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cxl/atl: Lock decoders that need address translation

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The current kernel implementation does not support endpoint setup with
Normalized Addressing. It only translates an endpoint's DPA to the SPA
range of the host bridge. Therefore, the endpoint address range cannot
be determined, making a non-auto setup impossible. If a decoder
requires address translation, reprogramming should be disabled and the
decoder locked.

The BIOS, however, provides all the necessary address translation
data, which the kernel can use to reconfigure endpoint decoders with
normalized addresses. Locking the decoders in the BIOS would prevent a
capable kernel (or other operating systems) from shutting down
auto-generated regions and managing resources dynamically.

Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Tested-by: Gregory Price <gourry@gourry.net>
Signed-off-by: Robert Richter <rrichter@amd.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>> ---
Link: https://patch.msgid.link/20260114164837.1076338-12-rrichter@amd.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
This commit is contained in:
Robert Richter 2026-01-14 17:48:27 +01:00 committed by Dave Jiang
parent af74daf916
commit a2e7948950
1 changed files with 18 additions and 0 deletions
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18
drivers/cxl/core/atl.c
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@ -154,6 +154,24 @@ static int cxl_prm_setup_root(struct cxl_root *cxl_root, void *data)
return -ENXIO;
}
/*
* The current kernel implementation does not support endpoint
* setup with Normalized Addressing. It only translates an
* endpoint's DPA to the SPA range of the host bridge.
* Therefore, the endpoint address range cannot be determined,
* making a non-auto setup impossible. If a decoder requires
* address translation, reprogramming should be disabled and
* the decoder locked.
*
* The BIOS, however, provides all the necessary address
* translation data, which the kernel can use to reconfigure
* endpoint decoders with normalized addresses. Locking the
* decoders in the BIOS would prevent a capable kernel (or
* other operating systems) from shutting down auto-generated
* regions and managing resources dynamically.
*/
cxld->flags |= CXL_DECODER_F_LOCK;
ctx->hpa_range = hpa_range;
ctx->interleave_ways = ways;
ctx->interleave_granularity = gran;