Add a first pass at a way to blacklist MSI on systems where it doesn't

work:
- A new PCI quirk (PCI_QUIRK_DISABLE_MSI) is added to the quirk table.
- A new pci_msi_device_blacklisted() determines if a passed in device
  matches an MSI quirk in the quirk table.  This can be overridden (all
  quirks ignored) by setting the hw.pci.honor_msi_blacklist to 0.
- A global blacklist check is performed in the MI PCI bus code by checking
  to see if the device at 0:0:0 is blacklisted.

Tested by:	jdp

2 files changed, 52 insertions, 0 deletions

diff --git a/sys/dev/pci/pci.c b/sys/dev/pci/pci.c
index c6d16e3..44247b45 100644
--- a/sys/dev/pci/pci.c
+++ b/sys/dev/pci/pci.c
@@ -165,6 +165,7 @@ struct pci_quirk {
 	uint32_t devid;	/* Vendor/device of the card */
 	int	type;
 #define	PCI_QUIRK_MAP_REG	1 /* PCI map register in weird place */
+#define	PCI_QUIRK_DISABLE_MSI	2 /* MSI/MSI-X doesn't work */
 	int	arg1;
 	int	arg2;
 };
@@ -224,6 +225,11 @@ TUNABLE_INT("hw.pci.enable_msix", &pci_do_msix);
 SYSCTL_INT(_hw_pci, OID_AUTO, enable_msix, CTLFLAG_RW, &pci_do_msix, 1,
     "Enable support for MSI-X interrupts");
 
+static int pci_honor_msi_blacklist = 1;
+TUNABLE_INT("hw.pci.honor_msi_blacklist", &pci_honor_msi_blacklist);
+SYSCTL_INT(_hw_pci, OID_AUTO, honor_msi_blacklist, CTLFLAG_RD,
+    &pci_honor_msi_blacklist, 1, "Honor chipset blacklist for MSI");
+
 /* Find a device_t by bus/slot/function */
 
 device_t
@@ -1195,6 +1201,47 @@ pci_resume_msi(device_t dev)
 }
 
 /*
+ * Returns true if the specified device is blacklisted because MSI
+ * doesn't work.
+ */
+int
+pci_msi_device_blacklisted(device_t dev)
+{
+	struct pci_quirk *q;
+
+	if (!pci_honor_msi_blacklist)
+		return (0);
+
+	for (q = &pci_quirks[0]; q->devid; q++) {
+		if (q->devid == pci_get_devid(dev) &&
+		    q->type == PCI_QUIRK_DISABLE_MSI)
+			return (1);
+	}
+	return (0);
+}
+
+/*
+ * Determine if MSI is blacklisted globally on this sytem.  Currently,
+ * we just check for blacklisted chipsets as represented by the
+ * host-PCI bridge at device 0:0:0.  In the future, it may become
+ * necessary to check other system attributes, such as the kenv values
+ * that give the motherboard manufacturer and model number.
+ */
+static int
+pci_msi_blacklisted(void)
+{
+	device_t dev;
+
+	if (!pci_honor_msi_blacklist)
+		return (0);
+
+	dev = pci_find_bsf(0, 0, 0);
+	if (dev != NULL)
+		return (pci_msi_device_blacklisted(dev));
+	return (0);
+}
+
+/*
  * Attempt to allocate *count MSI messages.  The actual number allocated is
  * returned in *count.  After this function returns, each message will be
  * available to the driver as SYS_RES_IRQ resources starting at a rid 1.
@@ -1217,6 +1264,10 @@ pci_alloc_msi_method(device_t dev, device_t child, int *count)
 	if (rle != NULL && rle->res != NULL)
 		return (ENXIO);
 
+	/* If MSI is blacklisted for this system, fail. */
+	if (pci_msi_blacklisted())
+		return (ENXIO);
+
 	/* Try MSI-X first. */
 	error = pci_alloc_msix(dev, child, count);
 	if (error != ENODEV)
diff --git a/sys/dev/pci/pcivar.h b/sys/dev/pci/pcivar.h
index 846f99a..eca13ef 100644
--- a/sys/dev/pci/pcivar.h
+++ b/sys/dev/pci/pcivar.h
@@ -417,6 +417,7 @@ void	pci_enable_msix(device_t dev, u_int index, uint64_t address,
 void	pci_mask_msix(device_t dev, u_int index);
 int	pci_pending_msix(device_t dev, u_int index);
 void	pci_unmask_msix(device_t dev, u_int index);
+int	pci_msi_device_blacklisted(device_t dev);
 
 #endif	/* _SYS_BUS_H_ */