From c6c4f961cb879aed67b1343bdef2087c899fdaa9 Mon Sep 17 00:00:00 2001
From: Li RongQing <lirongqing@baidu.com>
Date: Sun, 27 Sep 2020 16:44:57 +0800
Subject: [PATCH] KVM: x86/mmu: fix counting of rmap entries in pte_list_add
Fix an off-by-one style bug in pte_list_add() where it failed to
account the last full set of SPTEs, i.e. when desc->sptes is full
and desc->more is NULL.
Merge the two "PTE_LIST_EXT-1" checks as part of the fix to avoid
an extra comparison.
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <1601196297-24104-1-git-send-email-lirongqing@baidu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
arch/x86/kvm/mmu/mmu.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 1f96adff8dc4fa..5bb1939b65d8d9 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -856,12 +856,14 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
} else {
rmap_printk("pte_list_add: %p %llx many->many\n", spte, *spte);
desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
- while (desc->sptes[PTE_LIST_EXT-1] && desc->more) {
- desc = desc->more;
+ while (desc->sptes[PTE_LIST_EXT-1]) {
count += PTE_LIST_EXT;
- }
- if (desc->sptes[PTE_LIST_EXT-1]) {
- desc->more = mmu_alloc_pte_list_desc(vcpu);
+
+ if (!desc->more) {
+ desc->more = mmu_alloc_pte_list_desc(vcpu);
+ desc = desc->more;
+ break;
+ }
desc = desc->more;
}
for (i = 0; desc->sptes[i]; ++i)
--
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