From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by kanga.kvack.org (Postfix) with ESMTP id 145F06B6AC0 for ; Mon, 3 Dec 2018 14:25:39 -0500 (EST) Received: by mail-pg1-f198.google.com with SMTP id s27so7439656pgm.4 for ; Mon, 03 Dec 2018 11:25:39 -0800 (PST) Received: from mga07.intel.com (mga07.intel.com. [134.134.136.100]) by mx.google.com with ESMTPS id g184si15031204pfb.288.2018.12.03.11.25.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Dec 2018 11:25:37 -0800 (PST) Subject: [PATCH RFC 3/3] kvm: Add additional check to determine if a page is refcounted From: Alexander Duyck Date: Mon, 03 Dec 2018 11:25:36 -0800 Message-ID: <154386513636.27193.9038916677163713072.stgit@ahduyck-desk1.amr.corp.intel.com> In-Reply-To: <154386493754.27193.1300965403157243427.stgit@ahduyck-desk1.amr.corp.intel.com> References: <154386493754.27193.1300965403157243427.stgit@ahduyck-desk1.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: dan.j.williams@intel.com, pbonzini@redhat.com, yi.z.zhang@linux.intel.com, brho@google.com, kvm@vger.kernel.org, linux-nvdimm@lists.01.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, dave.jiang@intel.com, yu.c.zhang@intel.com, pagupta@redhat.com, david@redhat.com, jack@suse.cz, hch@lst.de, rkrcmar@redhat.com, jglisse@redhat.com The function kvm_is_refcounted_page is used primarily to determine if KVM is allowed to take a reference on the page. It was using the PG_reserved flag to determine this previously, however in the case of DAX the page has the PG_reserved flag set, but supports pinning by taking a reference on the page. As such I have updated the check to add a special case for ZONE_DEVICE pages that have the new support_refcount_pinning flag set. Signed-off-by: Alexander Duyck --- virt/kvm/kvm_main.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 5e666df5666d..2e7e9fbb67bf 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -148,8 +148,20 @@ __weak int kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, bool kvm_is_refcounted_pfn(kvm_pfn_t pfn) { - if (pfn_valid(pfn)) - return !PageReserved(pfn_to_page(pfn)); + if (pfn_valid(pfn)) { + struct page *page = pfn_to_page(pfn); + + /* + * The reference count for MMIO pages are not updated. + * Previously this was being tested for with just the + * PageReserved check, however now ZONE_DEVICE pages may + * also allow for the refcount to be updated for the sake + * of pinning the pages so use the additional check provided + * to determine if the reference count on the page can be + * used to pin it. + */ + return !PageReserved(page) || is_device_pinnable_page(page); + } return false; }