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From: Yanan Wang <wangyanan55@huawei.com>
To: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
	"Julien Thierry" <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Gavin Shan <gshan@redhat.com>,
	Quentin Perret <qperret@google.com>
Cc: yuzenghui@huawei.com, wanghaibin.wang@huawei.com,
	Yanan Wang <wangyanan55@huawei.com>,
	zhukeqian1@huawei.com, yezengruan@huawei.com
Subject: [PATCH v2 3/3] KVM: arm64: Mark the page dirty only if the fault is handled successfully
Date: Wed, 16 Dec 2020 20:28:44 +0800	[thread overview]
Message-ID: <20201216122844.25092-4-wangyanan55@huawei.com> (raw)
In-Reply-To: <20201216122844.25092-1-wangyanan55@huawei.com>

We now mark the page dirty and set the bitmap before calling fault handlers
in user_mem_abort(), and we might end up having spurious dirty pages if
update of permissions or mapping has failed.
So, mark the page dirty only if the fault is handled successfully.

Let the guest directly enter again but not return to userspace if we were
trying to recreate the same mapping or only change access permissions
with BBM, which is not permitted in the mapping path.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 arch/arm64/kvm/mmu.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 75814a02d189..72e516a10914 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -879,11 +879,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (vma_pagesize == PAGE_SIZE && !force_pte)
 		vma_pagesize = transparent_hugepage_adjust(memslot, hva,
 							   &pfn, &fault_ipa);
-	if (writable) {
+	if (writable)
 		prot |= KVM_PGTABLE_PROT_W;
-		kvm_set_pfn_dirty(pfn);
-		mark_page_dirty(kvm, gfn);
-	}
 
 	if (fault_status != FSC_PERM && !device)
 		clean_dcache_guest_page(pfn, vma_pagesize);
@@ -911,6 +908,19 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 					     memcache);
 	}
 
+	/* Mark the page dirty only if the fault is handled successfully */
+	if (writable && !ret) {
+		kvm_set_pfn_dirty(pfn);
+		mark_page_dirty(kvm, gfn);
+	}
+
+	/* Let the guest directly enter again if we were trying to recreate the
+	 * same mapping or only change access permissions with BBM, which is not
+	 * permitted in the mapping path.
+	 */
+	if (ret == -EAGAIN)
+		ret = 0;
+
 out_unlock:
 	spin_unlock(&kvm->mmu_lock);
 	kvm_set_pfn_accessed(pfn);
-- 
2.19.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

WARNING: multiple messages have this Message-ID (diff)
From: Yanan Wang <wangyanan55@huawei.com>
To: <linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	Marc Zyngier <maz@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
	"Julien Thierry" <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Gavin Shan <gshan@redhat.com>,
	Quentin Perret <qperret@google.com>
Cc: <wanghaibin.wang@huawei.com>, <yezengruan@huawei.com>,
	<zhukeqian1@huawei.com>, <yuzenghui@huawei.com>,
	Yanan Wang <wangyanan55@huawei.com>
Subject: [PATCH v2 3/3] KVM: arm64: Mark the page dirty only if the fault is handled successfully
Date: Wed, 16 Dec 2020 20:28:44 +0800	[thread overview]
Message-ID: <20201216122844.25092-4-wangyanan55@huawei.com> (raw)
In-Reply-To: <20201216122844.25092-1-wangyanan55@huawei.com>

We now mark the page dirty and set the bitmap before calling fault handlers
in user_mem_abort(), and we might end up having spurious dirty pages if
update of permissions or mapping has failed.
So, mark the page dirty only if the fault is handled successfully.

Let the guest directly enter again but not return to userspace if we were
trying to recreate the same mapping or only change access permissions
with BBM, which is not permitted in the mapping path.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 arch/arm64/kvm/mmu.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 75814a02d189..72e516a10914 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -879,11 +879,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 	if (vma_pagesize == PAGE_SIZE && !force_pte)
 		vma_pagesize = transparent_hugepage_adjust(memslot, hva,
 							   &pfn, &fault_ipa);
-	if (writable) {
+	if (writable)
 		prot |= KVM_PGTABLE_PROT_W;
-		kvm_set_pfn_dirty(pfn);
-		mark_page_dirty(kvm, gfn);
-	}
 
 	if (fault_status != FSC_PERM && !device)
 		clean_dcache_guest_page(pfn, vma_pagesize);
@@ -911,6 +908,19 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
 					     memcache);
 	}
 
+	/* Mark the page dirty only if the fault is handled successfully */
+	if (writable && !ret) {
+		kvm_set_pfn_dirty(pfn);
+		mark_page_dirty(kvm, gfn);
+	}
+
+	/* Let the guest directly enter again if we were trying to recreate the
+	 * same mapping or only change access permissions with BBM, which is not
+	 * permitted in the mapping path.
+	 */
+	if (ret == -EAGAIN)
+		ret = 0;
+
 out_unlock:
 	spin_unlock(&kvm->mmu_lock);
 	kvm_set_pfn_accessed(pfn);
-- 
2.19.1


  parent reply	other threads:[~2020-12-16 12:31 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-16 12:28 [PATCH v2 0/3] RFC: Solve several problems in stage 2 translation Yanan Wang
2020-12-16 12:28 ` Yanan Wang
2020-12-16 12:28 ` [PATCH v2 1/3] KVM: arm64: Decouple partial code of hyp stage 1 mapping and guest stage 2 mapping Yanan Wang
2020-12-16 12:28   ` Yanan Wang
2020-12-16 12:28 ` [PATCH v2 2/3] KVM: arm64: Add prejudgement for relaxing permissions only case in stage2 translation fault handler Yanan Wang
2020-12-16 12:28   ` Yanan Wang
2021-01-13 15:44   ` Will Deacon
2021-01-13 15:44     ` Will Deacon
2021-01-14  9:28     ` wangyanan (Y)
2021-01-14  9:28       ` wangyanan (Y)
2020-12-16 12:28 ` Yanan Wang [this message]
2020-12-16 12:28   ` [PATCH v2 3/3] KVM: arm64: Mark the page dirty only if the fault is handled successfully Yanan Wang
2021-01-13 15:51   ` Will Deacon
2021-01-13 15:51     ` Will Deacon
2021-01-14  9:28     ` wangyanan (Y)
2021-01-14  9:28       ` wangyanan (Y)
2020-12-28  2:46 ` [PATCH v2 0/3] RFC: Solve several problems in stage 2 translation wangyanan (Y)
2020-12-28  2:46   ` wangyanan (Y)

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