The code generating errors in pci_add_capability has a comment which
says:
> Verify that capabilities don't overlap.  Note: device assignment
> depends on this check to verify that the device is not broken.
> Should never trigger for emulated devices, but it's helpful for
> debugging these.

Indeed vfio has some code that passes capability offsets and sizes from
a physical device, but it explicitly pays attention so that the
capabilities never overlap. Therefore, in pci_add_capability(), we can
always assert that capabilities never overlap, and that is what happens
when omitting errp.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 hw/vfio/pci-quirks.c | 15 +++------------
 hw/vfio/pci.c        | 14 +++++---------
 2 files changed, 8 insertions(+), 21 deletions(-)

diff --git a/hw/vfio/pci-quirks.c b/hw/vfio/pci-quirks.c
index f0147a050a..e94fd273ea 100644
--- a/hw/vfio/pci-quirks.c
+++ b/hw/vfio/pci-quirks.c
@@ -1530,7 +1530,7 @@ const PropertyInfo qdev_prop_nv_gpudirect_clique = {
 static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
 {
     PCIDevice *pdev = &vdev->pdev;
-    int ret, pos = 0xC8;
+    int pos = 0xC8;
 
     if (vdev->nv_gpudirect_clique == 0xFF) {
         return 0;
@@ -1547,11 +1547,7 @@ static int vfio_add_nv_gpudirect_cap(VFIOPCIDevice *vdev, Error **errp)
         return -EINVAL;
     }
 
-    ret = pci_add_capability(pdev, PCI_CAP_ID_VNDR, pos, 8, errp);
-    if (ret < 0) {
-        error_prepend(errp, "Failed to add NVIDIA GPUDirect cap: ");
-        return ret;
-    }
+    pci_add_capability(pdev, PCI_CAP_ID_VNDR, pos, 8);
 
     memset(vdev->emulated_config_bits + pos, 0xFF, 8);
     pos += PCI_CAP_FLAGS;
@@ -1718,12 +1714,7 @@ static int vfio_add_vmd_shadow_cap(VFIOPCIDevice *vdev, Error **errp)
         return -EFAULT;
     }
 
-    ret = pci_add_capability(&vdev->pdev, PCI_CAP_ID_VNDR, pos,
-                             VMD_SHADOW_CAP_LEN, errp);
-    if (ret < 0) {
-        error_prepend(errp, "Failed to add VMD MEMBAR Shadow cap: ");
-        return ret;
-    }
+    pci_add_capability(&vdev->pdev, PCI_CAP_ID_VNDR, pos, VMD_SHADOW_CAP_LEN);
 
     memset(vdev->emulated_config_bits + pos, 0xFF, VMD_SHADOW_CAP_LEN);
     pos += PCI_CAP_FLAGS;
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 0ca6b5ff4b..458729eae3 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -1839,7 +1839,7 @@ static void vfio_add_emulated_long(VFIOPCIDevice *vdev, int pos,
     vfio_set_long_bits(vdev->emulated_config_bits + pos, mask, mask);
 }
 
-static int vfio_setup_pcie_cap(VFIOPCIDevice *vdev, int pos, uint8_t size,
+static int vfio_setup_pcie_cap(VFIOPCIDevice *vdev, uint8_t pos, uint8_t size,
                                Error **errp)
 {
     uint16_t flags;
@@ -1956,11 +1956,7 @@ static int vfio_setup_pcie_cap(VFIOPCIDevice *vdev, int pos, uint8_t size,
                                1, PCI_EXP_FLAGS_VERS);
     }
 
-    pos = pci_add_capability(&vdev->pdev, PCI_CAP_ID_EXP, pos, size,
-                             errp);
-    if (pos < 0) {
-        return pos;
-    }
+    pos = pci_add_capability(&vdev->pdev, PCI_CAP_ID_EXP, pos, size);
 
     vdev->pdev.exp.exp_cap = pos;
 
@@ -2058,14 +2054,14 @@ static int vfio_add_std_cap(VFIOPCIDevice *vdev, uint8_t pos, Error **errp)
     case PCI_CAP_ID_PM:
         vfio_check_pm_reset(vdev, pos);
         vdev->pm_cap = pos;
-        ret = pci_add_capability(pdev, cap_id, pos, size, errp);
+        pci_add_capability(pdev, cap_id, pos, size);
         break;
     case PCI_CAP_ID_AF:
         vfio_check_af_flr(vdev, pos);
-        ret = pci_add_capability(pdev, cap_id, pos, size, errp);
+        pci_add_capability(pdev, cap_id, pos, size);
         break;
     default:
-        ret = pci_add_capability(pdev, cap_id, pos, size, errp);
+        pci_add_capability(pdev, cap_id, pos, size);
         break;
     }
 
-- 
2.38.1