Re: [PATCH v3 16/16] cxl/pci: Rightsize CDAT response allocation

[Alexey Kardashevskiy <aik@amd.com>]

On 11/2/23 07:25, Lukas Wunner wrote:
> Jonathan notes that cxl_cdat_get_length() and cxl_cdat_read_table()
> allocate 32 dwords for the DOE response even though it may be smaller.
> 
> In the case of cxl_cdat_get_length(), only the second dword of the
> response is of interest (it contains the length).  So reduce the
> allocation to 2 dwords and let DOE discard the remainder.
> 
> In the case of cxl_cdat_read_table(), a correctly sized allocation for
> the full CDAT already exists.  Let DOE write each table entry directly
> into that allocation.  There's a snag in that the table entry is
> preceded by a Table Access Response Header (1 dword).  Save the last
> dword of the previous table entry, let DOE overwrite it with the
> header of the next entry and restore it afterwards.
> 
> The resulting CDAT is preceded by 4 unavoidable useless bytes.  Increase
> the allocation size accordingly and skip these bytes when exposing CDAT
> in sysfs.
> 
> The buffer overflow check in cxl_cdat_read_table() becomes unnecessary
> because the remaining bytes in the allocation are tracked in "length",
> which is passed to DOE and limits how many bytes it writes to the
> allocation.  Additionally, cxl_cdat_read_table() bails out if the DOE
> response is truncated due to insufficient space.
> 
> Tested-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: Lukas Wunner <lukas@wunner.de>
> Cc: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> ---
>   Changes v2 -> v3:
>   * Newly added patch in v3 on popular request (Jonathan)
> 
>   drivers/cxl/core/pci.c | 34 ++++++++++++++++++----------------


Almost no change from this patchset applied cleanly to 
drivers/cxl/core/pci.c, what is the patchset based on? Thanks,

-- 
Alexey