From 694627e6c4ce3b20ebeda81e87b020ac4820727a Mon Sep 17 00:00:00 2001 From: Keqian Zhu Date: Mon, 13 Apr 2020 20:20:23 +0800 Subject: [PATCH] KVM: arm64: Support enabling dirty log gradually in small chunks mainline inclusion from mainline-v5.10 commit: c862626e19efdc26b26481515470b160e8fe52f3 category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I66COX CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-5.10.y&id=c862626e19efdc26b26481515470b160e8fe52f3 -------------------------------- There is already support of enabling dirty log gradually in small chunks for x86 in commit 3c9bd4006bfc ("KVM: x86: enable dirty log gradually in small chunks"). This adds support for arm64. x86 still writes protect all huge pages when DIRTY_LOG_INITIALLY_ALL_SET is enabled. However, for arm64, both huge pages and normal pages can be write protected gradually by userspace. Under the Huawei Kunpeng 920 2.6GHz platform, I did some tests on 128G Linux VMs with different page size. The memory pressure is 127G in each case. The time taken of memory_global_dirty_log_start in QEMU is listed below: Page Size Before After Optimization 4K 650ms 1.8ms 2M 4ms 1.8ms 1G 2ms 1.8ms Besides the time reduction, the biggest improvement is that we will minimize the performance side effect (because of dissolving huge pages and marking memslots dirty) on guest after enabling dirty log. Signed-off-by: Keqian Zhu Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20200413122023.52583-1-zhukeqian1@huawei.com --- Documentation/virtual/kvm/api.txt | 2 +- arch/arm64/include/asm/kvm_host.h | 3 +++ virt/kvm/arm/mmu.c | 12 ++++++++++-- 3 files changed, 14 insertions(+), 3 deletions(-) diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index c4770f01cea1..f03924c4353a 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -4658,7 +4658,7 @@ will be initialized to 1 when created. This also improves performance because dirty logging can be enabled gradually in small chunks on the first call to KVM_CLEAR_DIRTY_LOG. KVM_DIRTY_LOG_INITIALLY_SET depends on KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE (it is also only available on -x86 for now). +x86 and arm64 for now). KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2 was previously available under the name KVM_CAP_MANUAL_DIRTY_LOG_PROTECT, but the implementation had bugs that make diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index bf03056e3751..6eeaec218d9f 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -53,6 +53,9 @@ #define KVM_REQ_IRQ_PENDING KVM_ARCH_REQ(1) #define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(2) +#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \ + KVM_DIRTY_LOG_INITIALLY_SET) + DECLARE_STATIC_KEY_FALSE(userspace_irqchip_in_use); int __attribute_const__ kvm_target_cpu(void); diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c index aec599488847..2c183030f32e 100644 --- a/virt/kvm/arm/mmu.c +++ b/virt/kvm/arm/mmu.c @@ -2304,8 +2304,16 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, * allocated dirty_bitmap[], dirty pages will be be tracked while the * memory slot is write protected. */ - if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES) - kvm_mmu_wp_memory_region(kvm, mem->slot); + if (change != KVM_MR_DELETE && mem->flags & KVM_MEM_LOG_DIRTY_PAGES) { + /* + * If we're with initial-all-set, we don't need to write + * protect any pages because they're all reported as dirty. + * Huge pages and normal pages will be write protect gradually. + */ + if (!kvm_dirty_log_manual_protect_and_init_set(kvm)) { + kvm_mmu_wp_memory_region(kvm, mem->slot); + } + } } int kvm_arch_prepare_memory_region(struct kvm *kvm, -- GitLab