From 97a0a01ea9229e4f3f0f06e0584227e9687159a5 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 31 May 2007 15:08:29 +0300 Subject: [PATCH] KVM: MMU: Fold fix_write_pf() into set_pte_common() This prevents some work from being performed twice, and, more importantly, reduces the number of places where we modify shadow ptes. Signed-off-by: Avi Kivity --- drivers/kvm/mmu.c | 11 +++ drivers/kvm/paging_tmpl.h | 168 +++++++++++++------------------------- 2 files changed, 68 insertions(+), 111 deletions(-) diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 2079d69f186a..3cdbf687df25 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -731,6 +731,17 @@ static int kvm_mmu_unprotect_page(struct kvm_vcpu *vcpu, gfn_t gfn) return r; } +static void mmu_unshadow(struct kvm_vcpu *vcpu, gfn_t gfn) +{ + struct kvm_mmu_page *page; + + while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) { + pgprintk("%s: zap %lx %x\n", + __FUNCTION__, gfn, page->role.word); + kvm_mmu_zap_page(vcpu, page); + } +} + static void page_header_update_slot(struct kvm *kvm, void *pte, gpa_t gpa) { int slot = memslot_id(kvm, gfn_to_memslot(kvm, gpa >> PAGE_SHIFT)); diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index 869582befaf1..c06720385551 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -197,11 +197,26 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, gpa_t gaddr, pt_element_t *gpte, u64 access_bits, + int user_fault, int write_fault, + int *ptwrite, + struct guest_walker *walker, gfn_t gfn) { hpa_t paddr; int dirty = *gpte & PT_DIRTY_MASK; + int was_rmapped = is_rmap_pte(*shadow_pte); + + pgprintk("%s: spte %llx gpte %llx access %llx write_fault %d" + " user_fault %d gfn %lx\n", + __FUNCTION__, *shadow_pte, (u64)*gpte, access_bits, + write_fault, user_fault, gfn); + + if (write_fault && !dirty) { + *gpte |= PT_DIRTY_MASK; + dirty = 1; + FNAME(mark_pagetable_dirty)(vcpu->kvm, walker); + } *shadow_pte |= access_bits << PT_SHADOW_BITS_OFFSET; if (!dirty) @@ -209,7 +224,9 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, paddr = gpa_to_hpa(vcpu, gaddr & PT64_BASE_ADDR_MASK); - *shadow_pte |= access_bits; + *shadow_pte |= PT_PRESENT_MASK; + if (access_bits & PT_USER_MASK) + *shadow_pte |= PT_USER_MASK; if (is_error_hpa(paddr)) { *shadow_pte |= gaddr; @@ -231,37 +248,50 @@ static void FNAME(set_pte_common)(struct kvm_vcpu *vcpu, access_bits &= ~PT_WRITABLE_MASK; } - if (access_bits & PT_WRITABLE_MASK) { + if ((access_bits & PT_WRITABLE_MASK) + || (write_fault && !is_write_protection(vcpu) && !user_fault)) { struct kvm_mmu_page *shadow; + *shadow_pte |= PT_WRITABLE_MASK; + if (user_fault) { + mmu_unshadow(vcpu, gfn); + goto unshadowed; + } + shadow = kvm_mmu_lookup_page(vcpu, gfn); if (shadow) { pgprintk("%s: found shadow page for %lx, marking ro\n", __FUNCTION__, gfn); access_bits &= ~PT_WRITABLE_MASK; if (is_writeble_pte(*shadow_pte)) { - *shadow_pte &= ~PT_WRITABLE_MASK; - kvm_arch_ops->tlb_flush(vcpu); + *shadow_pte &= ~PT_WRITABLE_MASK; + kvm_arch_ops->tlb_flush(vcpu); } + if (write_fault) + *ptwrite = 1; } } +unshadowed: + if (access_bits & PT_WRITABLE_MASK) mark_page_dirty(vcpu->kvm, gaddr >> PAGE_SHIFT); page_header_update_slot(vcpu->kvm, shadow_pte, gaddr); - rmap_add(vcpu, shadow_pte); + if (!was_rmapped) + rmap_add(vcpu, shadow_pte); } static void FNAME(set_pte)(struct kvm_vcpu *vcpu, pt_element_t *gpte, u64 *shadow_pte, u64 access_bits, - int write_fault, gfn_t gfn) + int user_fault, int write_fault, int *ptwrite, + struct guest_walker *walker, gfn_t gfn) { - ASSERT(*shadow_pte == 0); access_bits &= *gpte; - *shadow_pte = (*gpte & PT_PTE_COPY_MASK); + *shadow_pte |= (*gpte & PT_PTE_COPY_MASK); FNAME(set_pte_common)(vcpu, shadow_pte, *gpte & PT_BASE_ADDR_MASK, - gpte, access_bits, write_fault, gfn); + gpte, access_bits, user_fault, write_fault, + ptwrite, walker, gfn); } static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page, @@ -276,31 +306,34 @@ static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *page, return; pgprintk("%s: gpte %llx spte %p\n", __FUNCTION__, (u64)gpte, spte); FNAME(set_pte)(vcpu, &gpte, spte, PT_USER_MASK | PT_WRITABLE_MASK, 0, + 0, NULL, NULL, (gpte & PT_BASE_ADDR_MASK) >> PAGE_SHIFT); } static void FNAME(set_pde)(struct kvm_vcpu *vcpu, pt_element_t *gpde, - u64 *shadow_pte, u64 access_bits, int write_fault, - gfn_t gfn) + u64 *shadow_pte, u64 access_bits, + int user_fault, int write_fault, int *ptwrite, + struct guest_walker *walker, gfn_t gfn) { gpa_t gaddr; - ASSERT(*shadow_pte == 0); access_bits &= *gpde; gaddr = (gpa_t)gfn << PAGE_SHIFT; if (PTTYPE == 32 && is_cpuid_PSE36()) gaddr |= (*gpde & PT32_DIR_PSE36_MASK) << (32 - PT32_DIR_PSE36_SHIFT); - *shadow_pte = *gpde & PT_PTE_COPY_MASK; + *shadow_pte |= *gpde & PT_PTE_COPY_MASK; FNAME(set_pte_common)(vcpu, shadow_pte, gaddr, - gpde, access_bits, write_fault, gfn); + gpde, access_bits, user_fault, write_fault, + ptwrite, walker, gfn); } /* * Fetch a shadow pte for a specific level in the paging hierarchy. */ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, - struct guest_walker *walker, int write_fault) + struct guest_walker *walker, + int user_fault, int write_fault, int *ptwrite) { hpa_t shadow_addr; int level; @@ -330,7 +363,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, shadow_ent = ((u64 *)__va(shadow_addr)) + index; if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) { if (level == PT_PAGE_TABLE_LEVEL) - return shadow_ent; + break; shadow_addr = *shadow_ent & PT64_BASE_ADDR_MASK; prev_shadow_ent = shadow_ent; continue; @@ -365,94 +398,17 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, if (prev_shadow_ent) *prev_shadow_ent |= PT_SHADOW_PS_MARK; FNAME(set_pde)(vcpu, guest_ent, shadow_ent, - walker->inherited_ar, write_fault, walker->gfn); + walker->inherited_ar, user_fault, write_fault, + ptwrite, walker, walker->gfn); } else { ASSERT(walker->level == PT_PAGE_TABLE_LEVEL); FNAME(set_pte)(vcpu, guest_ent, shadow_ent, - walker->inherited_ar, - write_fault, walker->gfn); + walker->inherited_ar, user_fault, write_fault, + ptwrite, walker, walker->gfn); } return shadow_ent; } -/* - * The guest faulted for write. We need to - * - * - check write permissions - * - update the guest pte dirty bit - * - update our own dirty page tracking structures - */ -static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu, - u64 *shadow_ent, - struct guest_walker *walker, - gva_t addr, - int user, - int *write_pt) -{ - pt_element_t *guest_ent; - int writable_shadow; - gfn_t gfn; - struct kvm_mmu_page *page; - - if (is_writeble_pte(*shadow_ent)) - return !user || (*shadow_ent & PT_USER_MASK); - - writable_shadow = *shadow_ent & PT_SHADOW_WRITABLE_MASK; - if (user) { - /* - * User mode access. Fail if it's a kernel page or a read-only - * page. - */ - if (!(*shadow_ent & PT_SHADOW_USER_MASK) || !writable_shadow) - return 0; - ASSERT(*shadow_ent & PT_USER_MASK); - } else - /* - * Kernel mode access. Fail if it's a read-only page and - * supervisor write protection is enabled. - */ - if (!writable_shadow) { - if (is_write_protection(vcpu)) - return 0; - *shadow_ent &= ~PT_USER_MASK; - } - - guest_ent = walker->ptep; - - if (!is_present_pte(*guest_ent)) { - *shadow_ent = 0; - return 0; - } - - gfn = walker->gfn; - - if (user) { - /* - * Usermode page faults won't be for page table updates. - */ - while ((page = kvm_mmu_lookup_page(vcpu, gfn)) != NULL) { - pgprintk("%s: zap %lx %x\n", - __FUNCTION__, gfn, page->role.word); - kvm_mmu_zap_page(vcpu, page); - } - } else if (kvm_mmu_lookup_page(vcpu, gfn)) { - pgprintk("%s: found shadow page for %lx, marking ro\n", - __FUNCTION__, gfn); - mark_page_dirty(vcpu->kvm, gfn); - FNAME(mark_pagetable_dirty)(vcpu->kvm, walker); - *guest_ent |= PT_DIRTY_MASK; - *write_pt = 1; - return 0; - } - mark_page_dirty(vcpu->kvm, gfn); - *shadow_ent |= PT_WRITABLE_MASK; - FNAME(mark_pagetable_dirty)(vcpu->kvm, walker); - *guest_ent |= PT_DIRTY_MASK; - rmap_add(vcpu, shadow_ent); - - return 1; -} - /* * Page fault handler. There are several causes for a page fault: * - there is no shadow pte for the guest pte @@ -475,7 +431,6 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, int fetch_fault = error_code & PFERR_FETCH_MASK; struct guest_walker walker; u64 *shadow_pte; - int fixed; int write_pt = 0; int r; @@ -503,19 +458,10 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, return 0; } - shadow_pte = FNAME(fetch)(vcpu, addr, &walker, write_fault); - pgprintk("%s: shadow pte %p %llx\n", __FUNCTION__, - shadow_pte, *shadow_pte); - - /* - * Update the shadow pte. - */ - if (write_fault) - fixed = FNAME(fix_write_pf)(vcpu, shadow_pte, &walker, addr, - user_fault, &write_pt); - - pgprintk("%s: updated shadow pte %p %llx\n", __FUNCTION__, - shadow_pte, *shadow_pte); + shadow_pte = FNAME(fetch)(vcpu, addr, &walker, user_fault, write_fault, + &write_pt); + pgprintk("%s: shadow pte %p %llx ptwrite %d\n", __FUNCTION__, + shadow_pte, *shadow_pte, write_pt); FNAME(release_walker)(&walker); -- 2.20.1