@@ -219,6 +219,7 @@ struct irq_domain *irq_domain_add_legacy(struct device_node *of_node,
void *host_data);
extern struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec,
enum irq_domain_bus_token bus_token);
+extern bool irq_domain_check_msi_remap(void);
extern void irq_set_default_host(struct irq_domain *host);
extern int irq_domain_alloc_descs(int virq, unsigned int nr_irqs,
irq_hw_number_t hwirq, int node,
@@ -491,6 +492,10 @@ static inline struct irq_domain *irq_find_matching_fwnode(
{
return NULL;
}
+static inline bool irq_domain_check_msi_remap(void)
+{
+ return false;
+}
#endif /* !CONFIG_IRQ_DOMAIN */
#endif /* _LINUX_IRQDOMAIN_H */
@@ -278,6 +278,30 @@ struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec,
EXPORT_SYMBOL_GPL(irq_find_matching_fwspec);
/**
+ * irq_domain_check_msi_remap() - Checks whether all PCI and
+ * platform MSI irq domains implement IRQ remapping
+ */
+bool irq_domain_check_msi_remap(void)
+{
+ struct irq_domain *h;
+ bool ret = true;
+
+ mutex_lock(&irq_domain_mutex);
+ list_for_each_entry(h, &irq_domain_list, link) {
+ if (((h->bus_token & DOMAIN_BUS_PCI_MSI) ||
+ (h->bus_token & DOMAIN_BUS_PLATFORM_MSI)) &&
+ !(h->flags & IRQ_DOMAIN_FLAG_MSI_REMAP)) {
+ ret = false;
+ goto out;
+ }
+ }
+out:
+ mutex_unlock(&irq_domain_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(irq_domain_check_msi_remap);
+
+/**
* irq_set_default_host() - Set a "default" irq domain
* @domain: default domain pointer
*
This new function checks whether all platform and PCI MSI domains implement IRQ remapping. This is useful to understand whether VFIO passthrough is safe with respect to interrupts. On ARM typically an MSI controller can sit downstream to the IOMMU without preventing VFIO passthrough. As such any assigned device can write into the MSI doorbell. In case the MSI controller implements IRQ remapping, assigned devices will not be able to trigger interrupts towards the host. On the contrary, the assignment must be emphasized as unsafe with respect to interrupts. Signed-off-by: Eric Auger <eric.auger@redhat.com> --- include/linux/irqdomain.h | 5 +++++ kernel/irq/irqdomain.c | 24 ++++++++++++++++++++++++ 2 files changed, 29 insertions(+)