From nobody Mon Feb 9 14:32:42 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C024C7EE2A for ; Fri, 2 Jun 2023 16:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236871AbjFBQLG (ORCPT ); Fri, 2 Jun 2023 12:11:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236698AbjFBQKq (ORCPT ); Fri, 2 Jun 2023 12:10:46 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA400197 for ; Fri, 2 Jun 2023 09:10:04 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bb1e332f648so2298623276.0 for ; Fri, 02 Jun 2023 09:10:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685722186; x=1688314186; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=iiQKR5r12cEmfxEtqKB501qQ7U5/inaqlNqkSHrg1Dk=; b=pa3mVvglr9ldo0oASWJgWygRLd3hw8lG1pjLeB+Qzm3K3zOU5BQU88aja7wxcgPXwA AwayadZx6shxLAXjuJFrDzlMtsvb67kGNUVBIz8jQ9pcx5Jd6BF7pMABQixgPuk47qo/ QPSMIrvsitPTIbIvBs3Unmlez10KGpvyazPz0vuoWxeM0ddu7MUX6bOpsZv5FX/RHsfI ab0UhQ4BKG9ohwFpekgRN7rsQtHAtMFU2PEbvOsbX5+K7m399sRVLlUcmEJAu36XrUm4 MIK72o4Xoc2dnSjS77GyfH7dzmpmSt4gmenJO3sxGLvRMkP8fiKXjBjSppWa9vRlnGfd FwPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685722186; x=1688314186; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=iiQKR5r12cEmfxEtqKB501qQ7U5/inaqlNqkSHrg1Dk=; b=VV0aZNM0He5OoOzoAi7L9gqfHVrm2RPmCuF3ovNucFNsAnjbmeNaj+fEVbWIIZ1cnx R5V5lRiQrI3dVmOiV9l9ZvzUDw/5jp3ijkYWmMtmlusNr5l1iylntIBXGPwXELeldGzx yokH4QbvqTkaQqnwOdSy+aRFt1nZP12cEJ7ezkqFC5+s9uq2YyHJWVRNZMNofGRPYmDJ Ecz+DCzSkEAC2lhT37yO0vkmO2g7W8b4WK5ayaQPHR+2BpwaQFWNt4l/QdhUBUtv7T/e QOd0sHmDzl+VOBOaxY4jdSYMZkZd++IJxoBc18qH/NrAHacowhMYc5K9S+iJb6YjRhcO GDeg== X-Gm-Message-State: AC+VfDyeqAkH+wZ8vVvkh+Jhw2x3CF2yIF0r7xInaRkfh80t96Nkf477 DYd48Y1ina3pD4rfR9gRhg2l3Txd0GbC X-Google-Smtp-Source: ACHHUZ4B/VNE5B0Lzqq5kfdIQx5Z2vYuoQBh8/63RZRhZfWL9mTILlGstZ7p9kQje0NOJUJPGy2sE9Fs2xL/ X-Received: from vipin.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:479f]) (user=vipinsh job=sendgmr) by 2002:a05:6902:1545:b0:ba8:181b:2558 with SMTP id r5-20020a056902154500b00ba8181b2558mr2255805ybu.4.1685722186031; Fri, 02 Jun 2023 09:09:46 -0700 (PDT) Date: Fri, 2 Jun 2023 09:09:11 -0700 In-Reply-To: <20230602160914.4011728-1-vipinsh@google.com> Mime-Version: 1.0 References: <20230602160914.4011728-1-vipinsh@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Message-ID: <20230602160914.4011728-14-vipinsh@google.com> Subject: [PATCH v2 13/16] KVM: arm64: Run clear-dirty-log under MMU read lock From: Vipin Sharma 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 --- 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, ph= ys_addr_t addr, if (ret) break; =20 - if (resched && next !=3D end) - cond_resched_rwlock_write(&kvm->mmu_lock); + if (resched && next !=3D end) { + if (flags & KVM_PGTABLE_WALK_SHARED) + cond_resched_rwlock_read(&kvm->mmu_lock); + else + cond_resched_rwlock_write(&kvm->mmu_lock); + } } while (addr =3D next, addr !=3D end); =20 return ret; @@ -1131,11 +1135,11 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct= kvm *kvm, phys_addr_t start =3D (base_gfn + __ffs(mask)) << PAGE_SHIFT; phys_addr_t end =3D (base_gfn + __fls(mask) + 1) << PAGE_SHIFT; =20 - 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); =20 + 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 --=20 2.41.0.rc0.172.g3f132b7071-goog