From c7b41f0af38f53e46050b56a5b0e96710097b83c Mon Sep 17 00:00:00 2001 From: Eric Auger Date: Thu, 19 Jan 2017 20:57:59 +0000 Subject: [PATCH] irqdomain: irq_domain_check_msi_remap This new function checks whether all MSI irq 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 Reviewed-by: Marc Zyngier Reviewed-by: Tomasz Nowicki Tested-by: Tomasz Nowicki Tested-by: Bharat Bhushan Signed-off-by: Will Deacon --- include/linux/irqdomain.h | 1 + kernel/irq/irqdomain.c | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h index bc2f5719dace..188eced6813e 100644 --- a/include/linux/irqdomain.h +++ b/include/linux/irqdomain.h @@ -222,6 +222,7 @@ 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, diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c index 876e13172dc8..80c4f9312187 100644 --- a/kernel/irq/irqdomain.c +++ b/kernel/irq/irqdomain.c @@ -277,6 +277,31 @@ struct irq_domain *irq_find_matching_fwspec(struct irq_fwspec *fwspec, } EXPORT_SYMBOL_GPL(irq_find_matching_fwspec); +/** + * irq_domain_check_msi_remap - Check whether all MSI irq domains implement + * IRQ remapping + * + * Return: false if any MSI irq domain does not support IRQ remapping, + * true otherwise (including if there is no MSI irq domain) + */ +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 (irq_domain_is_msi(h) && + !irq_domain_hierarchical_is_msi_remap(h)) { + ret = false; + break; + } + } + 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