Messages in this thread | | | Date | Tue, 1 Mar 2022 10:13:51 -0800 | From | Ira Weiny <> | Subject | Re: [PATCH V8 42/44] dax: Stray access protection for dax_direct_access() |
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On Thu, Feb 03, 2022 at 09:19:58PM -0800, Dan Williams wrote: > On Thu, Jan 27, 2022 at 9:55 AM <ira.weiny@intel.com> wrote: > > > > From: Ira Weiny <ira.weiny@intel.com> > > > > dax_direct_access() provides a way to obtain the direct map address of > > PMEM memory. Coordinate PKS protection with dax_direct_access() of > > protected devmap pages. > > > > Introduce 3 new dax_operation calls .map_protected .mk_readwrite and > > .mk_noaccess. These 3 calls do not have to be implemented by the dax > > provider if no protection is implemented. > > > > Threads of execution can use dax_mk_{readwrite,noaccess}() to relax the > > protection of the dax device and allow direct use of the kaddr returned > > from dax_direct_access(). The dax_mk_{readwrite,noaccess}() calls only > > need to be used to guard actual access to the memory. Other uses of > > dax_direct_access() do not need to use these guards. > > > > For users who require a permanent address to the dax device such as the > > DM write cache. dax_map_protected() indicates that the dax device has > > additional protections and that user should create it's own permanent > > mapping of the memory. Update the DM write cache code to create this > > permanent mapping. > > > > Signed-off-by: Ira Weiny <ira.weiny@intel.com> > [..] > > diff --git a/include/linux/dax.h b/include/linux/dax.h > > index 9fc5f99a0ae2..261af298f89f 100644 > > --- a/include/linux/dax.h > > +++ b/include/linux/dax.h > > @@ -30,6 +30,10 @@ struct dax_operations { > > sector_t, sector_t); > > /* zero_page_range: required operation. Zero page range */ > > int (*zero_page_range)(struct dax_device *, pgoff_t, size_t); > > + > > + bool (*map_protected)(struct dax_device *dax_dev); > > + void (*mk_readwrite)(struct dax_device *dax_dev); > > + void (*mk_noaccess)(struct dax_device *dax_dev); > > So the dax code just recently jettisoned -the >copy_{to,from}_iter() > ops and it would be shame to grow more ops. Given that the > implementation is pgmap generic I think all that is needed is way to > go from a daxdev to a pgmap and then use the pgmap helpers directly > rather than indirecting through the pmem driver just to get the pgmap.
Ok done.
dax_device now has knowledge of the pgmap which was pretty clean.
Ira
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