[PATCH] pci-assign: Do not expose MSI/MSI-X if the kernel does not support it

[Jan Kiszka <jan.kiszka@siemens.com>]

Add checks for KVM_CAP_ASSIGN_DEV_IRQ (MSI) and KVM_CAP_DEVICE_MSIX, do
not set up MSI/MSI-X if the required kernel features are missing.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 hw/device-assignment.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/hw/device-assignment.c b/hw/device-assignment.c
index 4cc7b1a..7e965cb 100644
--- a/hw/device-assignment.c
+++ b/hw/device-assignment.c
@@ -1201,7 +1201,8 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
 
     /* Expose MSI capability
      * MSI capability is the 1st capability in capability config */
-    if ((pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_MSI, 0))) {
+    pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_MSI, 0);
+    if (pos != 0 && kvm_check_extension(kvm_state, KVM_CAP_ASSIGN_DEV_IRQ)) {
         dev->cap.available |= ASSIGNED_DEVICE_CAP_MSI;
         /* Only 32-bit/no-mask currently supported */
         if ((ret = pci_add_capability(pci_dev, PCI_CAP_ID_MSI, pos, 10)) < 0) {
@@ -1222,7 +1223,8 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
         pci_set_word(pci_dev->wmask + pos + PCI_MSI_DATA_32, 0xffff);
     }
     /* Expose MSI-X capability */
-    if ((pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_MSIX, 0))) {
+    pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_MSIX, 0);
+    if (pos != 0 && kvm_check_extension(kvm_state, KVM_CAP_DEVICE_MSIX)) {
         int bar_nr;
         uint32_t msix_table_entry;
 
-- 
1.7.3.4