powerpc/eeh: Move PE tree setup into the platform

The EEH core has a concept of a "PE tree" to support PowerNV. The PE tree
follows the PCI bus structures because a reset asserted on an upstream
bridge will be propagated to the downstream bridges. On pseries there's a
1-1 correspondence between what the guest sees are a PHB and a PE so the
"tree" is really just a single node.

Current the EEH core is reponsible for setting up this PE tree which it
does by traversing the pci_dn tree. The structure of the pci_dn tree
matches the bus tree on PowerNV which leads to the PE tree being "correct"
this setup method doesn't make a whole lot of sense and it's actively
confusing for the pseries case where it doesn't really do anything.

We want to remove the dependence on pci_dn anyway so this patch move
choosing where to insert a new PE into the platform code rather than
being part of the generic EEH code. For PowerNV this simplifies the
tree building logic and removes the use of pci_dn. For pseries we
keep the existing logic. I'm not really convinced it does anything
due to the 1-1 PE-to-PHB correspondence so every device under that
PHB should be in the same PE, but I'd rather not remove it entirely
until we've had a chance to look at it more deeply.

Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200725081231.39076-14-oohall@gmail.com

1 files changed, 57 insertions, 10 deletions

diff --git a/arch/powerpc/platforms/pseries/eeh_pseries.c b/arch/powerpc/platforms/pseries/eeh_pseries.c
index 69650d8dc705..cb2d9a970b7b 100644
--- a/arch/powerpc/platforms/pseries/eeh_pseries.c
+++ b/arch/powerpc/platforms/pseries/eeh_pseries.c
@@ -69,11 +69,16 @@ void pseries_pcibios_bus_add_device(struct pci_dev *pdev)
 	pseries_eeh_init_edev(pdn);
 #ifdef CONFIG_PCI_IOV
 	if (pdev->is_virtfn) {
+		/*
+		 * FIXME: This really should be handled by choosing the right
+		 *        parent PE in in pseries_eeh_init_edev().
+		 */
+		struct eeh_pe *physfn_pe = pci_dev_to_eeh_dev(pdev->physfn)->pe;
 		struct eeh_dev *edev = pdn_to_eeh_dev(pdn);
 
 		edev->pe_config_addr =  (pdn->busno << 16) | (pdn->devfn << 8);
 		eeh_pe_tree_remove(edev); /* Remove as it is adding to bus pe */
-		eeh_pe_tree_insert(edev);   /* Add as VF PE type */
+		eeh_pe_tree_insert(edev, physfn_pe);   /* Add as VF PE type */
 	}
 #endif
 	eeh_probe_device(pdev);
@@ -386,6 +391,43 @@ static int pseries_eeh_find_ecap(struct pci_dn *pdn, int cap)
 }
 
 /**
+ * pseries_eeh_pe_get_parent - Retrieve the parent PE
+ * @edev: EEH device
+ *
+ * The whole PEs existing in the system are organized as hierarchy
+ * tree. The function is used to retrieve the parent PE according
+ * to the parent EEH device.
+ */
+static struct eeh_pe *pseries_eeh_pe_get_parent(struct eeh_dev *edev)
+{
+	struct eeh_dev *parent;
+	struct pci_dn *pdn = eeh_dev_to_pdn(edev);
+
+	/*
+	 * It might have the case for the indirect parent
+	 * EEH device already having associated PE, but
+	 * the direct parent EEH device doesn't have yet.
+	 */
+	if (edev->physfn)
+		pdn = pci_get_pdn(edev->physfn);
+	else
+		pdn = pdn ? pdn->parent : NULL;
+	while (pdn) {
+		/* We're poking out of PCI territory */
+		parent = pdn_to_eeh_dev(pdn);
+		if (!parent)
+			return NULL;
+
+		if (parent->pe)
+			return parent->pe;
+
+		pdn = pdn->parent;
+	}
+
+	return NULL;
+}
+
+/**
  * pseries_eeh_init_edev - initialise the eeh_dev and eeh_pe for a pci_dn
  *
  * @pdn: PCI device node
@@ -468,6 +510,8 @@ void pseries_eeh_init_edev(struct pci_dn *pdn)
 	if (ret) {
 		eeh_edev_dbg(edev, "EEH failed to enable on device (code %d)\n", ret);
 	} else {
+		struct eeh_pe *parent;
+
 		/* Retrieve PE address */
 		edev->pe_config_addr = pseries_eeh_get_pe_addr(pdn);
 		pe.addr = edev->pe_config_addr;
@@ -480,16 +524,19 @@ void pseries_eeh_init_edev(struct pci_dn *pdn)
 		if (ret > 0 && ret != EEH_STATE_NOT_SUPPORT)
 			enable = 1;
 
-		if (enable) {
+		/*
+		 * This device doesn't support EEH, but it may have an
+		 * EEH parent. In this case any error on the device will
+		 * freeze the PE of it's upstream bridge, so added it to
+		 * the upstream PE.
+		 */
+		parent = pseries_eeh_pe_get_parent(edev);
+		if (parent && !enable)
+			edev->pe_config_addr = parent->addr;
+
+		if (enable || parent) {
 			eeh_add_flag(EEH_ENABLED);
-			eeh_pe_tree_insert(edev);
-		} else if (pdn->parent && pdn_to_eeh_dev(pdn->parent) &&
-			   (pdn_to_eeh_dev(pdn->parent))->pe) {
-			/* This device doesn't support EEH, but it may have an
-			 * EEH parent, in which case we mark it as supported.
-			 */
-			edev->pe_config_addr = pdn_to_eeh_dev(pdn->parent)->pe_config_addr;
-			eeh_pe_tree_insert(edev);
+			eeh_pe_tree_insert(edev, parent);
 		}
 		eeh_edev_dbg(edev, "EEH is %s on device (code %d)\n",
 			     (enable ? "enabled" : "unsupported"), ret);