mirror of https://gitee.com/openkylin/linux.git
KVM: MMU: Simplify page table walker
Simplify the walker level loop not to carry so much information from one loop to the next. In addition to being complex, this made kmap_atomic() critical sections difficult to manage. As a result of this change, kmap_atomic() sections are limited to actually touching the guest pte, which allows the other functions called from the walker to do sleepy operations. This will happen when we enable swapping. Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Avi Kivity
parent
d77a25074a
commit
42bf3f0a1f
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@ -59,32 +59,12 @@
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struct guest_walker {
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int level;
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gfn_t table_gfn[PT_MAX_FULL_LEVELS];
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pt_element_t *table;
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pt_element_t pte;
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pt_element_t *ptep;
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struct page *page;
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int index;
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pt_element_t inherited_ar;
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gfn_t gfn;
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u32 error_code;
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};
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static void FNAME(update_dirty_bit)(struct kvm_vcpu *vcpu,
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int write_fault,
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pt_element_t *ptep,
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gfn_t table_gfn)
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{
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gpa_t pte_gpa;
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if (write_fault && !is_dirty_pte(*ptep)) {
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mark_page_dirty(vcpu->kvm, table_gfn);
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*ptep |= PT_DIRTY_MASK;
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pte_gpa = ((gpa_t)table_gfn << PAGE_SHIFT);
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pte_gpa += offset_in_page(ptep);
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kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)ptep, sizeof(*ptep));
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}
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}
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/*
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* Fetch a guest pte for a guest virtual address
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*/
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@ -94,105 +74,99 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
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{
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hpa_t hpa;
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struct kvm_memory_slot *slot;
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pt_element_t *ptep;
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pt_element_t root;
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struct page *page;
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pt_element_t *table;
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pt_element_t pte;
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gfn_t table_gfn;
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unsigned index;
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gpa_t pte_gpa;
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pgprintk("%s: addr %lx\n", __FUNCTION__, addr);
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walker->level = vcpu->mmu.root_level;
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walker->table = NULL;
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walker->page = NULL;
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walker->ptep = NULL;
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root = vcpu->cr3;
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pte = vcpu->cr3;
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#if PTTYPE == 64
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if (!is_long_mode(vcpu)) {
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walker->ptep = &vcpu->pdptrs[(addr >> 30) & 3];
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root = *walker->ptep;
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walker->pte = root;
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if (!(root & PT_PRESENT_MASK))
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pte = vcpu->pdptrs[(addr >> 30) & 3];
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if (!is_present_pte(pte))
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goto not_present;
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--walker->level;
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}
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#endif
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table_gfn = (root & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
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walker->table_gfn[walker->level - 1] = table_gfn;
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pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
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walker->level - 1, table_gfn);
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slot = gfn_to_memslot(vcpu->kvm, table_gfn);
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hpa = safe_gpa_to_hpa(vcpu->kvm, root & PT64_BASE_ADDR_MASK);
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walker->page = pfn_to_page(hpa >> PAGE_SHIFT);
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walker->table = kmap_atomic(walker->page, KM_USER0);
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ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
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(vcpu->cr3 & CR3_NONPAE_RESERVED_BITS) == 0);
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walker->inherited_ar = PT_USER_MASK | PT_WRITABLE_MASK;
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for (;;) {
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int index = PT_INDEX(addr, walker->level);
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hpa_t paddr;
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index = PT_INDEX(addr, walker->level);
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ptep = &walker->table[index];
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walker->index = index;
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ASSERT(((unsigned long)walker->table & PAGE_MASK) ==
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((unsigned long)ptep & PAGE_MASK));
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table_gfn = (pte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
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walker->table_gfn[walker->level - 1] = table_gfn;
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pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
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walker->level - 1, table_gfn);
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if (!is_present_pte(*ptep))
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slot = gfn_to_memslot(vcpu->kvm, table_gfn);
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hpa = safe_gpa_to_hpa(vcpu->kvm, pte & PT64_BASE_ADDR_MASK);
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page = pfn_to_page(hpa >> PAGE_SHIFT);
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table = kmap_atomic(page, KM_USER0);
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pte = table[index];
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kunmap_atomic(table, KM_USER0);
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if (!is_present_pte(pte))
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goto not_present;
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if (write_fault && !is_writeble_pte(*ptep))
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if (write_fault && !is_writeble_pte(pte))
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if (user_fault || is_write_protection(vcpu))
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goto access_error;
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if (user_fault && !(*ptep & PT_USER_MASK))
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if (user_fault && !(pte & PT_USER_MASK))
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goto access_error;
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#if PTTYPE == 64
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if (fetch_fault && is_nx(vcpu) && (*ptep & PT64_NX_MASK))
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if (fetch_fault && is_nx(vcpu) && (pte & PT64_NX_MASK))
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goto access_error;
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#endif
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if (!(*ptep & PT_ACCESSED_MASK)) {
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if (!(pte & PT_ACCESSED_MASK)) {
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mark_page_dirty(vcpu->kvm, table_gfn);
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*ptep |= PT_ACCESSED_MASK;
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pte |= PT_ACCESSED_MASK;
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table = kmap_atomic(page, KM_USER0);
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table[index] = pte;
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kunmap_atomic(table, KM_USER0);
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}
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if (walker->level == PT_PAGE_TABLE_LEVEL) {
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walker->gfn = (*ptep & PT_BASE_ADDR_MASK)
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>> PAGE_SHIFT;
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FNAME(update_dirty_bit)(vcpu, write_fault, ptep,
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table_gfn);
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walker->gfn = (pte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
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break;
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}
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if (walker->level == PT_DIRECTORY_LEVEL
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&& (*ptep & PT_PAGE_SIZE_MASK)
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&& (pte & PT_PAGE_SIZE_MASK)
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&& (PTTYPE == 64 || is_pse(vcpu))) {
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walker->gfn = (*ptep & PT_DIR_BASE_ADDR_MASK)
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walker->gfn = (pte & PT_DIR_BASE_ADDR_MASK)
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>> PAGE_SHIFT;
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walker->gfn += PT_INDEX(addr, PT_PAGE_TABLE_LEVEL);
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FNAME(update_dirty_bit)(vcpu, write_fault, ptep,
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table_gfn);
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break;
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}
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walker->inherited_ar &= walker->table[index];
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table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT;
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kunmap_atomic(walker->table, KM_USER0);
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paddr = safe_gpa_to_hpa(vcpu->kvm, table_gfn << PAGE_SHIFT);
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walker->page = pfn_to_page(paddr >> PAGE_SHIFT);
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walker->table = kmap_atomic(walker->page, KM_USER0);
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walker->inherited_ar &= pte;
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--walker->level;
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walker->table_gfn[walker->level - 1] = table_gfn;
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pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
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walker->level - 1, table_gfn);
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}
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walker->pte = *ptep;
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if (walker->page)
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walker->ptep = NULL;
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if (walker->table)
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kunmap_atomic(walker->table, KM_USER0);
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pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)*ptep);
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if (write_fault && !is_dirty_pte(pte)) {
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mark_page_dirty(vcpu->kvm, table_gfn);
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pte |= PT_DIRTY_MASK;
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table = kmap_atomic(page, KM_USER0);
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table[index] = pte;
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kunmap_atomic(table, KM_USER0);
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pte_gpa = table_gfn << PAGE_SHIFT;
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pte_gpa += index * sizeof(pt_element_t);
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kvm_mmu_pte_write(vcpu, pte_gpa, (u8 *)&pte, sizeof(pte));
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}
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walker->pte = pte;
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pgprintk("%s: pte %llx\n", __FUNCTION__, (u64)pte);
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return 1;
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not_present:
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@ -209,8 +183,6 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
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walker->error_code |= PFERR_USER_MASK;
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if (fetch_fault)
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walker->error_code |= PFERR_FETCH_MASK;
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if (walker->table)
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kunmap_atomic(walker->table, KM_USER0);
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return 0;
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}
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