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 55344CCFA13 for ; Thu, 30 Apr 2026 11:15:34 +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: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=AqcFoG67GT0Pu06Ylm/Ut8xhZJ5l6cBlXaAvHH2/Jcc=; b=K1cMoa7fWDKQNZDdLTbuK59NYc 1qwRsKBgIy+BLEeqQEo8LLeB/yM3tX6jRuZ6ZNGvYSG2AlcAAHaqNoRUwXdqxqDnlYyISEEKGRnnR jrvN1a/ogTOTcma0nEdfoLVelpBZRPkIvOXj2RU85vGDvq+tD6qEb1a/sA75o7meTshgKgdQ7VG04 3ARkf9UAF/ZL3JRVcLR3LpI5kNlP9x9nhoN7xg5tICGRlA6X1ROLa166EYXYTqaKC4VLHHOti5OtX iafKCKxTN6J62pJMuHbCUJjwipso8kSwu9aAKyMIUvrOdReSC/zryX4gVXID56EL7vbiy6Kxvdlvb YBXCWKpw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1wIPMg-00000005L8U-2lti; Thu, 30 Apr 2026 11:15:30 +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 1wIPMa-00000005L4r-1C1A for linux-arm-kernel@lists.infradead.org; Thu, 30 Apr 2026 11:15:25 +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 32AF13311; Thu, 30 Apr 2026 04:15:18 -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 37C233F763; Thu, 30 Apr 2026 04:15:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1777547723; bh=BxOAhxaI3ep0pCLZHvFXFWhljUjYRpulIZeDdhTGMx0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tW6C+0X8vWRpU3tueo+qCaEfYKtSSWq3qISrRQm4ow8VE9Xc/V868i7jDfltdB2Wa W4LAqThuXJkL6IDVuGj4WbH6zdbCygpLtMzu87JLzao4jj2Vh3q+EO/fhzFl/y7ncK LYWyKsSrgT7UthhHo3POxnaq9EpFRZiy1RBSCdHs= From: Leonardo Bras To: Catalin Marinas , Will Deacon , Leonardo Bras , Marc Zyngier , Oliver Upton , Joey Gouly , Suzuki K Poulose , Zenghui Yu , "Rafael J. Wysocki" , Len Brown , Saket Dumbre , Paolo Bonzini , Chengwen Feng , Jonathan Cameron , Kees Cook , =?UTF-8?q?Miko=C5=82aj=20Lenczewski?= , Ryan Roberts , Yang Shi , Thomas Huth , mrigendrachaubey , Yeoreum Yun , Mark Brown , Kevin Brodsky , James Clark , Ard Biesheuvel , Fuad Tabba , Raghavendra Rao Ananta , Nathan Chancellor , Vincent Donnefort , Lorenzo Pieralisi , Sascha Bischoff , Anshuman Khandual , Tian Zheng , Wei-Lin Chang Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-acpi@vger.kernel.org, acpica-devel@lists.linux.dev, kvm@vger.kernel.org Subject: [PATCH v1 01/12] KVM: arm64: Enable eager hugepage splitting if HDBSS is available Date: Thu, 30 Apr 2026 12:14:05 +0100 Message-ID: <20260430111424.3479613-3-leo.bras@arm.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260430111424.3479613-2-leo.bras@arm.com> References: <20260430111424.3479613-2-leo.bras@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260430_041524_470629_87093F36 X-CRM114-Status: GOOD ( 13.22 ) 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 d089c107d9b7..42c734423253 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: -- 2.54.0