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

From: Zhang,Yi
Date: Mon Aug 13 2018 - 05:49:58 EST

On 2018å08æ09æ 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:
>> V2:
>> 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