linux-kernel - Re: [PATCH V3 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio

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Message-ID: <154a783f-5aff-c910-b252-5a6a36b37907@linux.intel.com>
Date:   Tue, 14 Aug 2018 01:33:57 +0800
From:   "Zhang,Yi" <yi.z.zhang@...ux.intel.com>
To:     Jan Kara <jack@...e.cz>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-nvdimm@...ts.01.org, pbonzini@...hat.com,
        dan.j.williams@...el.com, hch@....de, yu.c.zhang@...el.com,
        linux-mm@...ck.org, rkrcmar@...hat.com, yi.z.zhang@...el.com
Subject: Re: [PATCH V3 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio



On 2018年08月09日 17:02, Jan Kara wrote:
> 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
Sorry, I missed that, will add in the next version, thanks for your review