From a2e794895089c1356b7687e8df1fa7d224d40bb6 Mon Sep 17 00:00:00 2001 From: Robert Richter Date: Wed, 14 Jan 2026 17:48:27 +0100 Subject: cxl/atl: Lock decoders that need address translation 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 Reviewed-by: Jonathan Cameron Reviewed-by: Dave Jiang Tested-by: Gregory Price Signed-off-by: Robert Richter Reviewed-by: Dave Jiang > --- Link: https://patch.msgid.link/20260114164837.1076338-12-rrichter@amd.com Signed-off-by: Dave Jiang --- drivers/cxl/core/atl.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/cxl/core/atl.c b/drivers/cxl/core/atl.c index c36984686fb0..09d0ea1792d9 100644 --- a/drivers/cxl/core/atl.c +++ b/drivers/cxl/core/atl.c @@ -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; -- cgit v1.2.3