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SubjectRe: [PATCH V5 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio

Hello Yi,

> Any comments?
>
> Hi Pankaj and Paolo,

I am just helping with the review. Paolo & Dan probably will decide.

Thanks,
Pankaj

>
> Can we Queue this to merge list since there no other comments last 2
> weeks?
>
> Regards
> Yi.
>
> On 2018-09-08 at 02:03:02 +0800, 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:
> > https://lkml.org/lkml/2018/8/9/17
> >
> > V4:
> > https://lkml.org/lkml/2018/8/22/17
> >
> > V5:
> > [PATCH V3 1/4] Reviewed-by: David / Acked-by: Pankaj
> > [PATCH V3 2/4] Reviewed-by: Jan
> > [PATCH V3 3/4] Acked-by: Jan
> > [PATCH V3 4/4] Added "Acked-by: Pankaj", Added in-line comments: Dave
> >
> > 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 | 8 ++++++++
> > include/linux/mm.h | 12 ++++++++++++
> > virt/kvm/kvm_main.c | 24 ++++++++++++++++--------
> > 4 files changed, 37 insertions(+), 8 deletions(-)
> >
> > --
> > 2.7.4
> >
>

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