cxl/pci: Fix to record only non-zero ranges

The function cxl_dvsec_rr_decode() retrieves and records DVSEC ranges
into info->dvsec_range[], regardless of whether it is non-zero range,
and the variable info->ranges indicates the number of non-zero ranges.
However, in cxl_hdm_decode_init(), the validation for
info->dvsec_range[] occurs in a for loop that iterates based on
info->ranges. It may result in zero range to be validated but non-zero
range not be validated, in turn, the number of allowed ranges is to be
0. Address it by only record non-zero ranges.

This fix is not urgent as it requires a configuration that zeroes out
the first dvsec range while populating the second. This has not been
observed, but it is theoretically possible. If this gets picked up for
-stable, no harm done, but there is no urgency to backport.

Fixes: 560f78559006 ("cxl/pci: Retrieve CXL DVSEC memory info")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Yanfei Xu <yanfei.xu@intel.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20240828084231.1378789-2-yanfei.xu@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

diff --git a/drivers/cxl/core/pci.c b/drivers/cxl/core/pci.c
index 5e5c24eed545b6d5cde05090c02ac3aa88445e1e..075a2b2d2ea0e23c442133637e6a392a42dd43cc 100644 (file)
--- a/drivers/cxl/core/pci.c
+++ b/drivers/cxl/core/pci.c
@@ -390,10 +390,6 @@ int cxl_dvsec_rr_decode(struct device *dev, int d,
 
                size |= temp & CXL_DVSEC_MEM_SIZE_LOW_MASK;
                if (!size) {
-                       info->dvsec_range[i] = (struct range) {
-                               .start = 0,
-                               .end = CXL_RESOURCE_NONE,
-                       };
                        continue;
                }
 
@@ -411,12 +407,10 @@ int cxl_dvsec_rr_decode(struct device *dev, int d,
 
                base |= temp & CXL_DVSEC_MEM_BASE_LOW_MASK;
 
-               info->dvsec_range[i] = (struct range) {
+               info->dvsec_range[ranges++] = (struct range) {
                        .start = base,
                        .end = base + size - 1
                };
-
-               ranges++;
        }
 
        info->ranges = ranges;