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author | Niklas Schnelle <schnelle@linux.ibm.com> | 2023-11-28 18:22:49 +0300 |
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committer | Alexander Gordeev <agordeev@linux.ibm.com> | 2024-01-11 20:22:58 +0300 |
commit | 80df7d6af7f6d229b34cf237b2cc9024c07111cd (patch) | |
tree | fdc236d23e01eaa0f7efd56203aad489269e545b /arch/s390/mm/fault.c | |
parent | 0130a0d3a61889060e912a533e996201c4d9a2e5 (diff) | |
download | linux-80df7d6af7f6d229b34cf237b2cc9024c07111cd.tar.xz |
s390/pci: fix max size calculation in zpci_memcpy_toio()
The zpci_get_max_write_size() helper is used to determine the maximum
size a PCI store or load can use at a given __iomem address.
For the PCI block store the following restrictions apply:
1. The dst + len must not cross a 4K boundary in the (pseudo-)MMIO space
2. len must not exceed ZPCI_MAX_WRITE_SIZE
3. len must be a multiple of 8 bytes
4. The src address must be double word (8 byte) aligned
5. The dst address must be double word (8 byte) aligned
Otherwise only a normal PCI store which takes its src value from
a register can be used. For these PCI store restriction 1 still applies.
Similarly 1 also applies to PCI loads.
It turns out zpci_max_write_size() instead implements stricter
conditions which prevents PCI block stores from being used where they
can and should be used. In particular instead of conditions 4 and 5 it
wrongly enforces both dst and src to be size aligned. This indirectly
covers condition 1 but also prevents many legal PCI block stores.
On top of the functional shortcomings the zpci_get_max_write_size() is
misnamed as it is used for both read and write size calculations. Rename
it to zpci_get_max_io_size() and implement the listed conditions
explicitly.
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Fixes: cd24834130ac ("s390/pci: base support")
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
[agordeev@linux.ibm.com replaced spaces with tabs]
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Diffstat (limited to 'arch/s390/mm/fault.c')
0 files changed, 0 insertions, 0 deletions