linux-kernel - [PATCH] kvm: don't lose the higher 32 bits of tlbs

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Date:   Sun, 13 Dec 2020 12:49:13 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Lai Jiangshan <laijs@...ux.alibaba.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH] kvm: don't lose the higher 32 bits of tlbs_dirty

From: Lai Jiangshan <laijs@...ux.alibaba.com>

In kvm_mmu_notifier_invalidate_range_start(), tlbs_dirty is used as:
	need_tlb_flush |= kvm->tlbs_dirty;
with need_tlb_flush's type being int and tlbs_dirty's type being long.

It means that tlbs_dirty is always used as int and the higher 32 bits
is useless. We can just change need_tlb_flush's type to long to
make full use of tlbs_dirty.

Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 virt/kvm/kvm_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2541a17ff1c4..4e519a517e9f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -470,7 +470,8 @@ static int kvm_mmu_notifier_invalidate_range_start(struct mmu_notifier *mn,
 					const struct mmu_notifier_range *range)
 {
 	struct kvm *kvm = mmu_notifier_to_kvm(mn);
-	int need_tlb_flush = 0, idx;
+	long need_tlb_flush = 0;
+	int idx;
 
 	idx = srcu_read_lock(&kvm->srcu);
 	spin_lock(&kvm->mmu_lock);
-- 
2.19.1.6.gb485710b