cxl/core/port: Handle invalid decoders

In case init_hdm_decoder() finds invalid settings, skip to the next
valid decoder. Only fail port enumeration if zero valid decoders are
found. This protects the driver init against broken hardware and / or
future interleave capabilities.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164317464918.3438644.12371149695618136198.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index 05b0b292e72d873aa94f67892c46d896a0eee3a2..0e89a7a932d40e18f92be92d3fb0f7a983f9a5dc 100644 (file)
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -149,8 +149,8 @@ static int to_interleave_ways(u32 ctrl)
        }
 }
 
-static void init_hdm_decoder(struct cxl_decoder *cxld, int *target_map,
-                            void __iomem *hdm, int which)
+static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
+                           int *target_map, void __iomem *hdm, int which)
 {
        u64 size, base;
        u32 ctrl;
@@ -166,6 +166,11 @@ static void init_hdm_decoder(struct cxl_decoder *cxld, int *target_map,
 
        if (!(ctrl & CXL_HDM_DECODER0_CTRL_COMMITTED))
                size = 0;
+       if (base == U64_MAX || size == U64_MAX) {
+               dev_warn(&port->dev, "decoder%d.%d: Invalid resource range\n",
+                        port->id, cxld->id);
+               return -ENXIO;
+       }
 
        cxld->decoder_range = (struct range) {
                .start = base,
@@ -179,6 +184,12 @@ static void init_hdm_decoder(struct cxl_decoder *cxld, int *target_map,
                        cxld->flags |= CXL_DECODER_F_LOCK;
        }
        cxld->interleave_ways = to_interleave_ways(ctrl);
+       if (!cxld->interleave_ways) {
+               dev_warn(&port->dev,
+                        "decoder%d.%d: Invalid interleave ways (ctrl: %#x)\n",
+                        port->id, cxld->id, ctrl);
+               return -ENXIO;
+       }
        cxld->interleave_granularity = to_interleave_granularity(ctrl);
 
        if (FIELD_GET(CXL_HDM_DECODER0_CTRL_TYPE, ctrl))
@@ -187,12 +198,14 @@ static void init_hdm_decoder(struct cxl_decoder *cxld, int *target_map,
                cxld->target_type = CXL_DECODER_ACCELERATOR;
 
        if (is_cxl_endpoint(to_cxl_port(cxld->dev.parent)))
-               return;
+               return 0;
 
        target_list.value =
                ioread64_hi_lo(hdm + CXL_HDM_DECODER0_TL_LOW(which));
        for (i = 0; i < cxld->interleave_ways; i++)
                target_map[i] = target_list.target_id[i];
+
+       return 0;
 }
 
 /**
@@ -203,7 +216,7 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm)
 {
        void __iomem *hdm = cxlhdm->regs.hdm_decoder;
        struct cxl_port *port = cxlhdm->port;
-       int i, committed;
+       int i, committed, failed;
        u32 ctrl;
 
        /*
@@ -223,7 +236,7 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm)
        if (committed != cxlhdm->decoder_count)
                msleep(20);
 
-       for (i = 0; i < cxlhdm->decoder_count; i++) {
+       for (i = 0, failed = 0; i < cxlhdm->decoder_count; i++) {
                int target_map[CXL_DECODER_MAX_INTERLEAVE] = { 0 };
                int rc, target_count = cxlhdm->target_count;
                struct cxl_decoder *cxld;
@@ -238,7 +251,13 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm)
                        return PTR_ERR(cxld);
                }
 
-               init_hdm_decoder(cxld, target_map, cxlhdm->regs.hdm_decoder, i);
+               rc = init_hdm_decoder(port, cxld, target_map,
+                                     cxlhdm->regs.hdm_decoder, i);
+               if (rc) {
+                       put_device(&cxld->dev);
+                       failed++;
+                       continue;
+               }
                rc = add_hdm_decoder(port, cxld, target_map);
                if (rc) {
                        dev_warn(&port->dev,
@@ -247,6 +266,11 @@ int devm_cxl_enumerate_decoders(struct cxl_hdm *cxlhdm)
                }
        }
 
+       if (failed == cxlhdm->decoder_count) {
+               dev_err(&port->dev, "No valid decoders found\n");
+               return -ENXIO;
+       }
+
        return 0;
 }
 EXPORT_SYMBOL_NS_GPL(devm_cxl_enumerate_decoders, CXL);