From patchwork Thu Aug 3 14:32:04 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 13340181 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 1D775EB64DD for ; Thu, 3 Aug 2023 14:33:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236282AbjHCOdx (ORCPT ); Thu, 3 Aug 2023 10:33:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44076 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236114AbjHCOdv (ORCPT ); Thu, 3 Aug 2023 10:33:51 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D64B219B0 for ; Thu, 3 Aug 2023 07:32:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1691073148; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=k5L4YtRFm7cOLJR+l6dUREkXQfCqKIU8byjm44bC064=; b=R56I+pbAQ/m33ik2DMDy+ljhLkbDyts3WYsip/DKD52QHXHPnhT39QH29H8/RXN7aVKEgv MjWpVj8HZM/ClO9PSqT5CMsvU2u0sp8WrAeOrzY7DqxM0oa+aznF+yiOs55bQJcL/v1IQV zwQJgfbGHjJ9/Jdp+t7HGldJUv1aC2c= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-318-PirLHtypPEKo3Vn7YCBa1g-1; Thu, 03 Aug 2023 10:32:24 -0400 X-MC-Unique: PirLHtypPEKo3Vn7YCBa1g-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 391A1104D516; Thu, 3 Aug 2023 14:32:23 +0000 (UTC) Received: from t14s.fritz.box (unknown [10.39.193.129]) by smtp.corp.redhat.com (Postfix) with ESMTP id A451B200B66C; Thu, 3 Aug 2023 14:32:20 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, David Hildenbrand , Andrew Morton , Linus Torvalds , liubo , Peter Xu , Matthew Wilcox , Hugh Dickins , Jason Gunthorpe , John Hubbard , Mel Gorman , Shuah Khan , Paolo Bonzini Subject: [PATCH v3 3/7] kvm: explicitly set FOLL_HONOR_NUMA_FAULT in hva_to_pfn_slow() Date: Thu, 3 Aug 2023 16:32:04 +0200 Message-ID: <20230803143208.383663-4-david@redhat.com> In-Reply-To: <20230803143208.383663-1-david@redhat.com> References: <20230803143208.383663-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org KVM is *the* case we know that really wants to honor NUMA hinting falls. As we want to stop setting FOLL_HONOR_NUMA_FAULT implicitly, set FOLL_HONOR_NUMA_FAULT whenever we might obtain pages on behalf of a VCPU to map them into a secondary MMU, and add a comment why. Do that unconditionally in hva_to_pfn_slow() when calling get_user_pages_unlocked(). kvmppc_book3s_instantiate_page(), hva_to_pfn_fast() and gfn_to_page_many_atomic() are similarly used to map pages into a secondary MMU. However, FOLL_WRITE and get_user_page_fast_only() always implicitly honor NUMA hinting faults -- as documented for FOLL_HONOR_NUMA_FAULT -- so we can limit this change to a single location for now. Don't set it in check_user_page_hwpoison(), where we really only want to check if the mapped page is HW-poisoned. We won't set it for other KVM users of get_user_pages()/pin_user_pages() * arch/powerpc/kvm/book3s_64_mmu_hv.c: not used to map pages into a secondary MMU. * arch/powerpc/kvm/e500_mmu.c: only used on shared TLB pages with userspace * arch/s390/kvm/*: s390x only supports a single NUMA node either way * arch/x86/kvm/svm/sev.c: not used to map pages into a secondary MMU. This is a preparation for making FOLL_HONOR_NUMA_FAULT no longer implicitly be set by get_user_pages() and friends. Signed-off-by: David Hildenbrand --- virt/kvm/kvm_main.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index dfbaafbe3a00..6e4f2b81541e 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2517,7 +2517,18 @@ static bool hva_to_pfn_fast(unsigned long addr, bool write_fault, static int hva_to_pfn_slow(unsigned long addr, bool *async, bool write_fault, bool interruptible, bool *writable, kvm_pfn_t *pfn) { - unsigned int flags = FOLL_HWPOISON; + /* + * When a VCPU accesses a page that is not mapped into the secondary + * MMU, we lookup the page using GUP to map it, so the guest VCPU can + * make progress. We always want to honor NUMA hinting faults in that + * case, because GUP usage corresponds to memory accesses from the VCPU. + * Otherwise, we'd not trigger NUMA hinting faults once a page is + * mapped into the secondary MMU and gets accessed by a VCPU. + * + * Note that get_user_page_fast_only() and FOLL_WRITE for now + * implicitly honor NUMA hinting faults and don't need this flag. + */ + unsigned int flags = FOLL_HWPOISON | FOLL_HONOR_NUMA_FAULT; struct page *page; int npages;