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Date:   Thu, 9 Aug 2018 11:02:08 +0200
From:   Jan Kara <jack@suse.cz>
To:     Zhang Yi <yi.z.zhang@linux.intel.com>
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-nvdimm@lists.01.org, pbonzini@redhat.com,
        dan.j.williams@intel.com, jack@suse.cz, hch@lst.de,
        yu.c.zhang@intel.com, linux-mm@kvack.org, rkrcmar@redhat.com,
        yi.z.zhang@intel.com
Subject: Re: [PATCH V3 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio
Message-ID: <20180809090208.GD5069@quack2.suse.cz>
References: <cover.1533811181.git.yi.z.zhang@linux.intel.com>
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On Thu 09-08-18 18:52:48, 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.
> 
> V1:
> https://lkml.org/lkml/2018/7/4/91
> 
> V2:
> https://lkml.org/lkml/2018/7/10/135
> 
> V3:
> [PATCH V3 1/4] Needs Comments.
> [PATCH V3 2/4] Update the description of MEMORY_DEVICE_DEV_DAX: Jan
> [PATCH V3 3/4] Acked-by: Jan in V2

Hum, but it is not the the patch...

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR