From ac79c978f173586ab3624427c89cd22b393cabd4 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Fri, 5 Jan 2007 16:36:40 -0800 Subject: [PATCH] [PATCH] KVM: MMU: Fold fetch_guest() into init_walker() It is never necessary to fetch a guest entry from an intermediate page table level (except for large pages), so avoid some confusion by always descending into the lowest possible level. Rename init_walker() to walk_addr() as it is no longer restricted to initialization. Signed-off-by: Avi Kivity Acked-by: Ingo Molnar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/kvm/paging_tmpl.h | 105 +++++++++++++++++--------------------- 1 file changed, 47 insertions(+), 58 deletions(-) diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h index 3a35c8067de..963d80e2271 100644 --- a/drivers/kvm/paging_tmpl.h +++ b/drivers/kvm/paging_tmpl.h @@ -54,14 +54,19 @@ struct guest_walker { int level; gfn_t table_gfn; pt_element_t *table; + pt_element_t *ptep; pt_element_t inherited_ar; }; -static void FNAME(init_walker)(struct guest_walker *walker, - struct kvm_vcpu *vcpu) +/* + * Fetch a guest pte for a guest virtual address + */ +static void FNAME(walk_addr)(struct guest_walker *walker, + struct kvm_vcpu *vcpu, gva_t addr) { hpa_t hpa; struct kvm_memory_slot *slot; + pt_element_t *ptep; walker->level = vcpu->mmu.root_level; walker->table_gfn = (vcpu->cr3 & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT; @@ -75,6 +80,38 @@ static void FNAME(init_walker)(struct guest_walker *walker, walker->table = (pt_element_t *)( (unsigned long)walker->table | (unsigned long)(vcpu->cr3 & ~(PAGE_MASK | CR3_FLAGS_MASK)) ); walker->inherited_ar = PT_USER_MASK | PT_WRITABLE_MASK; + + for (;;) { + int index = PT_INDEX(addr, walker->level); + hpa_t paddr; + + ptep = &walker->table[index]; + ASSERT(((unsigned long)walker->table & PAGE_MASK) == + ((unsigned long)ptep & PAGE_MASK)); + + /* Don't set accessed bit on PAE PDPTRs */ + if (vcpu->mmu.root_level != 3 || walker->level != 3) + if ((*ptep & (PT_PRESENT_MASK | PT_ACCESSED_MASK)) + == PT_PRESENT_MASK) + *ptep |= PT_ACCESSED_MASK; + + if (!is_present_pte(*ptep) || + walker->level == PT_PAGE_TABLE_LEVEL || + (walker->level == PT_DIRECTORY_LEVEL && + (*ptep & PT_PAGE_SIZE_MASK) && + (PTTYPE == 64 || is_pse(vcpu)))) + break; + + if (walker->level != 3 || is_long_mode(vcpu)) + walker->inherited_ar &= walker->table[index]; + walker->table_gfn = (*ptep & PT_BASE_ADDR_MASK) >> PAGE_SHIFT; + paddr = safe_gpa_to_hpa(vcpu, *ptep & PT_BASE_ADDR_MASK); + kunmap_atomic(walker->table, KM_USER0); + walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT), + KM_USER0); + --walker->level; + } + walker->ptep = ptep; } static void FNAME(release_walker)(struct guest_walker *walker) @@ -109,41 +146,6 @@ static void FNAME(set_pde)(struct kvm_vcpu *vcpu, u64 guest_pde, guest_pde & PT_DIRTY_MASK, access_bits); } -/* - * Fetch a guest pte from a specific level in the paging hierarchy. - */ -static pt_element_t *FNAME(fetch_guest)(struct kvm_vcpu *vcpu, - struct guest_walker *walker, - int level, - gva_t addr) -{ - - ASSERT(level > 0 && level <= walker->level); - - for (;;) { - int index = PT_INDEX(addr, walker->level); - hpa_t paddr; - - ASSERT(((unsigned long)walker->table & PAGE_MASK) == - ((unsigned long)&walker->table[index] & PAGE_MASK)); - if (level == walker->level || - !is_present_pte(walker->table[index]) || - (walker->level == PT_DIRECTORY_LEVEL && - (walker->table[index] & PT_PAGE_SIZE_MASK) && - (PTTYPE == 64 || is_pse(vcpu)))) - return &walker->table[index]; - if (walker->level != 3 || is_long_mode(vcpu)) - walker->inherited_ar &= walker->table[index]; - walker->table_gfn = (walker->table[index] & PT_BASE_ADDR_MASK) - >> PAGE_SHIFT; - paddr = safe_gpa_to_hpa(vcpu, walker->table[index] & PT_BASE_ADDR_MASK); - kunmap_atomic(walker->table, KM_USER0); - walker->table = kmap_atomic(pfn_to_page(paddr >> PAGE_SHIFT), - KM_USER0); - --walker->level; - } -} - /* * Fetch a shadow pte for a specific level in the paging hierarchy. */ @@ -153,6 +155,10 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, hpa_t shadow_addr; int level; u64 *prev_shadow_ent = NULL; + pt_element_t *guest_ent = walker->ptep; + + if (!is_present_pte(*guest_ent)) + return NULL; shadow_addr = vcpu->mmu.root_hpa; level = vcpu->mmu.shadow_root_level; @@ -160,7 +166,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, for (; ; level--) { u32 index = SHADOW_PT_INDEX(addr, level); u64 *shadow_ent = ((u64 *)__va(shadow_addr)) + index; - pt_element_t *guest_ent; u64 shadow_pte; if (is_present_pte(*shadow_ent) || is_io_pte(*shadow_ent)) { @@ -171,21 +176,6 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr, continue; } - if (PTTYPE == 32 && level > PT32_ROOT_LEVEL) { - ASSERT(level == PT32E_ROOT_LEVEL); - guest_ent = FNAME(fetch_guest)(vcpu, walker, - PT32_ROOT_LEVEL, addr); - } else - guest_ent = FNAME(fetch_guest)(vcpu, walker, - level, addr); - - if (!is_present_pte(*guest_ent)) - return NULL; - - /* Don't set accessed bit on PAE PDPTRs */ - if (vcpu->mmu.root_level != 3 || walker->level != 3) - *guest_ent |= PT_ACCESSED_MASK; - if (level == PT_PAGE_TABLE_LEVEL) { if (walker->level == PT_DIRECTORY_LEVEL) { @@ -253,7 +243,7 @@ static int FNAME(fix_write_pf)(struct kvm_vcpu *vcpu, *shadow_ent &= ~PT_USER_MASK; } - guest_ent = FNAME(fetch_guest)(vcpu, walker, PT_PAGE_TABLE_LEVEL, addr); + guest_ent = walker->ptep; if (!is_present_pte(*guest_ent)) { *shadow_ent = 0; @@ -296,7 +286,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, * Look up the shadow pte for the faulting address. */ for (;;) { - FNAME(init_walker)(&walker, vcpu); + FNAME(walk_addr)(&walker, vcpu, addr); shadow_pte = FNAME(fetch)(vcpu, addr, &walker); if (IS_ERR(shadow_pte)) { /* must be -ENOMEM */ nonpaging_flush(vcpu); @@ -357,9 +347,8 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr) pt_element_t guest_pte; gpa_t gpa; - FNAME(init_walker)(&walker, vcpu); - guest_pte = *FNAME(fetch_guest)(vcpu, &walker, PT_PAGE_TABLE_LEVEL, - vaddr); + FNAME(walk_addr)(&walker, vcpu, vaddr); + guest_pte = *walker.ptep; FNAME(release_walker)(&walker); if (!is_present_pte(guest_pte)) -- 2.41.1