From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 05A2C6B0005 for ; Thu, 5 Jul 2018 01:33:29 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id 70-v6so1260149plc.1 for ; Wed, 04 Jul 2018 22:33:28 -0700 (PDT) Received: from mga14.intel.com (mga14.intel.com. [192.55.52.115]) by mx.google.com with ESMTPS id e17-v6si4531536pgv.160.2018.07.04.22.33.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 04 Jul 2018 22:33:27 -0700 (PDT) Subject: Re: [PATCH 3/3] kvm: add a function to check if page is from NVDIMM pmem. References: <359fdf0103b61014bf811d88d4ce36bc793d18f2.1530716899.git.yi.z.zhang@linux.intel.com> <1efab832-8782-38f3-9fd5-7a8b45bde153@redhat.com> From: "Zhang,Yi" Message-ID: Date: Thu, 5 Jul 2018 21:19:30 +0800 MIME-Version: 1.0 In-Reply-To: <1efab832-8782-38f3-9fd5-7a8b45bde153@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, dan.j.williams@intel.com, jack@suse.cz, hch@lst.de, yu.c.zhang@intel.com Cc: linux-mm@kvack.org, rkrcmar@redhat.com, yi.z.zhang@intel.com On 2018a1'07ae??04ae?JPY 23:25, Paolo Bonzini wrote: > On 04/07/2018 17:30, Zhang Yi wrote: >> 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 indentify 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 >> Signed-off-by: Zhang Yu >> --- >> virt/kvm/kvm_main.c | 17 +++++++++++++++-- >> 1 file changed, 15 insertions(+), 2 deletions(-) >> >> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >> index afb2e6e..1365d18 100644 >> --- a/virt/kvm/kvm_main.c >> +++ b/virt/kvm/kvm_main.c >> @@ -140,10 +140,23 @@ __weak void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, >> { >> } >> >> +static bool kvm_is_nd_pfn(kvm_pfn_t pfn) >> +{ >> + struct page *page = pfn_to_page(pfn); >> + >> + return is_zone_device_page(page) && >> + ((page->pgmap->type == MEMORY_DEVICE_FS_DAX) || >> + (page->pgmap->type == MEMORY_DEVICE_DEV_DAX)); >> +} > If the mm people agree, I'd prefer something that takes a struct page * > and is exported by include/linux/mm.h. Then KVM can just do something like > > struct page *page; > if (!pfn_valid(pfn)) > return true; > > page = pfn_to_page(pfn); > return PageReserved(page) && !is_dax_page(page); > > Thanks, > > Paolo Yeah, that could be much better. Thanks for your comments Paolo. Hi Kara, Do u have Any opinions/ideas to add such definition in mm? Regards, Yi