From: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
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@xxxxxxxxxxxxx>
---
arch/x86/kvm/paging_tmpl.h | 26 ++++++++++++--------------
1 files changed, 12 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 52450a6..f9d9af1 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -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);
@@ -234,9 +232,9 @@ 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)
@@ -293,9 +291,9 @@ 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)
--
1.7.1
--
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