[PATCH] MSI: check for BIOS assigned addresses

Daniel Yeisley
2009-03-06T16:16:26Z

When creating MSI addresses the kernel makes them up and writes them to
the hardware without first checking for what the system BIOS may have
assigned. The patch below checks for already assigned values, and
leaves them alone if they exist.

Signed-off-by: Dan Yeisley <dan.yeisley@unisys.com>

---
diff -Naurp linux-2.6.29-rc5/arch/x86/kernel/io_apic.c linux-2.6.29-rc5-dpy/arch/x86/kernel/io_apic.c
--- linux-2.6.29-rc5/arch/x86/kernel/io_apic.c 2009-02-13 18:31:30.000000000 -0500
+++ linux-2.6.29-rc5-dpy/arch/x86/kernel/io_apic.c 2009-03-04 08:25:30.000000000 -0500
@@ -3258,6 +3258,7 @@ static int msi_compose_msg(struct pci_de
struct irq_cfg *cfg;
int err;
unsigned dest;
+ struct irq_desc *desc = irq_to_desc(irq);

cfg = irq_cfg(irq);
err = assign_irq_vector(irq, cfg, TARGET_CPUS);
@@ -3265,6 +3266,8 @@ static int msi_compose_msg(struct pci_de
return err;

dest = cpu_mask_to_apicid_and(cfg->domain, TARGET_CPUS);
+
+ read_msi_msg_desc(desc, msg);

#ifdef CONFIG_INTR_REMAP
if (irq_remapped(irq)) {
@@ -3295,17 +3298,18 @@ static int msi_compose_msg(struct pci_de
} else
#endif
{
- msg->address_hi = MSI_ADDR_BASE_HI;
- msg->address_lo =
- MSI_ADDR_BASE_LO |
- ((INT_DEST_MODE == 0) ?
- MSI_ADDR_DEST_MODE_PHYSICAL:
- MSI_ADDR_DEST_MODE_LOGICAL) |
- ((INT_DELIVERY_MODE != dest_LowestPrio) ?
- MSI_ADDR_REDIRECTION_CPU:
- MSI_ADDR_REDIRECTION_LOWPRI) |
- MSI_ADDR_DEST_ID(dest);
-
+ if (!msg->address_hi && !msg->address_lo) {
+ msg->address_hi = MSI_ADDR_BASE_HI;
+ msg->address_lo =
+ MSI_ADDR_BASE_LO |
+ ((INT_DEST_MODE == 0) ?
+ MSI_ADDR_DEST_MODE_PHYSICAL:
+ MSI_ADDR_DEST_MODE_LOGICAL) |
+ ((INT_DELIVERY_MODE != dest_LowestPrio) ?
+ MSI_ADDR_REDIRECTION_CPU:
+ MSI_ADDR_REDIRECTION_LOWPRI) |
+ MSI_ADDR_DEST_ID(dest);
+ }
msg->data =
MSI_DATA_TRIGGER_EDGE |
MSI_DATA_LEVEL_ASSERT |
@@ -3440,11 +3444,13 @@ static int setup_msi_irq(struct pci_dev
int ret;
struct msi_msg msg;

+ set_irq_msi(irq, msidesc);
ret = msi_compose_msg(dev, irq, &msg);
- if (ret < 0)
+ if (ret < 0) {
+ set_irq_msi(irq, NULL);
return ret;
+ }

- set_irq_msi(irq, msidesc);
write_msi_msg(irq, &msg);

#ifdef CONFIG_INTR_REMAP