[Skiboot] [PATCH] eeh: Fix eeh event handling

[Alistair Popple]

The opal eeh interrupt handlers raise an opal event
(OPAL_EVENT_PCI_ERROR) whenever there is some processing required from
the OS. The OS then needs to call opal_pci_next_error(...) in a loop
passing each phb in turn to clear the event.

However opal_pci_next_error(...) clears the event unconditionally
meaning it would be possible for eeh events to be cleared without
processing them leading to missed events.

This patch fixes the problem by keeping track of eeh events on a
per-phb basis and only clearing the opal event once all phb eeh events
have been cleared.

Signed-off-by: Alistair Popple <alistair at popple.id.au>
---
 core/pci-opal.c | 23 +++++++++++++++++++++--
 core/pci.c      |  2 ++
 hw/p7ioc-phb.c  |  2 +-
 hw/p7ioc.c      |  7 +++++--
 include/pci.h   |  3 +++
 5 files changed, 32 insertions(+), 5 deletions(-)

diff --git a/core/pci-opal.c b/core/pci-opal.c
index a1c6e7a..75c689e 100644
--- a/core/pci-opal.c
+++ b/core/pci-opal.c
@@ -53,6 +53,26 @@ opal_call(OPAL_PCI_CONFIG_WRITE_BYTE, opal_pci_config_write_byte, 4);
 opal_call(OPAL_PCI_CONFIG_WRITE_HALF_WORD, opal_pci_config_write_half_word, 4);
 opal_call(OPAL_PCI_CONFIG_WRITE_WORD, opal_pci_config_write_word, 4);
 
+static struct lock opal_eeh_evt_lock = LOCK_UNLOCKED;
+static uint64_t opal_eeh_evt = 0;
+
+void opal_pci_eeh_set_evt(uint64_t phb_id)
+{
+	lock(&opal_eeh_evt_lock);
+	opal_eeh_evt |= 1ULL << phb_id;
+	opal_update_pending_evt(OPAL_EVENT_PCI_ERROR, OPAL_EVENT_PCI_ERROR);
+	unlock(&opal_eeh_evt_lock);
+}
+
+void opal_pci_eeh_clear_evt(uint64_t phb_id)
+{
+	lock(&opal_eeh_evt_lock);
+	opal_eeh_evt &= ~(1ULL << phb_id);
+	if (!opal_eeh_evt)
+		opal_update_pending_evt(OPAL_EVENT_PCI_ERROR, 0);
+	unlock(&opal_eeh_evt_lock);
+}
+
 static int64_t opal_pci_eeh_freeze_status(uint64_t phb_id, uint64_t pe_number,
 					  uint8_t *freeze_state,
 					  uint16_t *pci_error_type,
@@ -660,8 +680,7 @@ static int64_t opal_pci_next_error(uint64_t phb_id, uint64_t *first_frozen_pe,
 		return OPAL_UNSUPPORTED;
 	phb->ops->lock(phb);
 
-	/* Any call to this function clears the error event */
-	opal_update_pending_evt(OPAL_EVENT_PCI_ERROR, 0);
+	opal_pci_eeh_clear_evt(phb_id);
 	rc = phb->ops->next_error(phb, first_frozen_pe, pci_error_type,
 				  severity);
 	phb->ops->unlock(phb);
diff --git a/core/pci.c b/core/pci.c
index 5d97d4b..0b7dd64 100644
--- a/core/pci.c
+++ b/core/pci.c
@@ -21,6 +21,8 @@
 #include <timebase.h>
 #include <device.h>
 
+/* The eeh event code will need updating if this is ever increased to
+ * support more than 64 phbs */
 static struct phb *phbs[64];
 
 #define PCITRACE(_p, _bdfn, fmt, a...) \
diff --git a/hw/p7ioc-phb.c b/hw/p7ioc-phb.c
index d84fd15..89592c4 100644
--- a/hw/p7ioc-phb.c
+++ b/hw/p7ioc-phb.c
@@ -2740,7 +2740,7 @@ static void p7ioc_phb_err_interrupt(void *data, uint32_t isn)
 
 	PHBDBG(p, "Got interrupt 0x%04x\n", isn);
 
-	opal_update_pending_evt(OPAL_EVENT_PCI_ERROR, OPAL_EVENT_PCI_ERROR);
+	opal_pci_eeh_set_evt(p->phb.opal_id);
 
 	/* If the PHB is broken, go away */
 	if (p->state == P7IOC_PHB_STATE_BROKEN)
diff --git a/hw/p7ioc.c b/hw/p7ioc.c
index 2315e81..48a9dc9 100644
--- a/hw/p7ioc.c
+++ b/hw/p7ioc.c
@@ -575,8 +575,11 @@ static void p7ioc_rgc_interrupt(void *data, uint32_t isn)
 
 	/* We will notify OS while getting error from GEM */
 	if (p7ioc_check_GEM(ioc))
-		opal_update_pending_evt(OPAL_EVENT_PCI_ERROR,
-					OPAL_EVENT_PCI_ERROR);
+		/* This is a bit hacky but works - we raise the event
+		on a downstream phb as the OS needs to call
+		opal_pci_next_error for all phbs to ensure all events
+		are cleared anyway. */
+		opal_pci_eeh_set_evt(ioc->phbs[0].phb.opal_id);
 }
 
 static const struct irq_source_ops p7ioc_rgc_irq_ops = {
diff --git a/include/pci.h b/include/pci.h
index 9573961..6b3a228 100644
--- a/include/pci.h
+++ b/include/pci.h
@@ -511,4 +511,7 @@ extern void pci_std_swizzle_irq_map(struct dt_node *dt_node,
 extern void pci_init_slots(void);
 extern void pci_reset(void);
 
+extern void opal_pci_eeh_set_evt(uint64_t phb_id);
+extern void opal_pci_eeh_clear_evt(uint64_t phb_id);
+
 #endif /* __PCI_H */
-- 
1.8.3.2