The page table walk is coded as an infinite loop, with a special
case on the last pte.
Code it as an ordinary loop with a termination condition on the last
pte (large page or walk length exhausted), and put the last pte handling
code after the loop where it belongs.
Signed-off-by: Avi Kivity <a...@redhat.com>
---
arch/x86/kvm/paging_tmpl.h | 58 +++++++++++++++++++---------------------------
1 file changed, 24 insertions(+), 34 deletions(-)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 59c4319..eb4a668 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -131,12 +131,15 @@ static int FNAME(walk_addr_generic)(struct guest_walker
*walker,
gfn_t table_gfn;
unsigned index, pt_access, pte_access;
gpa_t pte_gpa;
- bool eperm, last_gpte;
+ bool eperm;
int offset;
const int write_fault = access & PFERR_WRITE_MASK;
const int user_fault = access & PFERR_USER_MASK;
const int fetch_fault = access & PFERR_FETCH_MASK;
u16 errcode = 0;
+ gpa_t real_gpa;
+ gfn_t gfn;
+ u32 ac;
trace_kvm_mmu_pagetable_walk(addr, access);
retry_walk:
@@ -156,12 +159,16 @@ retry_walk:
ASSERT((!is_long_mode(vcpu) && is_pae(vcpu)) ||
(mmu->get_cr3(vcpu) & CR3_NONPAE_RESERVED_BITS) == 0);
- pt_access = ACC_ALL;
+ pt_access = pte_access = ACC_ALL;
+ ++walker->level;
- for (;;) {
+ do {
gfn_t real_gfn;
unsigned long host_addr;
+ pt_access &= pte_access;
+ --walker->level;
+
index = PT_INDEX(addr, walker->level);
table_gfn = gpte_to_gfn(pte);
@@ -198,8 +205,6 @@ retry_walk:
pte_access = pt_access & gpte_access(vcpu, pte);
eperm |= (mmu->permissions[access >> 1] >> pte_access) & 1;
- last_gpte = FNAME(is_last_gpte)(walker, vcpu, mmu, pte);
-
if (!eperm && unlikely(!(pte & PT_ACCESSED_MASK))) {
int ret;
trace_kvm_mmu_set_accessed_bit(table_gfn, index,
@@ -216,41 +221,26 @@ retry_walk:
}
walker->ptes[walker->level - 1] = pte;
+ } while (!FNAME(is_last_gpte)(walker, vcpu, mmu, pte));
- if (last_gpte) {
- int lvl = walker->level;
- gpa_t real_gpa;
- gfn_t gfn;
- u32 ac;
-
- gfn = gpte_to_gfn_lvl(pte, lvl);
- gfn += (addr & PT_LVL_OFFSET_MASK(lvl)) >> PAGE_SHIFT;
-
- if (PTTYPE == 32 &&
- walker->level == PT_DIRECTORY_LEVEL &&
- is_cpuid_PSE36())
- gfn += pse36_gfn_delta(pte);
-
- ac = write_fault | fetch_fault | user_fault;
+ if (unlikely(eperm)) {
+ errcode |= PFERR_PRESENT_MASK;
+ goto error;
+ }
- real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(gfn),
- ac);
- if (real_gpa == UNMAPPED_GVA)
- return 0;
+ gfn = gpte_to_gfn_lvl(pte, walker->level);
+ gfn += (addr & PT_LVL_OFFSET_MASK(walker->level)) >> PAGE_SHIFT;
- walker->gfn = real_gpa >> PAGE_SHIFT;
+ if (PTTYPE == 32 && walker->level == PT_DIRECTORY_LEVEL &&
is_cpuid_PSE36())
+ gfn += pse36_gfn_delta(pte);
- break;
- }
+ ac = write_fault | fetch_fault | user_fault;
- pt_access &= pte_access;
- --walker->level;
- }
+ real_gpa = mmu->translate_gpa(vcpu, gfn_to_gpa(gfn), ac);
+ if (real_gpa == UNMAPPED_GVA)
+ return 0;
- if (unlikely(eperm)) {
- errcode |= PFERR_PRESENT_MASK;
- goto error;
- }
+ walker->gfn = real_gpa >> PAGE_SHIFT;
if (!write_fault)
protect_clean_gpte(&pte_access, pte);
--
1.7.11.3
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