From: "Hou Wenlong" <houwenlong.hwl@antgroup.com>
To: kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Lai Jiangshan <laijs@linux.alibaba.com>,
linux-kernel@vger.kernel.org
Subject: [PATCH] KVM: x86/mmu: Don't rebuild page when the page is synced and no tlb flushing is required
Date: Tue, 15 Mar 2022 17:35:13 +0800 [thread overview]
Message-ID: <0dabeeb789f57b0d793f85d073893063e692032d.1647336064.git.houwenlong.hwl@antgroup.com> (raw)
Before Commit c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page()
to return true when remote flush is needed"), the return value
of kvm_sync_page() indicates whether the page is synced, and
kvm_mmu_get_page() would rebuild page when the sync fails.
But now, kvm_sync_page() returns false when the page is
synced and no tlb flushing is required, which leads to
rebuild page in kvm_mmu_get_page(). So return the return
value of mmu->sync_page() directly and check it in
kvm_mmu_get_page(). If the sync fails, the page will be
zapped and the invalid_list is not empty, so set flush as
true is accepted in mmu_sync_children().
Fixes: c3e5e415bc1e6 ("KVM: X86: Change kvm_sync_page() to return true when remote flush is needed")
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
---
arch/x86/kvm/mmu/mmu.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 3b8da8b0745e..8efd165ee27c 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1866,17 +1866,14 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
&(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \
if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else
-static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
struct list_head *invalid_list)
{
int ret = vcpu->arch.mmu->sync_page(vcpu, sp);
- if (ret < 0) {
+ if (ret < 0)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
- return false;
- }
-
- return !!ret;
+ return ret;
}
static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm,
@@ -2039,6 +2036,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
struct hlist_head *sp_list;
unsigned quadrant;
struct kvm_mmu_page *sp;
+ int ret;
int collisions = 0;
LIST_HEAD(invalid_list);
@@ -2091,11 +2089,13 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
* If the sync fails, the page is zapped. If so, break
* in order to rebuild it.
*/
- if (!kvm_sync_page(vcpu, sp, &invalid_list))
+ ret = kvm_sync_page(vcpu, sp, &invalid_list);
+ if (ret < 0)
break;
WARN_ON(!list_empty(&invalid_list));
- kvm_flush_remote_tlbs(vcpu->kvm);
+ if (ret > 0)
+ kvm_flush_remote_tlbs(vcpu->kvm);
}
__clear_sp_write_flooding_count(sp);
--
2.31.1
next reply other threads:[~2022-03-15 9:35 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-15 9:35 Hou Wenlong [this message]
2022-03-16 2:19 ` [PATCH] KVM: x86/mmu: Don't rebuild page when the page is synced and no tlb flushing is required Lai Jiangshan
2022-03-24 20:17 ` Sean Christopherson
2022-03-25 11:26 ` Paolo Bonzini
2022-03-25 11:14 ` Paolo Bonzini
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