pcie_sriov: Reuse SR-IOV VF device instances

Disable SR-IOV VF devices by reusing code to power down PCI devices
instead of removing them when the guest requests to disable VFs. This
allows to realize devices and report VF realization errors at PF
realization time.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250116-reuse-v20-8-7cb370606368@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 2afa423..3e29b30 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -2963,7 +2963,17 @@ MSIMessage pci_get_msi_message(PCIDevice *dev, int vector)
 
 void pci_set_power(PCIDevice *d, bool state)
 {
-    pci_set_enabled(d, state);
+    /*
+     * Don't change the enabled state of VFs when powering on/off the device.
+     *
+     * When powering on, VFs must not be enabled immediately but they must
+     * wait until the guest configures SR-IOV.
+     * When powering off, their corresponding PFs will be reset and disable
+     * VFs.
+     */
+    if (!pci_is_vf(d)) {
+        pci_set_enabled(d, state);
+    }
 }
 
 void pci_set_enabled(PCIDevice *d, bool state)
@@ -2977,7 +2987,7 @@ void pci_set_enabled(PCIDevice *d, bool state)
     memory_region_set_enabled(&d->bus_master_enable_region,
                               (pci_get_word(d->config + PCI_COMMAND)
                                & PCI_COMMAND_MASTER) && d->enabled);
-    if (!d->enabled) {
+    if (qdev_is_realized(&d->qdev)) {
         pci_device_reset(d);
     }
 }