cxl: Restore XOR'd position bits during address translation

When a device reports a DPA in events like poison, general_media,
and dram, the driver translates that DPA back to an HPA. Presently,
the CXL driver translation only considers the Modulo position and
will report the wrong HPA for XOR configured root decoders.

Add a helper function that restores the XOR'd bits during DPA->HPA
address translation. Plumb a root decoder callback to the new helper
when XOR interleave arithmetic is in use. For Modulo arithmetic, just
let the callback be NULL - as in no extra work required.

Upon completion of a DPA->HPA translation a couple of checks are
performed on the result. One simply confirms that the calculated
HPA is within the address range of the region. That test is useful
for both Modulo and XOR interleave arithmetic decodes.

A second check confirms that the HPA is within an expected chunk
based on the endpoints position in the region and the region
granularity. An XOR decode disrupts the Modulo pattern making the
chunk check useless.

To align the checks with the proper decode, pull the region range
check inline and use the helper to do the chunk check for Modulo
decodes only.

A cxl-test unit test is posted for upstream review here:
https://lore.kernel.org/20240624210644.495563-1-alison.schofield@intel.com/

Fixes: 28a3ae4ff66c ("cxl/trace: Add an HPA to cxl_poison trace events")
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Diego Garcia Rodriguez <diego.garcia.rodriguez@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/1a1ac880d9f889bd6384e657e810431b9a0a72e5.1719980933.git.alison.schofield@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

0 files changed, 0 insertions, 0 deletions