pt_element_t pte;
pt_element_t __user *uninitialized_var(ptep_user);
gfn_t table_gfn;
- unsigned index, pt_access, pte_access, accessed_dirty, shift;
+ unsigned index, pt_access, pte_access, accessed_dirty;
gpa_t pte_gpa;
int offset;
const int write_fault = access & PFERR_WRITE_MASK;
if (!write_fault)
protect_clean_gpte(&pte_access, pte);
-
- /*
- * On a write fault, fold the dirty bit into accessed_dirty by shifting it one
- * place right.
- *
- * On a read fault, do nothing.
- */
- shift = write_fault >> ilog2(PFERR_WRITE_MASK);
- shift *= PT_DIRTY_SHIFT - PT_ACCESSED_SHIFT;
- accessed_dirty &= pte >> shift;
+ else
+ /*
+ * On a write fault, fold the dirty bit into accessed_dirty by
+ * shifting it one place right.
+ */
+ accessed_dirty &= pte >> (PT_DIRTY_SHIFT - PT_ACCESSED_SHIFT);
if (unlikely(!accessed_dirty)) {
ret = FNAME(update_accessed_dirty_bits)(vcpu, mmu, walker, write_fault);
addr, access);
}
-static bool FNAME(prefetch_invalid_gpte)(struct kvm_vcpu *vcpu,
- struct kvm_mmu_page *sp, u64 *spte,
- pt_element_t gpte)
+static bool
+FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+ u64 *spte, pt_element_t gpte, bool no_dirty_log)
{
- if (is_rsvd_bits_set(&vcpu->arch.mmu, gpte, PT_PAGE_TABLE_LEVEL))
- goto no_present;
+ unsigned pte_access;
+ gfn_t gfn;
+ pfn_t pfn;
- if (!is_present_gpte(gpte))
- goto no_present;
+ if (prefetch_invalid_gpte(vcpu, sp, spte, gpte))
+ return false;
- if (!(gpte & PT_ACCESSED_MASK))
- goto no_present;
+ pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
- return false;
+ gfn = gpte_to_gfn(gpte);
+ pte_access = sp->role.access & gpte_access(vcpu, gpte);
+ protect_clean_gpte(&pte_access, gpte);
+ pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
+ no_dirty_log && (pte_access & ACC_WRITE_MASK));
+ if (is_error_pfn(pfn))
+ return false;
+
+ /*
+ * we call mmu_set_spte() with host_writable = true because
+ * pte_prefetch_gfn_to_pfn always gets a writable pfn.
+ */
+ mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0,
+ NULL, PT_PAGE_TABLE_LEVEL, gfn, pfn, true, true);
-no_present:
- drop_spte(vcpu->kvm, spte);
return true;
}
static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
u64 *spte, const void *pte)
{
- pt_element_t gpte;
- unsigned pte_access;
- pfn_t pfn;
-
- gpte = *(const pt_element_t *)pte;
- if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
- return;
+ pt_element_t gpte = *(const pt_element_t *)pte;
- pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
- pte_access = sp->role.access & gpte_access(vcpu, gpte);
- protect_clean_gpte(&pte_access, gpte);
- pfn = gfn_to_pfn_atomic(vcpu->kvm, gpte_to_gfn(gpte));
- if (mmu_invalid_pfn(pfn))
- return;
-
- /*
- * we call mmu_set_spte() with host_writable = true because that
- * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
- */
- mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
- NULL, PT_PAGE_TABLE_LEVEL,
- gpte_to_gfn(gpte), pfn, true, true);
+ FNAME(prefetch_gpte)(vcpu, sp, spte, gpte, false);
}
static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
spte = sp->spt + i;
for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
- pt_element_t gpte;
- unsigned pte_access;
- gfn_t gfn;
- pfn_t pfn;
-
if (spte == sptep)
continue;
if (is_shadow_present_pte(*spte))
continue;
- gpte = gptep[i];
-
- if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
- continue;
-
- pte_access = sp->role.access & gpte_access(vcpu, gpte);
- protect_clean_gpte(&pte_access, gpte);
- gfn = gpte_to_gfn(gpte);
- pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
- pte_access & ACC_WRITE_MASK);
- if (mmu_invalid_pfn(pfn))
+ if (!FNAME(prefetch_gpte)(vcpu, sp, spte, gptep[i], true))
break;
-
- mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
- NULL, PT_PAGE_TABLE_LEVEL, gfn,
- pfn, true, true);
}
}
/*
* Fetch a shadow pte for a specific level in the paging hierarchy.
+ * If the guest tries to write a write-protected page, we need to
+ * emulate this operation, return 1 to indicate this case.
*/
-static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
+static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
struct guest_walker *gw,
- int user_fault, int write_fault, int hlevel,
- int *emulate, pfn_t pfn, bool map_writable,
- bool prefault)
+ int write_fault, int hlevel,
+ pfn_t pfn, bool map_writable, bool prefault)
{
- unsigned access = gw->pt_access;
struct kvm_mmu_page *sp = NULL;
- int top_level;
- unsigned direct_access;
struct kvm_shadow_walk_iterator it;
+ unsigned direct_access, access = gw->pt_access;
+ int top_level, emulate = 0;
if (!is_present_gpte(gw->ptes[gw->level - 1]))
- return NULL;
+ return 0;
direct_access = gw->pte_access;
clear_sp_write_flooding_count(it.sptep);
mmu_set_spte(vcpu, it.sptep, access, gw->pte_access,
- user_fault, write_fault, emulate, it.level,
+ write_fault, &emulate, it.level,
gw->gfn, pfn, prefault, map_writable);
FNAME(pte_prefetch)(vcpu, gw, it.sptep);
- return it.sptep;
+ return emulate;
out_gpte_changed:
if (sp)
kvm_mmu_put_page(sp, it.sptep);
kvm_release_pfn_clean(pfn);
- return NULL;
+ return 0;
+}
+
+ /*
+ * To see whether the mapped gfn can write its page table in the current
+ * mapping.
+ *
+ * It is the helper function of FNAME(page_fault). When guest uses large page
+ * size to map the writable gfn which is used as current page table, we should
+ * force kvm to use small page size to map it because new shadow page will be
+ * created when kvm establishes shadow page table that stop kvm using large
+ * page size. Do it early can avoid unnecessary #PF and emulation.
+ *
+ * Note: the PDPT page table is not checked for PAE-32 bit guest. It is ok
+ * since the PDPT is always shadowed, that means, we can not use large page
+ * size to map the gfn which is used as PDPT.
+ */
+static bool
+FNAME(is_self_change_mapping)(struct kvm_vcpu *vcpu,
+ struct guest_walker *walker, int user_fault)
+{
+ int level;
+ gfn_t mask = ~(KVM_PAGES_PER_HPAGE(walker->level) - 1);
+
+ if (!(walker->pte_access & ACC_WRITE_MASK ||
+ (!is_write_protection(vcpu) && !user_fault)))
+ return false;
+
+ for (level = walker->level; level <= walker->max_level; level++)
+ if (!((walker->gfn ^ walker->table_gfn[level - 1]) & mask))
+ return true;
+
+ return false;
}
/*
int write_fault = error_code & PFERR_WRITE_MASK;
int user_fault = error_code & PFERR_USER_MASK;
struct guest_walker walker;
- u64 *sptep;
- int emulate = 0;
int r;
pfn_t pfn;
int level = PT_PAGE_TABLE_LEVEL;
}
if (walker.level >= PT_DIRECTORY_LEVEL)
- force_pt_level = mapping_level_dirty_bitmap(vcpu, walker.gfn);
+ force_pt_level = mapping_level_dirty_bitmap(vcpu, walker.gfn)
+ || FNAME(is_self_change_mapping)(vcpu, &walker, user_fault);
else
force_pt_level = 1;
if (!force_pt_level) {
walker.gfn, pfn, walker.pte_access, &r))
return r;
+ /*
+ * Do not change pte_access if the pfn is a mmio page, otherwise
+ * we will cache the incorrect access into mmio spte.
+ */
+ if (write_fault && !(walker.pte_access & ACC_WRITE_MASK) &&
+ !is_write_protection(vcpu) && !user_fault &&
+ !is_noslot_pfn(pfn)) {
+ walker.pte_access |= ACC_WRITE_MASK;
+ walker.pte_access &= ~ACC_USER_MASK;
+
+ /*
+ * If we converted a user page to a kernel page,
+ * so that the kernel can write to it when cr0.wp=0,
+ * then we should prevent the kernel from executing it
+ * if SMEP is enabled.
+ */
+ if (kvm_read_cr4_bits(vcpu, X86_CR4_SMEP))
+ walker.pte_access &= ~ACC_EXEC_MASK;
+ }
+
spin_lock(&vcpu->kvm->mmu_lock);
- if (mmu_notifier_retry(vcpu, mmu_seq))
+ if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
goto out_unlock;
kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);
kvm_mmu_free_some_pages(vcpu);
if (!force_pt_level)
transparent_hugepage_adjust(vcpu, &walker.gfn, &pfn, &level);
- sptep = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault,
- level, &emulate, pfn, map_writable, prefault);
- (void)sptep;
- pgprintk("%s: shadow pte %p %llx emulate %d\n", __func__,
- sptep, *sptep, emulate);
-
+ r = FNAME(fetch)(vcpu, addr, &walker, write_fault,
+ level, pfn, map_writable, prefault);
++vcpu->stat.pf_fixed;
kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
spin_unlock(&vcpu->kvm->mmu_lock);
- return emulate;
+ return r;
out_unlock:
spin_unlock(&vcpu->kvm->mmu_lock);
sizeof(pt_element_t)))
return -EINVAL;
- if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) {
+ if (prefetch_invalid_gpte(vcpu, sp, &sp->spt[i], gpte)) {
vcpu->kvm->tlbs_dirty++;
continue;
}
host_writable = sp->spt[i] & SPTE_HOST_WRITEABLE;
- set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
+ set_spte(vcpu, &sp->spt[i], pte_access,
PT_PAGE_TABLE_LEVEL, gfn,
spte_to_pfn(sp->spt[i]), true, false,
host_writable);
projects / deliverable / linux.git / blobdiff