On x86 IRQ remapping is abstracted by the IOMMU. On ARM this is abstracted
by the msi controller. vfio_safe_irq_domain allows to check whether
interrupts are "safe" for a given device. They 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,
we 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 <eric.auger@xxxxxxxxxx>
---
v3 -> v4:
- rename vfio_msi_parent_irq_remapping_capable into vfio_safe_irq_domain
and irq_remapping into safe_irq_domains
v2 -> v3:
- protect vfio_msi_parent_irq_remapping_capable with
CONFIG_GENERIC_MSI_IRQ_DOMAIN
---
drivers/vfio/vfio_iommu_type1.c | 44 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 42 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 4497b20..b330b81 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -37,6 +37,8 @@
#include <linux/vfio.h>
#include <linux/workqueue.h>
#include <linux/dma-reserved-iommu.h>
+#include <linux/irqdomain.h>
+#include <linux/msi.h>
#define DRIVER_VERSION "0.2"
#define DRIVER_AUTHOR "Alex Williamson <alex.williamson@xxxxxxxxxx>"
@@ -788,6 +790,33 @@ static int vfio_bus_type(struct device *dev, void *data)
return 0;
}
+/**
+ * vfio_safe_irq_domain: returns whether the irq domain
+ * the device is attached to is safe with respect to MSI isolation.
+ * If the irq domain is not an MSI domain, we return it is safe.
+ *
+ * @dev: device handle
+ * @data: unused
+ * returns 0 if the irq domain is safe, -1 if not.
+ */
+static int vfio_safe_irq_domain(struct device *dev, void *data)
+{
+#ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
+ 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;
+#endif
+ return 0;
+}
+
static int vfio_iommu_replay(struct vfio_iommu *iommu,
struct vfio_domain *domain)
{
@@ -882,7 +911,7 @@ 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, safe_irq_domains;
mutex_lock(&iommu->lock);
@@ -905,6 +934,13 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
group->iommu_group = iommu_group;
+ /*
+ * Determine if all the devices of the group have a safe irq domain
+ * with respect to MSI isolation
+ */
+ safe_irq_domains = !iommu_group_for_each_dev(iommu_group, &bus,
+ vfio_safe_irq_domain);
+
/* Determine bus_type in order to allocate a domain */
ret = iommu_group_for_each_dev(iommu_group, &bus, vfio_bus_type);
if (ret)
@@ -932,8 +968,12 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
INIT_LIST_HEAD(&domain->group_list);
list_add(&group->next, &domain->group_list);
+ /*
+ * to advertise safe interrupts either the IOMMU or the MSI controllers
+ * must support IRQ remapping/interrupt translation
+ */
if (!allow_unsafe_interrupts &&
- !iommu_capable(bus, IOMMU_CAP_INTR_REMAP)) {
+ (!iommu_capable(bus, IOMMU_CAP_INTR_REMAP) && !safe_irq_domains)) {
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
--
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