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SubjectRe: [PATCH V2 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio
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On 20/07/2018 16:11, Zhang,Yi wrote:
> Added Jiang,Dave,
>
> Ping for further review, comments.

I need an Acked-by from the MM people to merge this. Jan, Dan?

Paolo

>
> Thanks All
>
> Regards
> Yi.
>
>
> On 2018年07月11日 01:01, 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:
>> *Add documentation for MEMORY_DEVICE_DEV_DAX memory type in comment block
>> *Add is_dax_page() in mm.h to differentiate the pages is from DAX device.
>> *Remove the function kvm_is_nd_pfn().
>>
>> Zhang Yi (4):
>> kvm: remove redundant reserved page check
>> mm: introduce memory type MEMORY_DEVICE_DEV_DAX
>> mm: add a function to differentiate the pages is from DAX device
>> memory
>> kvm: add a check if pfn is from NVDIMM pmem.
>>
>> drivers/dax/pmem.c | 1 +
>> include/linux/memremap.h | 9 +++++++++
>> include/linux/mm.h | 12 ++++++++++++
>> virt/kvm/kvm_main.c | 16 ++++++++--------
>> 4 files changed, 30 insertions(+), 8 deletions(-)
>>
>
>

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