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aba8592950
linux/arch/mips/kvm/mmu.c
James Hogan aba8592950 KVM: MIPS/MMU: Invalidate stale GVA PTEs on TLBW 
Implement invalidation of specific pairs of GVA page table entries in
one or both of the GVA page tables. This is used when existing mappings
are replaced in the guest TLB by emulated TLBWI/TLBWR instructions. Due
to the sharing of page tables in the host kernel range, we should be
careful not to allow host pages to be invalidated.

Add a helper kvm_mips_walk_pgd() which can be used when walking of
either GPA (future patches) or GVA page tables is needed, optionally
with allocation of page tables along the way when they don't exist.

GPA page table walking will need to be protected by the kvm->mmu_lock,
so we also add a small MMU page cache in each KVM VCPU, like that found
for other architectures but smaller. This allows enough pages to be
pre-allocated to handle a single fault without holding the lock,
allowing the helper to run with the lock held without having to handle
allocation failures.

Using the same mechanism for GVA allows the same code to be used, and
allows it to use the same cache of allocated pages if the GPA walk
didn't need to allocate any new tables.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: "Radim Krčmář" <rkrcmar@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
2017-02-03 15:20:56 +00:00

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/*
* 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>
#include <asm/pgalloc.h>
static void mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
{
while (mc->nobjs)
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
static void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
{
void *p;
BUG_ON(!mc || !mc->nobjs);
p = mc->objects[--mc->nobjs];
return p;
}
void kvm_mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
mmu_free_memory_cache(&vcpu->arch.mmu_page_cache);
}
static u32 kvm_mips_get_kernel_asid(struct kvm_vcpu *vcpu)
{
struct mm_struct *kern_mm = &vcpu->arch.guest_kernel_mm;
int cpu = smp_processor_id();
return cpu_asid(cpu, kern_mm);
}
static u32 kvm_mips_get_user_asid(struct kvm_vcpu *vcpu)
{
struct mm_struct *user_mm = &vcpu->arch.guest_user_mm;
int cpu = smp_processor_id();
return cpu_asid(cpu, user_mm);
}
/**
* kvm_mips_walk_pgd() - Walk page table with optional allocation.
* @pgd: Page directory pointer.
* @addr: Address to index page table using.
* @cache: MMU page cache to allocate new page tables from, or NULL.
*
* Walk the page tables pointed to by @pgd to find the PTE corresponding to the
* address @addr. If page tables don't exist for @addr, they will be created
* from the MMU cache if @cache is not NULL.
*
* Returns: Pointer to pte_t corresponding to @addr.
* NULL if a page table doesn't exist for @addr and !@cache.
* NULL if a page table allocation failed.
*/
static pte_t *kvm_mips_walk_pgd(pgd_t *pgd, struct kvm_mmu_memory_cache *cache,
unsigned long addr)
{
pud_t *pud;
pmd_t *pmd;
pgd += pgd_index(addr);
if (pgd_none(*pgd)) {
/* Not used on MIPS yet */
BUG();
return NULL;
}
pud = pud_offset(pgd, addr);
if (pud_none(*pud)) {
pmd_t *new_pmd;
if (!cache)
return NULL;
new_pmd = mmu_memory_cache_alloc(cache);
pmd_init((unsigned long)new_pmd,
(unsigned long)invalid_pte_table);
pud_populate(NULL, pud, new_pmd);
}
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd)) {
pte_t *new_pte;
if (!cache)
return NULL;
new_pte = mmu_memory_cache_alloc(cache);
clear_page(new_pte);
pmd_populate_kernel(NULL, pmd, new_pte);
}
return pte_offset(pmd, addr);
}
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_noslot_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;
}
void kvm_trap_emul_invalidate_gva(struct kvm_vcpu *vcpu, unsigned long addr,
bool user)
{
pgd_t *pgdp;
pte_t *ptep;
addr &= PAGE_MASK << 1;
pgdp = vcpu->arch.guest_kernel_mm.pgd;
ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
if (ptep) {
ptep[0] = pfn_pte(0, __pgprot(0));
ptep[1] = pfn_pte(0, __pgprot(0));
}
if (user) {
pgdp = vcpu->arch.guest_user_mm.pgd;
ptep = kvm_mips_walk_pgd(pgdp, NULL, addr);
if (ptep) {
ptep[0] = pfn_pte(0, __pgprot(0));
ptep[1] = pfn_pte(0, __pgprot(0));
}
}
}
/*
* kvm_mips_flush_gva_{pte,pmd,pud,pgd,pt}.
* Flush a range of guest physical address space from the VM's GPA page tables.
*/
static bool kvm_mips_flush_gva_pte(pte_t *pte, unsigned long start_gva,
unsigned long end_gva)
{
int i_min = __pte_offset(start_gva);
int i_max = __pte_offset(end_gva);
bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PTE - 1);
int i;
/*
* There's no freeing to do, so there's no point clearing individual
* entries unless only part of the last level page table needs flushing.
*/
if (safe_to_remove)
return true;
for (i = i_min; i <= i_max; ++i) {
if (!pte_present(pte[i]))
continue;
set_pte(pte + i, __pte(0));
}
return false;
}
static bool kvm_mips_flush_gva_pmd(pmd_t *pmd, unsigned long start_gva,
unsigned long end_gva)
{
pte_t *pte;
unsigned long end = ~0ul;
int i_min = __pmd_offset(start_gva);
int i_max = __pmd_offset(end_gva);
bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PMD - 1);
int i;
for (i = i_min; i <= i_max; ++i, start_gva = 0) {
if (!pmd_present(pmd[i]))
continue;
pte = pte_offset(pmd + i, 0);
if (i == i_max)
end = end_gva;
if (kvm_mips_flush_gva_pte(pte, start_gva, end)) {
pmd_clear(pmd + i);
pte_free_kernel(NULL, pte);
} else {
safe_to_remove = false;
}
}
return safe_to_remove;
}
static bool kvm_mips_flush_gva_pud(pud_t *pud, unsigned long start_gva,
unsigned long end_gva)
{
pmd_t *pmd;
unsigned long end = ~0ul;
int i_min = __pud_offset(start_gva);
int i_max = __pud_offset(end_gva);
bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PUD - 1);
int i;
for (i = i_min; i <= i_max; ++i, start_gva = 0) {
if (!pud_present(pud[i]))
continue;
pmd = pmd_offset(pud + i, 0);
if (i == i_max)
end = end_gva;
if (kvm_mips_flush_gva_pmd(pmd, start_gva, end)) {
pud_clear(pud + i);
pmd_free(NULL, pmd);
} else {
safe_to_remove = false;
}
}
return safe_to_remove;
}
static bool kvm_mips_flush_gva_pgd(pgd_t *pgd, unsigned long start_gva,
unsigned long end_gva)
{
pud_t *pud;
unsigned long end = ~0ul;
int i_min = pgd_index(start_gva);
int i_max = pgd_index(end_gva);
bool safe_to_remove = (i_min == 0 && i_max == PTRS_PER_PGD - 1);
int i;
for (i = i_min; i <= i_max; ++i, start_gva = 0) {
if (!pgd_present(pgd[i]))
continue;
pud = pud_offset(pgd + i, 0);
if (i == i_max)
end = end_gva;
if (kvm_mips_flush_gva_pud(pud, start_gva, end)) {
pgd_clear(pgd + i);
pud_free(NULL, pud);
} else {
safe_to_remove = false;
}
}
return safe_to_remove;
}
void kvm_mips_flush_gva_pt(pgd_t *pgd, enum kvm_mips_flush flags)
{
if (flags & KMF_GPA) {
/* all of guest virtual address space could be affected */
if (flags & KMF_KERN)
/* useg, kseg0, seg2/3 */
kvm_mips_flush_gva_pgd(pgd, 0, 0x7fffffff);
else
/* useg */
kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
} else {
/* useg */
kvm_mips_flush_gva_pgd(pgd, 0, 0x3fffffff);
/* kseg2/3 */
if (flags & KMF_KERN)
kvm_mips_flush_gva_pgd(pgd, 0x60000000, 0x7fffffff);
}
}
/* 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 | 1) >= 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;
gfn_t gfn0, gfn1;
long tlb_lo[2];
int ret;
tlb_lo[0] = tlb->tlb_lo[0];
tlb_lo[1] = tlb->tlb_lo[1];
/*
* The commpage address must not be mapped to anything else if the guest
* TLB contains entries nearby, or commpage accesses will break.
*/
if (!((tlb->tlb_hi ^ KVM_GUEST_COMMPAGE_ADDR) &
VPN2_MASK & (PAGE_MASK << 1)))
tlb_lo[(KVM_GUEST_COMMPAGE_ADDR >> PAGE_SHIFT) & 1] = 0;
gfn0 = mips3_tlbpfn_to_paddr(tlb_lo[0]) >> PAGE_SHIFT;
gfn1 = mips3_tlbpfn_to_paddr(tlb_lo[1]) >> PAGE_SHIFT;
if (gfn0 >= kvm->arch.guest_pmap_npages ||
gfn1 >= kvm->arch.guest_pmap_npages) {
kvm_err("%s: Invalid gfn: [%#llx, %#llx], EHi: %#lx\n",
__func__, gfn0, gfn1, tlb->tlb_hi);
kvm_mips_dump_guest_tlbs(vcpu);
return -1;
}
if (kvm_mips_map_page(kvm, gfn0) < 0)
return -1;
if (kvm_mips_map_page(kvm, gfn1) < 0)
return -1;
pfn0 = kvm->arch.guest_pmap[gfn0];
pfn1 = kvm->arch.guest_pmap[gfn1];
/* Get attributes from the Guest TLB */
entrylo0 = mips3_paddr_to_tlbpfn(pfn0 << PAGE_SHIFT) |
((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
(tlb_lo[0] & ENTRYLO_D) |
(tlb_lo[0] & ENTRYLO_V);
entrylo1 = mips3_paddr_to_tlbpfn(pfn1 << PAGE_SHIFT) |
((_page_cachable_default >> _CACHE_SHIFT) << ENTRYLO_C_SHIFT) |
(tlb_lo[1] & ENTRYLO_D) |
(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 flags;
kvm_debug("%s: vcpu %p, cpu: %d\n", __func__, vcpu, cpu);
local_irq_save(flags);
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);
}
/* restore guest state to registers */
kvm_mips_callbacks->vcpu_load(vcpu, cpu);
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.last_sched_cpu = cpu;
/* save guest state in registers */
kvm_mips_callbacks->vcpu_put(vcpu, cpu);
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;
}
if (kvm_mips_handle_mapped_seg_tlb_fault(vcpu,
&vcpu->arch.guest_tlb[index])) {
kvm_err("%s: handling mapped seg tlb fault failed for %p, index: %u, vcpu: %p, ASID: %#lx\n",
__func__, opc, index, vcpu,
read_c0_entryhi());
kvm_mips_dump_guest_tlbs(vcpu);
local_irq_restore(flags);
return KVM_INVALID_INST;
}
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;
}
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