From: Zenghui Yu <yuzenghui@huawei.com>
To: <christoffer.dall@arm.com>, <marc.zyngier@arm.com>
Cc: <james.morse@arm.com>, <julien.thierry@arm.com>,
<suzuki.poulose@arm.com>, <wanghaibin.wang@huawei.com>,
<kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, Zenghui Yu <yuzenghui@huawei.com>,
Punit Agrawal <punit.agrawal@arm.com>
Subject: [RFC PATCH] KVM: arm64: Force a PTE mapping when logging is enabled
Date: Sat, 2 Mar 2019 03:35:28 +0000 [thread overview]
Message-ID: <1551497728-12576-1-git-send-email-yuzenghui@huawei.com> (raw)
The idea behind this is: we don't want to keep tracking of huge pages when
logging_active is true, which will result in performance degradation. We
still need to set vma_pagesize to PAGE_SIZE, so that we can make use of it
to force a PTE mapping.
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
---
Atfer looking into https://patchwork.codeaurora.org/patch/647985/ , the
"vma_pagesize = PAGE_SIZE" logic was not intended to be deleted. As far
as I can tell, we used to have "hugetlb" to force the PTE mapping, but
we have "vma_pagesize" currently instead. We should set it properly for
performance reasons (e.g, in VM migration). Did I miss something important?
---
virt/kvm/arm/mmu.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 30251e2..7d41b16 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1705,6 +1705,13 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
(vma_pagesize == PUD_SIZE && kvm_stage2_has_pmd(kvm))) &&
!force_pte) {
gfn = (fault_ipa & huge_page_mask(hstate_vma(vma))) >> PAGE_SHIFT;
+ } else {
+ /*
+ * Fallback to PTE if it's not one of the stage2
+ * supported hugepage sizes or the corresponding level
+ * doesn't exist, or logging is enabled.
+ */
+ vma_pagesize = PAGE_SIZE;
}
up_read(¤t->mm->mmap_sem);
--
1.8.3.1
next reply other threads:[~2019-03-02 3:39 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-02 3:35 Zenghui Yu [this message]
2019-03-03 15:14 ` [RFC PATCH] KVM: arm64: Force a PTE mapping when logging is enabled Zenghui Yu
2019-03-04 17:13 ` Suzuki K Poulose
2019-03-04 17:34 ` Marc Zyngier
2019-03-05 11:09 ` Zenghui Yu
2019-03-05 11:13 ` Suzuki K Poulose
2019-03-05 11:32 ` Zenghui Yu
2019-03-05 11:51 ` Marc Zyngier
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