linux-kernel - [PATCH 5.10 089/120] KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs

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Message-Id: <20210208145821.941981549@linuxfoundation.org>
Date:   Mon,  8 Feb 2021 16:01:16 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Ben Gardon <bgardon@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.10 089/120] KVM: x86/mmu: Fix TDP MMU zap collapsible SPTEs

From: Ben Gardon <bgardon@...gle.com>

commit 87aa9ec939ec7277b730786e19c161c9194cc8ca upstream.

There is a bug in the TDP MMU function to zap SPTEs which could be
replaced with a larger mapping which prevents the function from doing
anything. Fix this by correctly zapping the last level SPTEs.

Cc: stable@...r.kernel.org
Fixes: 14881998566d ("kvm: x86/mmu: Support disabling dirty logging for the tdp MMU")
Signed-off-by: Ben Gardon <bgardon@...gle.com>
Message-Id: <20210202185734.1680553-11-bgardon@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/mmu/tdp_mmu.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1037,8 +1037,8 @@ bool kvm_tdp_mmu_slot_set_dirty(struct k
 }
 
 /*
- * Clear non-leaf entries (and free associated page tables) which could
- * be replaced by large mappings, for GFNs within the slot.
+ * Clear leaf entries which could be replaced by large mappings, for
+ * GFNs within the slot.
  */
 static void zap_collapsible_spte_range(struct kvm *kvm,
 				       struct kvm_mmu_page *root,
@@ -1050,7 +1050,7 @@ static void zap_collapsible_spte_range(s
 
 	tdp_root_for_each_pte(iter, root, start, end) {
 		if (!is_shadow_present_pte(iter.old_spte) ||
-		    is_last_spte(iter.old_spte, iter.level))
+		    !is_last_spte(iter.old_spte, iter.level))
 			continue;
 
 		pfn = spte_to_pfn(iter.old_spte);