[Qemu-devel] [PATCH v7 2/4] vfio: Add vfio_container_spapr_get_info()

[Alexey Kardashevskiy <aik@ozlabs.ru>]

To perform DMA mapping via TCE table correctly, the guest must
know where DMA window is located on the PCI bus. A hypervisor is
expected to provide such information. Since QEMU has no control
over this setting, we need a way to obtain a start address and size
from the host VFIO driver.

This adds a helper which returns the default DMA window properties
for the specific IOMMU group. The upstream kernel implements this ioctl
already.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
Changes:
v7:
* do not return a group fd from the helper

v6:
* added dup() to protect group_fd from accidental disposal

v5:
* reworked to reflect change in vfio_get_group() from one
of previous patches change

v4:
* fixed possible leaks on error paths
---
 hw/misc/vfio.c         | 36 ++++++++++++++++++++++++++++++++++++
 include/hw/misc/vfio.h | 11 +++++++++++
 2 files changed, 47 insertions(+)
 create mode 100644 include/hw/misc/vfio.h

diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
index 7437c2e..99141f3 100644
--- a/hw/misc/vfio.c
+++ b/hw/misc/vfio.c
@@ -39,6 +39,7 @@
 #include "qemu/range.h"
 #include "sysemu/kvm.h"
 #include "sysemu/sysemu.h"
+#include "hw/misc/vfio.h"
 
 /* #define DEBUG_VFIO */
 #ifdef DEBUG_VFIO
@@ -4318,3 +4319,38 @@ static void register_vfio_pci_dev_type(void)
 }
 
 type_init(register_vfio_pci_dev_type)
+
+int vfio_container_spapr_get_info(AddressSpace *as,
+                                  int32_t groupid,
+                                  struct vfio_iommu_spapr_tce_info *info)
+{
+    VFIOGroup *group;
+    VFIOContainer *container;
+    int ret, fd;
+
+    group = vfio_get_group(groupid, as);
+    if (!group) {
+        return -1;
+    }
+    container = group->container;
+    if (!group->container) {
+        goto put_group_exit;
+    }
+    fd = container->fd;
+    if (!ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU)) {
+        goto put_group_exit;
+    }
+    ret = ioctl(fd, VFIO_IOMMU_SPAPR_TCE_GET_INFO, info);
+    if (ret) {
+        error_report("vfio: failed to get iommu info for container: %s",
+                     strerror(errno));
+        goto put_group_exit;
+    }
+
+    return 0;
+
+put_group_exit:
+    vfio_put_group(group);
+
+    return -1;
+}
diff --git a/include/hw/misc/vfio.h b/include/hw/misc/vfio.h
new file mode 100644
index 0000000..e82f5a3
--- /dev/null
+++ b/include/hw/misc/vfio.h
@@ -0,0 +1,11 @@
+#ifndef VFIO_API_H
+#define VFIO_API_H
+
+#include "qemu/typedefs.h"
+#include <linux/vfio.h>
+
+extern int vfio_container_spapr_get_info(AddressSpace *as,
+                                         int32_t groupid,
+                                         struct vfio_iommu_spapr_tce_info *info);
+
+#endif
-- 
2.0.0