On x86 IRQ remapping is abstracted by the IOMMU. On ARM this is abstracted by the msi controller. vfio_msi_parent_irq_remapping_capable allows to check whether interrupts are "safe" for a given device. There are if the device does not use MSI or if the device uses MSI and the msi-parent controller supports IRQ remapping.
Then we check at group level if all devices have safe interrupts: if not only allow the group to be attached if allow_unsafe_interrupts is set. At this point ARM sMMU still advertises IOMMU_CAP_INTR_REMAP. This is changed in next patch. Signed-off-by: Eric Auger <[email protected]> --- drivers/vfio/vfio_iommu_type1.c | 38 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 36 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c index c5d3b48..080321b 100644 --- a/drivers/vfio/vfio_iommu_type1.c +++ b/drivers/vfio/vfio_iommu_type1.c @@ -36,6 +36,8 @@ #include <linux/uaccess.h> #include <linux/vfio.h> #include <linux/workqueue.h> +#include <linux/irqdomain.h> +#include <linux/msi.h> #define DRIVER_VERSION "0.2" #define DRIVER_AUTHOR "Alex Williamson <[email protected]>" @@ -754,6 +756,31 @@ static int vfio_bus_type(struct device *dev, void *data) return 0; } +/** + * vfio_msi_parent_irq_remapping_capable: returns whether the device msi-parent + * controller supports IRQ remapping, aka interrupt translation + * + * @dev: device handle + * @data: unused + * returns 0 if irq remapping is supported or -1 if not supported. + */ +static int vfio_msi_parent_irq_remapping_capable(struct device *dev, void *data) +{ + struct irq_domain *domain; + struct msi_domain_info *info; + + domain = dev_get_msi_domain(dev); + if (!domain) + return 0; + + info = msi_get_domain_info(domain); + + if (!(info->flags & MSI_FLAG_IRQ_REMAPPING)) + return -1; + + return 0; +} + static int vfio_iommu_replay(struct vfio_iommu *iommu, struct vfio_domain *domain) { @@ -848,7 +875,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, struct vfio_group *group, *g; struct vfio_domain *domain, *d; struct bus_type *bus = NULL; - int ret; + int ret, irq_remapping; mutex_lock(&iommu->lock); @@ -871,6 +898,13 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, group->iommu_group = iommu_group; + /* + * Determine if all the devices of the group has an MSI-parent that + * supports irq remapping + */ + irq_remapping = !iommu_group_for_each_dev(iommu_group, &bus, + vfio_msi_parent_irq_remapping_capable); + /* Determine bus_type in order to allocate a domain */ ret = iommu_group_for_each_dev(iommu_group, &bus, vfio_bus_type); if (ret) @@ -899,7 +933,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, list_add(&group->next, &domain->group_list); if (!allow_unsafe_interrupts && - !iommu_capable(bus, IOMMU_CAP_INTR_REMAP)) { + (!iommu_capable(bus, IOMMU_CAP_INTR_REMAP) && !irq_remapping)) { pr_warn("%s: No interrupt remapping support. Use the module param \"allow_unsafe_interrupts\" to enable VFIO IOMMU support on this platform\n", __func__); ret = -EPERM; -- 1.9.1
