[RFC v4 14/16] vfio/type1: Allow transparent MSI IOVA allocation

[Eric Auger]

When attaching a group to the container, check the group's
reserved regions and test whether the IOMMU translates MSI
transactions. If yes, we initialize an IOVA allocator through
the iommu_get_msi_cookie API. This will allow the MSI IOVAs
to be transparently allocated on MSI controller's compose().

Signed-off-by: Eric Auger <eric.au...@redhat.com>

---

v3 -> v4:
- test region's type: IOMMU_RESV_MSI
- restructure the code to prepare for safety assessment
- reword title
---
 drivers/vfio/vfio_iommu_type1.c | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 2ba1942..d07fe73 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -36,6 +36,7 @@
 #include <linux/uaccess.h>
 #include <linux/vfio.h>
 #include <linux/workqueue.h>
+#include <linux/dma-iommu.h>
 
 #define DRIVER_VERSION  "0.2"
 #define DRIVER_AUTHOR   "Alex Williamson <alex.william...@redhat.com>"
@@ -734,6 +735,28 @@ static void vfio_test_domain_fgsp(struct vfio_domain 
*domain)
        __free_pages(pages, order);
 }
 
+static bool vfio_iommu_has_resv_msi(struct iommu_group *group,
+                                   phys_addr_t *base)
+{
+       struct list_head group_resv_regions;
+       struct iommu_resv_region *region, *next;
+       bool ret = false;
+
+       INIT_LIST_HEAD(&group_resv_regions);
+       iommu_get_group_resv_regions(group, &group_resv_regions);
+       list_for_each_entry(region, &group_resv_regions, list) {
+               if (region->type & IOMMU_RESV_MSI) {
+                       *base = region->start;
+                       ret = true;
+                       goto out;
+               }
+       }
+out:
+       list_for_each_entry_safe(region, next, &group_resv_regions, list)
+               kfree(region);
+       return ret;
+}
+
 static int vfio_iommu_type1_attach_group(void *iommu_data,
                                         struct iommu_group *iommu_group)
 {
@@ -742,6 +765,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
        struct vfio_domain *domain, *d;
        struct bus_type *bus = NULL;
        int ret;
+       bool resv_msi;
+       phys_addr_t resv_msi_base;
 
        mutex_lock(&iommu->lock);
 
@@ -788,6 +813,8 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
        if (ret)
                goto out_domain;
 
+       resv_msi = vfio_iommu_has_resv_msi(iommu_group, &resv_msi_base);
+
        INIT_LIST_HEAD(&domain->group_list);
        list_add(&group->next, &domain->group_list);
 
@@ -834,6 +861,9 @@ static int vfio_iommu_type1_attach_group(void *iommu_data,
        if (ret)
                goto out_detach;
 
+       if (resv_msi && iommu_get_msi_cookie(domain->domain, resv_msi_base))
+               goto out_detach;
+
        list_add(&domain->next, &iommu->domain_list);
 
        mutex_unlock(&iommu->lock);
-- 
1.9.1

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