linux-toradex.git/drivers/xen, branch v5.15-rc2

Merge tag 'for-linus-5.15b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2021-09-17T15:31:49+00:00

Pull xen fixes from Juergen Gross:

 - The first hunk of a Xen swiotlb fixup series fixing multiple minor
   issues and doing some small cleanups

 - Some further Xen related fixes avoiding WARN() splats when running as
   Xen guests or dom0

 - A Kconfig fix allowing the pvcalls frontend to be built as a module

* tag 'for-linus-5.15b-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  swiotlb-xen: drop DEFAULT_NSLABS
  swiotlb-xen: arrange to have buffer info logged
  swiotlb-xen: drop leftover __ref
  swiotlb-xen: limit init retries
  swiotlb-xen: suppress certain init retries
  swiotlb-xen: maintain slab count properly
  swiotlb-xen: fix late init retry
  swiotlb-xen: avoid double free
  xen/pvcalls: backend can be a module
  xen: fix usage of pmd_populate in mremap for pv guests
  xen: reset legacy rtc flag for PV domU
  PM: base: power: don't try to use non-existing RTC for storing data
  xen/balloon: use a kernel thread instead a workqueue

swiotlb-xen: drop DEFAULT_NSLABS

2021-09-15T06:42:04+00:00

It was introduced by 4035b43da6da ("xen-swiotlb: remove xen_set_nslabs")
and then not removed by 2d29960af0be ("swiotlb: dynamically allocate
io_tlb_default_mem").

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/15259326-209a-1d11-338c-5018dc38abe8@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: arrange to have buffer info logged

2021-09-15T06:42:04+00:00

I consider it unhelpful that address and size of the buffer aren't put
in the log file; it makes diagnosing issues needlessly harder. The
majority of callers of swiotlb_init() also passes 1 for the "verbose"
parameter.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/2e3c8e68-36b2-4ae9-b829-bf7f75d39d47@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: drop leftover __ref

2021-09-15T06:42:04+00:00

Commit a98f565462f0 ("xen-swiotlb: split xen_swiotlb_init") should not
only have added __init to the split off function, but also should have
dropped __ref from the one left.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/7cd163e1-fe13-270b-384c-2708e8273d34@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: limit init retries

2021-09-15T06:42:04+00:00

Due to the use of max(1024, ...) there's no point retrying (and issuing
bogus log messages) when the number of slabs is already no larger than
this minimum value.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/984fa426-2b7b-4b77-5ce8-766619575b7f@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: suppress certain init retries

2021-09-15T06:42:04+00:00

Only on the 2nd of the paths leading to xen_swiotlb_init()'s "error"
label it is useful to retry the allocation; the first one did already
iterate through all possible order values.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 
Link: https://lore.kernel.org/r/56477481-87da-4962-9661-5e1b277efde0@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: maintain slab count properly

2021-09-15T06:42:04+00:00

Generic swiotlb code makes sure to keep the slab count a multiple of the
number of slabs per segment. Yet even without checking whether any such
assumption is made elsewhere, it is easy to see that xen_swiotlb_fixup()
might alter unrelated memory when calling xen_create_contiguous_region()
for the last segment, when that's not a full one - the function acts on
full order-N regions, not individual pages.

Align the slab count suitably when halving it for a retry. Add a build
time check and a runtime one. Replace the no longer useful local
variable "slabs" by an "order" one calculated just once, outside of the
loop. Re-use "order" for calculating "dma_bits", and change the type of
the latter as well as the one of "i" while touching this anyway.

Signed-off-by: Jan Beulich 
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/dc054cb0-bec4-4db0-fc06-c9fc957b6e66@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: fix late init retry

2021-09-15T06:42:04+00:00

The commit referenced below removed the assignment of "bytes" from
xen_swiotlb_init() without - like done for xen_swiotlb_init_early() -
adding an assignment on the retry path, thus leading to excessively
sized allocations upon retries.

Fixes: 2d29960af0be ("swiotlb: dynamically allocate io_tlb_default_mem")
Signed-off-by: Jan Beulich 
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/778299d6-9cfd-1c13-026e-25ee5d14ecb3@suse.com
Signed-off-by: Juergen Gross

swiotlb-xen: avoid double free

2021-09-15T06:42:04+00:00

Of the two paths leading to the "error" label in xen_swiotlb_init() one
didn't allocate anything, while the other did already free what was
allocated.

Fixes: b82776005369 ("xen/swiotlb: Use the swiotlb_late_init_with_tbl to init Xen-SWIOTLB late when PV PCI is used")
Signed-off-by: Jan Beulich 
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig 

Link: https://lore.kernel.org/r/ce9c2adb-8a52-6293-982a-0d6ece943ac6@suse.com
Signed-off-by: Juergen Gross

xen/pvcalls: backend can be a module

2021-09-15T06:42:04+00:00

It's not clear to me why only the frontend has been tristate. Switch the
backend to be, too.

Signed-off-by: Jan Beulich 
Acked-by: Stefano Stabellini 

Link: https://lore.kernel.org/r/54a6070c-92bb-36a3-2fc0-de9ccca438c5@suse.com
Signed-off-by: Juergen Gross