iommu: Add iommu_group_has_isolated_msi()

Compute the isolated_msi over all the devices in the IOMMU group because
iommufd and vfio both need to know that the entire group is isolated
before granting access to it.

Link: https://lore.kernel.org/r/[email protected]
Tested-by: Matthew Rosato <[email protected]>
Reviewed-by: Kevin Tian <[email protected]>
Reviewed-by: Lu Baolu <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

2 files changed, 27 insertions, 0 deletions

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index de91dd88705b..4c2199a493d8 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -30,6 +30,7 @@
 #include <linux/cc_platform.h>
 #include <trace/events/iommu.h>
 #include <linux/sched/mm.h>
+#include <linux/msi.h>
 
 #include "dma-iommu.h"
 
@@ -1898,6 +1899,31 @@ bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 EXPORT_SYMBOL_GPL(device_iommu_capable);
 
 /**
+ * iommu_group_has_isolated_msi() - Compute msi_device_has_isolated_msi()
+ *       for a group
+ * @group: Group to query
+ *
+ * IOMMU groups should not have differing values of
+ * msi_device_has_isolated_msi() for devices in a group. However nothing
+ * directly prevents this, so ensure mistakes don't result in isolation failures
+ * by checking that all the devices are the same.
+ */
+bool iommu_group_has_isolated_msi(struct iommu_group *group)
+{
+	struct group_device *group_dev;
+	bool ret = true;
+
+	mutex_lock(&group->mutex);
+	list_for_each_entry(group_dev, &group->devices, list) {
+		ret &= msi_device_has_isolated_msi(group_dev->dev) ||
+		       device_iommu_capable(group_dev->dev, IOMMU_CAP_INTR_REMAP);
+	}
+	mutex_unlock(&group->mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_has_isolated_msi);
+
+/**
  * iommu_set_fault_handler() - set a fault handler for an iommu domain
  * @domain: iommu domain
  * @handler: fault handler
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 46e1347bfa22..9b7a9fa5ad28 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -455,6 +455,7 @@ static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
 extern int bus_iommu_probe(struct bus_type *bus);
 extern bool iommu_present(struct bus_type *bus);
 extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
+extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
 extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
 extern struct iommu_group *iommu_group_get_by_id(int id);
 extern void iommu_domain_free(struct iommu_domain *domain);