From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id 10539210FC384 for ; Wed, 29 Aug 2018 03:15:50 -0700 (PDT) Date: Wed, 29 Aug 2018 06:15:48 -0400 (EDT) From: Pankaj Gupta Message-ID: <380594559.7598107.1535537748154.JavaMail.zimbra@redhat.com> In-Reply-To: References: Subject: Re: [PATCH V4 4/4] kvm: add a check if pfn is from NVDIMM pmem. MIME-Version: 1.0 List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-nvdimm-bounces@lists.01.org Sender: "Linux-nvdimm" To: Zhang Yi Cc: jglisse@redhat.com, yu c zhang , kvm@vger.kernel.org, linux-nvdimm@lists.01.org, jack@suse.cz, david@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, rkrcmar@redhat.com, pbonzini@redhat.com, hch@lst.de, yi z zhang List-ID: > > For device specific memory space, when we move these area of pfn to > memory zone, we will set the page reserved flag at that time, some of > these reserved for device mmio, and some of these are not, such as > NVDIMM pmem. > > Now, we map these dev_dax or fs_dax pages to kvm for DIMM/NVDIMM > backend, since these pages are reserved, the check of > kvm_is_reserved_pfn() misconceives those pages as MMIO. Therefor, we > introduce 2 page map types, MEMORY_DEVICE_FS_DAX/MEMORY_DEVICE_DEV_DAX, > to identify these pages are from NVDIMM pmem and let kvm treat these > as normal pages. > > Without this patch, many operations will be missed due to this > mistreatment to pmem pages, for example, a page may not have chance to > be unpinned for KVM guest(in kvm_release_pfn_clean), not able to be > marked as dirty/accessed(in kvm_set_pfn_dirty/accessed) etc. > > Signed-off-by: Zhang Yi > --- > virt/kvm/kvm_main.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index c44c406..969b6ca 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -147,8 +147,12 @@ __weak void > kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > { > - if (pfn_valid(pfn)) > - return PageReserved(pfn_to_page(pfn)); > + struct page *page; > + > + if (pfn_valid(pfn)) { > + page = pfn_to_page(pfn); > + return PageReserved(page) && !is_dax_page(page); > + } > > return true; > } Acked-by: Pankaj Gupta > -- > 2.7.4 > > _______________________________________________ Linux-nvdimm mailing list Linux-nvdimm@lists.01.org https://lists.01.org/mailman/listinfo/linux-nvdimm