[PATCH 7/7] KVM: X86: Also prefetch the last range in __direct_pte_prefetch().

[Lai Jiangshan]

From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>

__direct_pte_prefetch() skips prefetching the last range.

The last range are often the whole range after the faulted spte when
guest is touching huge-page-mapped(in guest view) memory forwardly
which means prefetching them can reduce pagefault.

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
---
 arch/x86/kvm/mmu/mmu.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e5932af6f11c..ac260e01e9d8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2847,8 +2847,9 @@ static void __direct_pte_prefetch(struct kvm_vcpu *vcpu,
 	i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1);
 	spte = sp->spt + i;
 
-	for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
-		if (is_shadow_present_pte(*spte) || spte == sptep) {
+	for (i = 0; i <= PTE_PREFETCH_NUM; i++, spte++) {
+		if (i == PTE_PREFETCH_NUM ||
+		    is_shadow_present_pte(*spte) || spte == sptep) {
 			if (!start)
 				continue;
 			if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0)
-- 
2.19.1.6.gb485710b