powerpc/eeh: Aux PE data for error log

The patch allows PE (struct eeh_pe) instance to have auxillary data,
whose size is configurable on basis of platform. For PowerNV, the
auxillary data will be used to cache PHB diag-data for that PE
(frozen PE or fenced PHB). In turn, we can retrieve the diag-data
at any later points.

It's useful for the case of VFIO PCI devices where the error log
should be cached, and then be retrieved by the guest at later point.
Also, it can avoid PHB diag-data overwritting if another frozen PE
reported and the previous diag-data isn't fetched by guest.

Signed-off-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 25 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/eeh_pe.c b/arch/powerpc/kernel/eeh_pe.c
index 77632abf6a75..00e3844525a6 100644
--- a/arch/powerpc/kernel/eeh_pe.c
+++ b/arch/powerpc/kernel/eeh_pe.c
@@ -32,9 +32,24 @@
 #include <asm/pci-bridge.h>
 #include <asm/ppc-pci.h>
 
+static int eeh_pe_aux_size = 0;
 static LIST_HEAD(eeh_phb_pe);
 
 /**
+ * eeh_set_pe_aux_size - Set PE auxillary data size
+ * @size: PE auxillary data size
+ *
+ * Set PE auxillary data size
+ */
+void eeh_set_pe_aux_size(int size)
+{
+	if (size < 0)
+		return;
+
+	eeh_pe_aux_size = size;
+}
+
+/**
  * eeh_pe_alloc - Allocate PE
  * @phb: PCI controller
  * @type: PE type
@@ -44,9 +59,16 @@ static LIST_HEAD(eeh_phb_pe);
 static struct eeh_pe *eeh_pe_alloc(struct pci_controller *phb, int type)
 {
 	struct eeh_pe *pe;
+	size_t alloc_size;
+
+	alloc_size = sizeof(struct eeh_pe);
+	if (eeh_pe_aux_size) {
+		alloc_size = ALIGN(alloc_size, cache_line_size());
+		alloc_size += eeh_pe_aux_size;
+	}
 
 	/* Allocate PHB PE */
-	pe = kzalloc(sizeof(struct eeh_pe), GFP_KERNEL);
+	pe = kzalloc(alloc_size, GFP_KERNEL);
 	if (!pe) return NULL;
 
 	/* Initialize PHB PE */
@@ -56,6 +78,8 @@ static struct eeh_pe *eeh_pe_alloc(struct pci_controller *phb, int type)
 	INIT_LIST_HEAD(&pe->child);
 	INIT_LIST_HEAD(&pe->edevs);
 
+	pe->data = (void *)pe + ALIGN(sizeof(struct eeh_pe),
+				      cache_line_size());
 	return pe;
 }