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Fix kvm misconceives NVDIMM pages as reserved mmio

Zhang Yi kvm linux-mm linux-nvdimm lkml nvdimm 5 versions – In review

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Versions newest first · linked by author and title

  1. v5 Latest4 patches 15 repliesIn review
  2. v44 patches 6 repliesSuperseded
  3. v34 patches 12 repliesSuperseded
Earlier versions · 2
VersionPostedPatchesRepliesStatus
v24 patches7 repliesSuperseded
v13 patches7 repliesSuperseded

Changes in v5 from the cover letter

[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

Patches in v5 No applies recorded yet

#Subject and filesSizeRepliesApplied
1/4kvm: remove redundant reserved page checkvirt/kvm/kvm_main.c+2 -61 reply
2/4mm: introduce memory type MEMORY_DEVICE_DEV_DAXdrivers/dax/pmem.c include/linux/memremap.h+9 -00 replies
3/4mm: add a function to differentiate the pages is from DAX device memoryinclude/linux/mm.h+12 -00 replies
4/4kvm: add a check if pfn is from NVDIMM pmem.virt/kvm/kvm_main.c+14 -210 replies

Reviews trailers per patch

All 4 patches have a Reviewed-by or Acked-by.

PatchDavid HildenbrandPankaj GuptaJan Kara
1/4R-b A-b
2/4R-b
3/4A-b
4/4A-b

Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes. Scroll the table sideways for all 3 reviewers.

Read the v5 thread

Cover letter [PATCH V5 0/4] Fix kvm misconceives NVDIMM pages as reserved mmio

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(-)
Signature · 6 lines
2.7.4

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Read the cover letter in its thread