kvm_mmu_pte_write() reads guest ptes in two different occasions, both to
allow a 32-bit pae guest to update a pte with 4-byte writes. Consolidate
these into a single read, which also allows us to consolidate another read
from an invlpg speculating a gpte into the shadow page table.
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
arch/x86/kvm/mmu.c | 69 +++++++++++++++++++++++----------------------------
1 files changed, 31 insertions(+), 38 deletions(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b137515..f63c9ad 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2556,36 +2556,11 @@ static bool last_updated_pte_accessed(struct kvm_vcpu *vcpu)
}
static void mmu_guess_page_from_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
- const u8 *new, int bytes)
+ u64 gpte)
{
gfn_t gfn;
- int r;
- u64 gpte = 0;
pfn_t pfn;
- if (bytes != 4 && bytes != 8)
- return;
-
- /*
- * Assume that the pte write on a page table of the same type
- * as the current vcpu paging mode. This is nearly always true
- * (might be false while changing modes). Note it is verified later
- * by update_pte().
- */
- if (is_pae(vcpu)) {
- /* Handle a 32-bit guest writing two halves of a 64-bit gpte */
- if ((bytes == 4) && (gpa % 4 == 0)) {
- r = kvm_read_guest(vcpu->kvm, gpa & ~(u64)7, &gpte, 8);
- if (r)
- return;
- memcpy((void *)&gpte + (gpa % 8), new, 4);
- } else if ((bytes == 8) && (gpa % 8 == 0)) {
- memcpy((void *)&gpte, new, 8);
- }
- } else {
- if ((bytes == 4) && (gpa % 4 == 0))
- memcpy((void *)&gpte, new, 4);
- }
if (!is_present_gpte(gpte))
return;
gfn = (gpte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT;
@@ -2636,7 +2611,34 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
int r;
pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes);
- mmu_guess_page_from_pte_write(vcpu, gpa, new, bytes);
+
+ switch (bytes) {
+ case 4:
+ gentry = *(const u32 *)new;
+ break;
+ case 8:
+ gentry = *(const u64 *)new;
+ break;
+ default:
+ gentry = 0;
+ break;
+ }
+
+ /*
+ * Assume that the pte write on a page table of the same type
+ * as the current vcpu paging mode. This is nearly always true
+ * (might be false while changing modes). Note it is verified later
+ * by update_pte().
+ */
+ if (is_pae(vcpu) && bytes == 4) {
+ /* Handle a 32-bit guest writing two halves of a 64-bit gpte */
+ gpa &= ~(gpa_t)7;
+ r = kvm_read_guest(vcpu->kvm, gpa, &gentry, 8);
+ if (r)
+ gentry = 0;
+ }
+
+ mmu_guess_page_from_pte_write(vcpu, gpa, gentry);
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_access_page(vcpu, gfn);
kvm_mmu_free_some_pages(vcpu);
@@ -2701,20 +2703,11 @@ void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa,
continue;
}
spte = &sp->spt[page_offset / sizeof(*spte)];
- if ((gpa & (pte_size - 1)) || (bytes < pte_size)) {
- gentry = 0;
- r = kvm_read_guest_atomic(vcpu->kvm,
- gpa & ~(u64)(pte_size - 1),
- &gentry, pte_size);
- new = (const void *)&gentry;
- if (r < 0)
- new = NULL;
- }
while (npte--) {
entry = *spte;
mmu_pte_write_zap_pte(vcpu, sp, spte);
- if (new)
- mmu_pte_write_new_pte(vcpu, sp, spte, new);
+ if (gentry)
+ mmu_pte_write_new_pte(vcpu, sp, spte, &gentry);
mmu_pte_write_flush_tlb(vcpu, entry, *spte);
++spte;
}
--
1.7.0.2
--
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