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[PATCH] KVM: MMU: Fold fetch_guest() into init_walker()

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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 <avi@qumranet.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Avi Kivity 2007-01-05 16:36:40 -08:00 committed by Linus Torvalds
parent 1342d3536d
commit ac79c978f1
1 changed files with 47 additions and 58 deletions
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105
drivers/kvm/paging_tmpl.h
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@ -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))