From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pankaj Gupta Subject: Re: [PATCH V4 4/4] kvm: add a check if pfn is from NVDIMM pmem. Date: Wed, 29 Aug 2018 06:15:48 -0400 (EDT) Message-ID: <380594559.7598107.1535537748154.JavaMail.zimbra@redhat.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, yu c zhang , kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-nvdimm-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, jack-AlSwsSmVLrQ@public.gmane.org, david-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, rkrcmar-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, hch-jcswGhMUV9g@public.gmane.org, yi z zhang To: Zhang Yi Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: linux-nvdimm-bounces-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org Sender: "Linux-nvdimm" List-Id: kvm.vger.kernel.org > > 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 > >