[PATCH 08/19] pci-assign: Factor out kvm_device_msix_supported

[Jan Kiszka <jan.kiszka@xxxxxxxxxxx>]

Encapsulate the ugly check if MSI-X assignment is supported in a
separate helper function.

Signed-off-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
---
 hw/device-assignment.c |    5 +----
 target-i386/kvm.c      |    7 +++++++
 target-i386/kvm_i386.h |    1 +
 3 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/hw/device-assignment.c b/hw/device-assignment.c
index 1d0af34..80ac2fc 100644
--- a/hw/device-assignment.c
+++ b/hw/device-assignment.c
@@ -1283,10 +1283,7 @@ static int assigned_device_pci_cap_init(PCIDevice *pci_dev)
     }
     /* Expose MSI-X capability */
     pos = pci_find_cap_offset(pci_dev, PCI_CAP_ID_MSIX, 0);
-    /* Would really like to test kvm_check_extension(, KVM_CAP_DEVICE_MSIX),
-     * but the kernel doesn't expose it.  Instead do a dummy call to
-     * KVM_ASSIGN_SET_MSIX_NR to see if it exists. */
-    if (pos != 0 && kvm_assign_set_msix_nr(kvm_state, NULL) == -EFAULT) {
+    if (pos != 0 && kvm_device_msix_supported(kvm_state)) {
         int bar_nr;
         uint32_t msix_table_entry;
 
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index 04d1c7d..677a791 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -2154,6 +2154,13 @@ int kvm_device_msi_deassign(KVMState *s, uint32_t dev_id)
                                                 KVM_DEV_IRQ_HOST_MSI);
 }
 
+bool kvm_device_msix_supported(KVMState *s)
+{
+    /* The kernel lacks a corresponding KVM_CAP, so we probe by calling
+     * KVM_ASSIGN_SET_MSIX_NR with an invalid parameter. */
+    return kvm_vm_ioctl(s, KVM_ASSIGN_SET_MSIX_NR, NULL) == -EFAULT;
+}
+
 int kvm_device_msix_deassign(KVMState *s, uint32_t dev_id)
 {
     return kvm_deassign_irq_internal(s, dev_id, KVM_DEV_IRQ_GUEST_MSIX |
diff --git a/target-i386/kvm_i386.h b/target-i386/kvm_i386.h
index e827f5b..6f66b6d 100644
--- a/target-i386/kvm_i386.h
+++ b/target-i386/kvm_i386.h
@@ -27,6 +27,7 @@ int kvm_device_intx_deassign(KVMState *s, uint32_t dev_id, bool use_host_msi);
 int kvm_device_msi_assign(KVMState *s, uint32_t dev_id, int virq);
 int kvm_device_msi_deassign(KVMState *s, uint32_t dev_id);
 
+bool kvm_device_msix_supported(KVMState *s);
 int kvm_device_msix_deassign(KVMState *s, uint32_t dev_id);
 
 #endif
-- 
1.7.3.4

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