From: Vipin Sharma <vipinsh@google.com>
To: maz@kernel.org, oliver.upton@linux.dev, james.morse@arm.com,
suzuki.poulose@arm.com, yuzenghui@huawei.com,
catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org,
aleksandar.qemu.devel@gmail.com, tsbogend@alpha.franken.de,
anup@brainfault.org, atishp@atishpatra.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, seanjc@google.com, pbonzini@redhat.com,
dmatlack@google.com, ricarkol@google.com
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org,
linux-riscv@lists.infradead.org,
linux-kselftest@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, Vipin Sharma <vipinsh@google.com>
Subject: [PATCH v2 13/16] KVM: arm64: Run clear-dirty-log under MMU read lock
Date: Fri, 2 Jun 2023 09:09:11 -0700 [thread overview]
Message-ID: <20230602160914.4011728-14-vipinsh@google.com> (raw)
In-Reply-To: <20230602160914.4011728-1-vipinsh@google.com>
Take MMU read lock for clearing dirty logs and use shared page table
walker.
Dirty logs are currently cleared using MMU write locks. This
means vCPUs page faults, which takes MMU read lock, will
be blocked while dirty logs are being cleared. This causes guest
degradation and especially noticeable on VMs with lot of vCPUs.
Taking MMU read lock will allow vCPUs to execute parallelly and reduces
the impact on vCPUs performance.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/arm64/kvm/mmu.c | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 356dc4131023..7c966f6f1a41 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -74,8 +74,12 @@ static int stage2_apply_range(struct kvm_s2_mmu *mmu, phys_addr_t addr,
if (ret)
break;
- if (resched && next != end)
- cond_resched_rwlock_write(&kvm->mmu_lock);
+ if (resched && next != end) {
+ if (flags & KVM_PGTABLE_WALK_SHARED)
+ cond_resched_rwlock_read(&kvm->mmu_lock);
+ else
+ cond_resched_rwlock_write(&kvm->mmu_lock);
+ }
} while (addr = next, addr != end);
return ret;
@@ -1131,11 +1135,11 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
phys_addr_t start = (base_gfn + __ffs(mask)) << PAGE_SHIFT;
phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
- write_lock(&kvm->mmu_lock);
- lockdep_assert_held_write(&kvm->mmu_lock);
-
- stage2_wp_range(&kvm->arch.mmu, start, end, 0);
+ read_lock(&kvm->mmu_lock);
+ stage2_wp_range(&kvm->arch.mmu, start, end, KVM_PGTABLE_WALK_SHARED);
+ read_unlock(&kvm->mmu_lock);
+ write_lock(&kvm->mmu_lock);
/*
* Eager-splitting is done when manual-protect is set. We
* also check for initially-all-set because we can avoid
--
2.41.0.rc0.172.g3f132b7071-goog
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2023-06-02 16:35 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-02 16:08 [PATCH v2 00/16] Use MMU read lock for clear-dirty-log Vipin Sharma
2023-06-02 16:08 ` [PATCH v2 01/16] KVM: selftests: Clear dirty logs in user defined chunks sizes in dirty_log_perf_test Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 02/16] KVM: selftests: Add optional delay between consecutive clear-dirty-log calls Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 03/16] KVM: selftests: Pass the count of read and write accesses from guest to host Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 04/16] KVM: selftests: Print read-write progress by vCPUs in dirty_log_perf_test Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 05/16] KVM: selftests: Allow independent execution of " Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 06/16] KVM: arm64: Correct the kvm_pgtable_stage2_flush() documentation Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 07/16] KVM: mmu: Move mmu lock/unlock to arch code for clear dirty log Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 08/16] KMV: arm64: Pass page table walker flags to stage2_apply_range_*() Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 09/16] KVM: arm64: Document the page table walker actions based on the callback's return value Vipin Sharma
2023-06-05 14:35 ` Zhi Wang
2023-06-06 17:30 ` Vipin Sharma
2023-06-07 12:37 ` Zhi Wang
2023-06-08 20:17 ` Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 10/16] KVM: arm64: Return -ENOENT if PTE is not valid in stage2_attr_walker Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 11/16] KVM: arm64: Use KVM_PGTABLE_WALK_SHARED flag instead of KVM_PGTABLE_WALK_HANDLE_FAULT Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 12/16] KVM: arm64: Retry shared page table walks outside of fault handler Vipin Sharma
2023-06-02 16:09 ` Vipin Sharma [this message]
2023-06-02 16:09 ` [PATCH v2 14/16] KVM: arm64: Pass page walker flags from callers of stage 2 split walker Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 15/16] KVM: arm64: Provide option to pass page walker flag for huge page splits Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 16/16] KVM: arm64: Split huge pages during clear-dirty-log under MMU read lock Vipin Sharma
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230602160914.4011728-14-vipinsh@google.com \
--to=vipinsh@google.com \
--cc=aleksandar.qemu.devel@gmail.com \
--cc=anup@brainfault.org \
--cc=aou@eecs.berkeley.edu \
--cc=atishp@atishpatra.org \
--cc=catalin.marinas@arm.com \
--cc=chenhuacai@kernel.org \
--cc=dmatlack@google.com \
--cc=james.morse@arm.com \
--cc=kvm-riscv@lists.infradead.org \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.linux.dev \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=linux-mips@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=maz@kernel.org \
--cc=oliver.upton@linux.dev \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=pbonzini@redhat.com \
--cc=ricarkol@google.com \
--cc=seanjc@google.com \
--cc=suzuki.poulose@arm.com \
--cc=tsbogend@alpha.franken.de \
--cc=will@kernel.org \
--cc=yuzenghui@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).