This patch allows the user-space to retrieve whether msi write
transaction addresses must be mapped. This is returned through the
VFIO_IOMMU_GET_INFO API and its new flag: VFIO_IOMMU_INFO_REQUIRE_MSI_MAP.

Signed-off-by: Bharat Bhushan <bharat.bhus...@freescale.com>
Signed-off-by: Eric Auger <eric.au...@linaro.org>

---

RFC v1 -> v1:
- derived from
  [RFC PATCH 3/6] vfio: Extend iommu-info to return MSIs automap state
- renamed allow_msi_reconfig into require_msi_mapping
- fixed VFIO_IOMMU_GET_INFO
---
 drivers/vfio/vfio_iommu_type1.c | 26 ++++++++++++++++++++++++++
 include/uapi/linux/vfio.h       |  1 +
 2 files changed, 27 insertions(+)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 6f1ea3d..c5b57e1 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -255,6 +255,29 @@ static int vaddr_get_pfn(unsigned long vaddr, int prot, 
unsigned long *pfn)
 }
 
 /*
+ * vfio_domains_require_msi_mapping: indicates whether MSI write transaction
+ * addresses must be mapped
+ *
+ * returns true if it does
+ */
+static bool vfio_domains_require_msi_mapping(struct vfio_iommu *iommu)
+{
+       struct vfio_domain *d;
+       bool ret;
+
+       mutex_lock(&iommu->lock);
+       /* All domains have same require_msi_map property, pick first */
+       d = list_first_entry(&iommu->domain_list, struct vfio_domain, next);
+       if (iommu_domain_get_attr(d->domain, DOMAIN_ATTR_MSI_MAPPING, NULL) < 0)
+               ret = false;
+       else
+               ret = true;
+       mutex_unlock(&iommu->lock);
+
+       return ret;
+}
+
+/*
  * Attempt to pin pages.  We really don't want to track all the pfns and
  * the iommu can only map chunks of consecutive pfns anyway, so get the
  * first page and all consecutive pages with the same locking.
@@ -997,6 +1020,9 @@ static long vfio_iommu_type1_ioctl(void *iommu_data,
 
                info.flags = VFIO_IOMMU_INFO_PGSIZES;
 
+               if (vfio_domains_require_msi_mapping(iommu))
+                       info.flags |= VFIO_IOMMU_INFO_REQUIRE_MSI_MAP;
+
                info.iova_pgsizes = vfio_pgsize_bitmap(iommu);
 
                return copy_to_user((void __user *)arg, &info, minsz);
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 7d7a4c6..43e183b 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -400,6 +400,7 @@ struct vfio_iommu_type1_info {
        __u32   argsz;
        __u32   flags;
 #define VFIO_IOMMU_INFO_PGSIZES (1 << 0)       /* supported page sizes info */
+#define VFIO_IOMMU_INFO_REQUIRE_MSI_MAP (1 << 1)/* MSI must be mapped */
        __u64   iova_pgsizes;           /* Bitmap of supported page sizes */
 };
 
-- 
1.9.1

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