From mboxrd@z Thu Jan 1 00:00:00 1970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 31AC5109C055 for ; Wed, 25 Mar 2026 18:20:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc: To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=yFmm1e2joJDzrblN9CkV4X7e2hjaTZalUHmbuneKN1s=; b=f3hCKHJfdDRFLTv46HKH9A2acw RRVSO0GOggWTY5dIiP4VvsgrECKrXIkXJN4A3q5UJEMYIQRSTh3jpjxp5oEHUn9eOF3xONkhHlXRm 63Iuat7lhSc2BS1FRwF3s5GpP37ATXX9Se3Vquh2ybeZVOB2KXCb93X7+FSjsMMu2HIT7DT4/4BKT FvWal98Xy/vjLtrSH3ijuo3nVgCDY1SYVWsZMgswV76/C71u1mknl3MmcN3dbPAPMf+Q/rzbQ8qCr mGC3OxGbvvB8OPoXtYGTTCpe6+iOXflGdnx9ej3Cw0kAsah+lFSO3oPdu4MyUQO5YfF/WHUIT+ojj kTh8kH5A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5SqK-000000044EO-0U73; Wed, 25 Mar 2026 18:20:36 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5SqH-000000044Dz-1rBg for linux-arm-kernel@lists.infradead.org; Wed, 25 Mar 2026 18:20:34 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A0CC51F02; Wed, 25 Mar 2026 11:20:26 -0700 (PDT) Received: from devkitleo.cambridge.arm.com (devkitleo.cambridge.arm.com [10.1.196.90]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 687383F836; Wed, 25 Mar 2026 11:20:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774462832; bh=j2/es1QhPhuq51aj/X0brAWozFW8cVd/nUY1rJQCm28=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RnRqlju//v+l8+03/0wteCA6R1iCsC1AxpJi6NyA/fWzpmNollbBo80IOtBxUXBxZ G5EG2hgtu/qJ5SgLsJ9eud5ObOxoheQ95D/hyREnHIaEvJHzxuqvDMmezCC/dm26sj AWDLdr/3IUF3rzLY+0m1k9SAPvra5hVsUBx3KeD0= From: Leonardo Bras To: Tian Zheng Cc: Leonardo Bras , maz@kernel.org, oupton@kernel.org, catalin.marinas@arm.com, corbet@lwn.net, pbonzini@redhat.com, will@kernel.org, yuzenghui@huawei.com, wangzhou1@hisilicon.com, liuyonglong@huawei.com, Jonathan.Cameron@huawei.com, yezhenyu2@huawei.com, linuxarm@huawei.com, joey.gouly@arm.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, skhan@linuxfoundation.org, suzuki.poulose@arm.com Subject: [PATCH] arm64/kvm: Enable eager hugepage splitting if HDBSS is available Date: Wed, 25 Mar 2026 18:20:27 +0000 Message-ID: X-Mailer: git-send-email 2.53.0 In-Reply-To: References: <20260225040421.2683931-1-zhengtian10@huawei.com> <20260225040421.2683931-5-zhengtian10@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260325_112033_545299_312B48F9 X-CRM114-Status: GOOD ( 13.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org FEAT_HDBSS speeds up guest memory dirty tracking by avoiding a page fault and saving the entry in a tracking structure. That may be a problem when we have guest memory backed by hugepages or transparent huge pages, as it's not possible to do on-demand hugepage splitting, relying only on eager hugepage splitting. So, at stage2 initialization, enable eager hugepage splitting with chunk = PAGE_SIZE if the system supports HDBSS. Signed-off-by: Leonardo Bras --- arch/arm64/kvm/mmu.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 070a01e53fcb..bdfa72b7c073 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -993,22 +993,26 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu, unsigned long t mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran)); if (!mmu->last_vcpu_ran) { err = -ENOMEM; goto out_destroy_pgtable; } for_each_possible_cpu(cpu) *per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1; - /* The eager page splitting is disabled by default */ - mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT; + /* The eager page splitting is disabled by default if system has no HDBSS */ + if (system_supports_hacdbs()) + mmu->split_page_chunk_size = PAGE_SIZE; + else + mmu->split_page_chunk_size = KVM_ARM_EAGER_SPLIT_CHUNK_SIZE_DEFAULT; + mmu->split_page_cache.gfp_zero = __GFP_ZERO; mmu->pgd_phys = __pa(pgt->pgd); if (kvm_is_nested_s2_mmu(kvm, mmu)) kvm_init_nested_s2_mmu(mmu); return 0; out_destroy_pgtable: -- 2.53.0