = *physp;
	if (!pa) {
		if (kvmppc_get_guest_page(kvm, gfn, memslot, PAGE_SIZE) < 0)
			return NULL;
		pa = *physp;
	}
	page = pfn_to_page(pa >> PAGE_SHIFT);
	psize = PAGE_SIZE;
	if (PageHuge(page)) {
		page = compound_head(page);
		psize <<= compound_order(page);
	}
	get_page(page);
	offset = gpa & (psize - 1);
	if (nb_ret)
		*nb_ret = psize - offset;
	return page_address(page) + offset;
}

void kvmppc_unpin_guest_page(struct kvm *kvm, void *va)
{
	struct page *page = virt_to_page(va);

	page = compound_head(page);
	put_page(page);
}

void kvmppc_mmu_book3s_hv_init(struct kvm_vcpu *vcpu)
{
	struct kvmppc_mmu *mmu = &vcpu->arch.mmu;

	if (cpu_has_feature(CPU_FTR_ARCH_206))
		vcpu->arch.slb_nr = 32;		/* POWER7 */
	else
		vcpu->arch.slb_nr = 64;

	mmu->xlate = kvmppc_mmu_book3s_64_hv_xlate;
	mmu->reset_msr = kvmppc_mmu_book3s_64_hv_reset_msr;

	vcpu->arch.hflags |= BOOK3S_HFLAG_SLB;
}