cxl: Do not create vPHB if there are no AFU configuration records

The vPHB model of the cxl kernel API is a hierarchy where the AFU is
represented by the vPHB, and it's AFU configuration records are exposed
as functions under that vPHB. If there are no AFU configuration records
we will create a vPHB with nothing under it, which is a waste of
resources and will opt us into EEH handling despite not having anything
special to handle.

This also does not make sense for cards using the peer model of the cxl
kernel API, where the other functions of the device are exposed via
additional peer physical functions rather than AFU configuration
records. This model will also not work with the existing EEH handling in
the cxl driver, as that is designed around the vPHB model.

Skip creating the vPHB for AFUs without any AFU configuration records,
and opt out of EEH handling for them.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index deef9c75e73af9d78723e0acf1960a7b4b94eaaf..dd7ff221288b00a061d9ac1dc41bd0f63dd82f97 100644 (file)
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -1572,6 +1572,9 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
                 */
                for (i = 0; i < adapter->slices; i++) {
                        afu = adapter->afu[i];
+                       /* Only participate in EEH if we are on a virtual PHB */
+                       if (afu->phb == NULL)
+                               return PCI_ERS_RESULT_NONE;
                        cxl_vphb_error_detected(afu, state);
                }
                return PCI_ERS_RESULT_DISCONNECT;

diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
index c8a759f4ccfaab4ca00c4c04f074e9e0f63d8424..8865e8d9b3c59ed8d774e964f898b9343689f5d2 100644 (file)
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -188,6 +188,17 @@ int cxl_pci_vphb_add(struct cxl_afu *afu)
        struct device_node *vphb_dn;
        struct device *parent;
 
+       /*
+        * If there are no AFU configuration records we won't have anything to
+        * expose under the vPHB, so skip creating one, returning success since
+        * this is still a valid case. This will also opt us out of EEH
+        * handling since we won't have anything special to do if there are no
+        * kernel drivers attached to the vPHB, and EEH handling is not yet
+        * supported in the peer model.
+        */
+       if (!afu->crs_num)
+               return 0;
+
        /* The parent device is the adapter. Reuse the device node of
         * the adapter.
         * We don't seem to care what device node is used for the vPHB,