On 2020-11-02 11:56, Frank Wunderlich wrote:
looks good on bananapi-r2, no warning, pcie-card and hdd recognized
Thanks for giving it a shot. Still needs a bit of tweaking, as I expect
it to break configurations that select CONFIG_PCI_MSI_ARCH_FALLBACKS
(we have to assume that MSIs can be handled until we hit the
arch-specific
stuff).
There is also a small nit in the way we allow userspace to mess with
this flag via sysfs, and similar restrictions should probably apply.
Updated patch below.
M.
diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index d15c881e2e7e..5bb1306162c7 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -387,10 +387,20 @@ static ssize_t msi_bus_store(struct device *dev,
struct device_attribute *attr,
return count;
}
- if (val)
+ if (val) {
+ /*
+ * If there is no possibility for this bus to deal with
+ * MSIs, then allowing them to be requested would lead to
+ * the kernel complaining loudly. In this situation, don't
+ * let userspace mess things up.
+ */
+ if (!pci_bus_is_msi_capable(subordinate))
+ return -EINVAL;
+
subordinate->bus_flags &= ~PCI_BUS_FLAGS_NO_MSI;
- else
+ } else {
subordinate->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
+ }
dev_info(&subordinate->dev, "MSI/MSI-X %s for future drivers of
devices on this bus\n",
val ? "allowed" : "disallowed");
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 4289030b0fff..28861cc6435a 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -871,6 +871,8 @@ static void pci_set_bus_msi_domain(struct pci_bus
*bus)
d = pci_host_bridge_msi_domain(b);
dev_set_msi_domain(&bus->dev, d);
+ if (!pci_bus_is_msi_capable(bus))
+ bus->bus_flags |= PCI_BUS_FLAGS_NO_MSI;
}
static int pci_register_host_bridge(struct pci_host_bridge *bridge)
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 22207a79762c..6aadb863dff4 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -2333,6 +2333,12 @@ pci_host_bridge_acpi_msi_domain(struct pci_bus
*bus) { return NULL; }
static inline bool pci_pr3_present(struct pci_dev *pdev) { return
false; }
#endif
+static inline bool pci_bus_is_msi_capable(struct pci_bus *bus)
+{
+ return (IS_ENABLED(CONFIG_PCI_MSI_ARCH_FALLBACKS) ||
+ dev_get_msi_domain(&bus->dev));
+}
+
#ifdef CONFIG_EEH
static inline struct eeh_dev *pci_dev_to_eeh_dev(struct pci_dev *pdev)
{
--
Jazz is not dead. It just smells funny...
