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

From: Jan Kara
Date: Thu Aug 09 2018 - 05:02:13 EST

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...

Jan Kara <jack@xxxxxxxx>