From: Yanan Wang <wangyanan55@huawei.com>
To: Marc Zyngier <maz@kernel.org>, Will Deacon <will@kernel.org>,
"Quentin Perret" <qperret@google.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
<kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>, <kvm@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
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>, <wanghaibin.wang@huawei.com>,
<zhukeqian1@huawei.com>, <yuzenghui@huawei.com>,
Yanan Wang <wangyanan55@huawei.com>
Subject: [PATCH v5 6/6] KVM: arm64: Distinguish cases of memcache allocations completely
Date: Thu, 15 Apr 2021 19:50:32 +0800 [thread overview]
Message-ID: <20210415115032.35760-7-wangyanan55@huawei.com> (raw)
In-Reply-To: <20210415115032.35760-1-wangyanan55@huawei.com>
With a guest translation fault, the memcache pages are not needed if KVM
is only about to install a new leaf entry into the existing page table.
And with a guest permission fault, the memcache pages are also not needed
for a write_fault in dirty-logging time if KVM is only about to update
the existing leaf entry instead of collapsing a block entry into a table.
By comparing fault_granule and vma_pagesize, cases that require allocations
from memcache and cases that don't can be distinguished completely.
Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
arch/arm64/kvm/mmu.c | 25 ++++++++++++-------------
1 file changed, 12 insertions(+), 13 deletions(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index aa536392b308..9e35aa5d29f2 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -895,19 +895,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
gfn = fault_ipa >> PAGE_SHIFT;
mmap_read_unlock(current->mm);
- /*
- * Permission faults just need to update the existing leaf entry,
- * and so normally don't require allocations from the memcache. The
- * only exception to this is when dirty logging is enabled at runtime
- * and a write fault needs to collapse a block entry into a table.
- */
- if (fault_status != FSC_PERM || (logging_active && write_fault)) {
- ret = kvm_mmu_topup_memory_cache(memcache,
- kvm_mmu_cache_min_pages(kvm));
- if (ret)
- return ret;
- }
-
mmu_seq = vcpu->kvm->mmu_notifier_seq;
/*
* Ensure the read of mmu_notifier_seq happens before we call
@@ -970,6 +957,18 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
else if (cpus_have_const_cap(ARM64_HAS_CACHE_DIC))
prot |= KVM_PGTABLE_PROT_X;
+ /*
+ * Allocations from the memcache are required only when granule of the
+ * lookup level where the guest fault happened exceeds vma_pagesize,
+ * which means new page tables will be created in the fault handlers.
+ */
+ if (fault_granule > vma_pagesize) {
+ ret = kvm_mmu_topup_memory_cache(memcache,
+ kvm_mmu_cache_min_pages(kvm));
+ if (ret)
+ return ret;
+ }
+
/*
* Under the premise of getting a FSC_PERM fault, we just need to relax
* permissions only if vma_pagesize equals fault_granule. Otherwise,
--
2.23.0
next prev parent reply other threads:[~2021-04-15 11:51 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 11:50 [PATCH v5 0/6] KVM: arm64: Improve efficiency of stage2 page table Yanan Wang
2021-04-15 11:50 ` [PATCH v5 1/6] KVM: arm64: Introduce KVM_PGTABLE_S2_GUEST stage-2 flag Yanan Wang
2021-06-02 10:43 ` Quentin Perret
2021-06-03 12:36 ` wangyanan (Y)
2021-04-15 11:50 ` [PATCH v5 2/6] KVM: arm64: Move D-cache flush to the fault handlers Yanan Wang
[not found] ` <877djc1sca.wl-maz@kernel.org>
2021-06-02 10:49 ` Quentin Perret
2021-06-03 12:33 ` wangyanan (Y)
2021-04-15 11:50 ` [PATCH v5 3/6] KVM: arm64: Add mm_ops member for structure stage2_attr_data Yanan Wang
2021-04-15 11:50 ` [PATCH v5 4/6] KVM: arm64: Provide invalidate_icache_range at non-VHE EL2 Yanan Wang
[not found] ` <875yyw1s73.wl-maz@kernel.org>
2021-06-03 12:34 ` wangyanan (Y)
2021-04-15 11:50 ` [PATCH v5 5/6] KVM: arm64: Move I-cache flush to the fault handlers Yanan Wang
2021-06-02 10:58 ` Quentin Perret
2021-06-03 12:35 ` wangyanan (Y)
2021-04-15 11:50 ` Yanan Wang [this message]
2021-06-02 11:07 ` [PATCH v5 6/6] KVM: arm64: Distinguish cases of memcache allocations completely Quentin Perret
2021-06-03 12:52 ` wangyanan (Y)
2021-05-12 12:54 ` [PATCH v5 0/6] KVM: arm64: Improve efficiency of stage2 page table wangyanan (Y)
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