[PATCH] PCI: Fix pcibios_update_irq misuse of irq number

Hi Gerry,

On 28/01/15 15:21, Jiang Liu wrote:

On 2015/1/28 22:51, Marc Zyngier wrote:

quoted

pcibios_update_irq writes an irq number into the config space
of a given PCI device, but ignores the fact that this number
is a virtual interrupt number, which might be a very different
value from what the underlying hardware is using.

The obvious fix is to fetch the HW interrupt number from the
corresponding irq_data structure. This is slightly complicated
by the fact that this interrupt might be services by a stacked
domain.

This has been tested on KVM with kvmtool.

Reported-by: Lorenzo Pieralisi <redacted>
Tested-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Marc Zyngier <redacted>
---
 drivers/pci/setup-irq.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c
index 4e2d595..828cbc9 100644
--- a/drivers/pci/setup-irq.c
+++ b/drivers/pci/setup-irq.c

@@ -15,11 +15,19 @@
 #include <linux/errno.h>
 #include <linux/ioport.h>
 #include <linux/cache.h>
+#include <linux/irq.h>
 
 void __weak pcibios_update_irq(struct pci_dev *dev, int irq)
 {
-	dev_dbg(&dev->dev, "assigning IRQ %02d\n", irq);
-	pci_write_config_byte(dev, PCI_INTERRUPT_LINE, irq);
+	struct irq_data *d;
+
+	d = irq_get_irq_data(irq);
+#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
+	while (d->parent_data)
+		d = d->parent_data;
+#endif
+	dev_dbg(&dev->dev, "assigning IRQ %02ld\n", d->hwirq);
+	pci_write_config_byte(dev, PCI_INTERRUPT_LINE, d->hwirq);
 }

Hi Mark,
	Instead of modifying the common version, how about
implementing an arch specific version? Arch may have different
way to determine the irq number. Above implementation doesn't
work with x86, for example.

If you look at the Makefile, this file is used on:

obj-$(CONFIG_ALPHA) += setup-irq.o
obj-$(CONFIG_ARM) += setup-irq.o
obj-$(CONFIG_UNICORE32) += setup-irq.o
obj-$(CONFIG_SUPERH) += setup-irq.o
obj-$(CONFIG_MIPS) += setup-irq.o
obj-$(CONFIG_TILE) += setup-irq.o
obj-$(CONFIG_SPARC_LEON) += setup-irq.o
obj-$(CONFIG_M68K) += setup-irq.o

x86 doesn't use that at all.

That aside, do you know any case where this transformation would lead to
an invalid result? Worse case, irq should be equal to hwirq, shouldn't
it? Or are you thinking of something else?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...