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KVM: MMU: Use ptep_user for cmpxchg_gpte()

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The address of the gpte was already calculated and stored in ptep_user
before entering cmpxchg_gpte().

This patch makes cmpxchg_gpte() to use that to make it clear that we
are using the same address during walk_addr_generic().

Note that the unlikely annotations are used to show that the conditions
are something unusual rather than for performance.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2011-05-01 14:33:07 +09:00 committed by Avi Kivity
parent 85722cda30
commit c8cfbb555e
1 changed files with 12 additions and 14 deletions
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26
arch/x86/kvm/paging_tmpl.h
View File

@ -79,21 +79,19 @@ static gfn_t gpte_to_gfn_lvl(pt_element_t gpte, int lvl)
}
static int FNAME(cmpxchg_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
gfn_t table_gfn, unsigned index,
pt_element_t orig_pte, pt_element_t new_pte)
pt_element_t __user *ptep_user, unsigned index,
pt_element_t orig_pte, pt_element_t new_pte)
{
int npages;
pt_element_t ret;
pt_element_t *table;
struct page *page;
gpa_t gpa;
gpa = mmu->translate_gpa(vcpu, table_gfn << PAGE_SHIFT,
PFERR_USER_MASK|PFERR_WRITE_MASK);
if (gpa == UNMAPPED_GVA)
npages = get_user_pages_fast((unsigned long)ptep_user, 1, 1, &page);
/* Check if the user is doing something meaningless. */
if (unlikely(npages != 1))
return -EFAULT;
page = gfn_to_page(vcpu->kvm, gpa_to_gfn(gpa));
table = kmap_atomic(page, KM_USER0);
ret = CMPXCHG(&table[index], orig_pte, new_pte);
kunmap_atomic(table, KM_USER0);
@ -220,9 +218,9 @@ walk:
int ret;
trace_kvm_mmu_set_accessed_bit(table_gfn, index,
sizeof(pte));
ret = FNAME(cmpxchg_gpte)(vcpu, mmu, table_gfn,
index, pte, pte|PT_ACCESSED_MASK);
if (ret < 0) {
ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index,
pte, pte|PT_ACCESSED_MASK);
if (unlikely(ret < 0)) {
present = false;
break;
} else if (ret)
@ -279,9 +277,9 @@ walk:
int ret;
trace_kvm_mmu_set_dirty_bit(table_gfn, index, sizeof(pte));
ret = FNAME(cmpxchg_gpte)(vcpu, mmu, table_gfn, index, pte,
pte|PT_DIRTY_MASK);
if (ret < 0) {
ret = FNAME(cmpxchg_gpte)(vcpu, mmu, ptep_user, index,
pte, pte|PT_DIRTY_MASK);
if (unlikely(ret < 0)) {
present = false;
goto error;
} else if (ret)