vfio: Implement a common device info helper

A common helper implementing the realloc algorithm for handling
capabilities.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Robin Voetter <robin@streamhpc.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 5 insertions, 32 deletions

diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
index f51190d..59a2e03 100644
--- a/hw/s390x/s390-pci-vfio.c
+++ b/hw/s390x/s390-pci-vfio.c
@@ -289,38 +289,11 @@ static void s390_pci_read_pfip(S390PCIBusDevice *pbdev,
     memcpy(pbdev->zpci_fn.pfip, cap->pfip, CLP_PFIP_NR_SEGMENTS);
 }
 
-static struct vfio_device_info *get_device_info(S390PCIBusDevice *pbdev,
-                                                uint32_t argsz)
+static struct vfio_device_info *get_device_info(S390PCIBusDevice *pbdev)
 {
-    struct vfio_device_info *info = g_malloc0(argsz);
-    VFIOPCIDevice *vfio_pci;
-    int fd;
+    VFIOPCIDevice *vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
 
-    vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
-    fd = vfio_pci->vbasedev.fd;
-
-    /*
-     * If the specified argsz is not large enough to contain all capabilities
-     * it will be updated upon return from the ioctl.  Retry until we have
-     * a big enough buffer to hold the entire capability chain.  On error,
-     * just exit and rely on CLP defaults.
-     */
-retry:
-    info->argsz = argsz;
-
-    if (ioctl(fd, VFIO_DEVICE_GET_INFO, info)) {
-        trace_s390_pci_clp_dev_info(vfio_pci->vbasedev.name);
-        g_free(info);
-        return NULL;
-    }
-
-    if (info->argsz > argsz) {
-        argsz = info->argsz;
-        info = g_realloc(info, argsz);
-        goto retry;
-    }
-
-    return info;
+    return vfio_get_device_info(vfio_pci->vbasedev.fd);
 }
 
 /*
@@ -335,7 +308,7 @@ bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh)
 
     assert(fh);
 
-    info = get_device_info(pbdev, sizeof(*info));
+    info = get_device_info(pbdev);
     if (!info) {
         return false;
     }
@@ -356,7 +329,7 @@ void s390_pci_get_clp_info(S390PCIBusDevice *pbdev)
 {
     g_autofree struct vfio_device_info *info = NULL;
 
-    info = get_device_info(pbdev, sizeof(*info));
+    info = get_device_info(pbdev);
     if (!info) {
         return;
     }