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>

2 files changed, 51 insertions, 57 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);
     }
 }
diff --git a/hw/pci/pcie_sriov.c b/hw/pci/pcie_sriov.c
index 91c64c9..f1993bc 100644
--- a/hw/pci/pcie_sriov.c
+++ b/hw/pci/pcie_sriov.c
@@ -20,9 +20,16 @@
 #include "qapi/error.h"
 #include "trace.h"
 
-static PCIDevice *register_vf(PCIDevice *pf, int devfn,
-                              const char *name, uint16_t vf_num);
-static void unregister_vfs(PCIDevice *dev);
+static void unparent_vfs(PCIDevice *dev, uint16_t total_vfs)
+{
+    for (uint16_t i = 0; i < total_vfs; i++) {
+        PCIDevice *vf = dev->exp.sriov_pf.vf[i];
+        object_unparent(OBJECT(vf));
+        object_unref(OBJECT(vf));
+    }
+    g_free(dev->exp.sriov_pf.vf);
+    dev->exp.sriov_pf.vf = NULL;
+}
 
 bool pcie_sriov_pf_init(PCIDevice *dev, uint16_t offset,
                         const char *vfname, uint16_t vf_dev_id,
@@ -30,6 +37,7 @@ bool pcie_sriov_pf_init(PCIDevice *dev, uint16_t offset,
                         uint16_t vf_offset, uint16_t vf_stride,
                         Error **errp)
 {
+    BusState *bus = qdev_get_parent_bus(&dev->qdev);
     int32_t devfn = dev->devfn + vf_offset;
     uint8_t *cfg = dev->config + offset;
     uint8_t *wmask;
@@ -44,7 +52,6 @@ bool pcie_sriov_pf_init(PCIDevice *dev, uint16_t offset,
                         offset, PCI_EXT_CAP_SRIOV_SIZEOF);
     dev->exp.sriov_cap = offset;
     dev->exp.sriov_pf.num_vfs = 0;
-    dev->exp.sriov_pf.vfname = g_strdup(vfname);
     dev->exp.sriov_pf.vf = NULL;
 
     pci_set_word(cfg + PCI_SRIOV_VF_OFFSET, vf_offset);
@@ -78,14 +85,34 @@ bool pcie_sriov_pf_init(PCIDevice *dev, uint16_t offset,
 
     qdev_prop_set_bit(&dev->qdev, "multifunction", true);
 
+    dev->exp.sriov_pf.vf = g_new(PCIDevice *, total_vfs);
+
+    for (uint16_t i = 0; i < total_vfs; i++) {
+        PCIDevice *vf = pci_new(devfn, vfname);
+        vf->exp.sriov_vf.pf = dev;
+        vf->exp.sriov_vf.vf_number = i;
+
+        if (!qdev_realize(&vf->qdev, bus, errp)) {
+            unparent_vfs(dev, i);
+            return false;
+        }
+
+        /* set vid/did according to sr/iov spec - they are not used */
+        pci_config_set_vendor_id(vf->config, 0xffff);
+        pci_config_set_device_id(vf->config, 0xffff);
+
+        dev->exp.sriov_pf.vf[i] = vf;
+        devfn += vf_stride;
+    }
+
     return true;
 }
 
 void pcie_sriov_pf_exit(PCIDevice *dev)
 {
-    unregister_vfs(dev);
-    g_free((char *)dev->exp.sriov_pf.vfname);
-    dev->exp.sriov_pf.vfname = NULL;
+    uint8_t *cfg = dev->config + dev->exp.sriov_cap;
+
+    unparent_vfs(dev, pci_get_word(cfg + PCI_SRIOV_TOTAL_VF));
 }
 
 void pcie_sriov_pf_init_vf_bar(PCIDevice *dev, int region_num,
@@ -151,38 +178,11 @@ void pcie_sriov_vf_register_bar(PCIDevice *dev, int region_num,
     }
 }
 
-static PCIDevice *register_vf(PCIDevice *pf, int devfn, const char *name,
-                              uint16_t vf_num)
-{
-    PCIDevice *dev = pci_new(devfn, name);
-    dev->exp.sriov_vf.pf = pf;
-    dev->exp.sriov_vf.vf_number = vf_num;
-    PCIBus *bus = pci_get_bus(pf);
-    Error *local_err = NULL;
-
-    qdev_realize(&dev->qdev, &bus->qbus, &local_err);
-    if (local_err) {
-        error_report_err(local_err);
-        return NULL;
-    }
-
-    /* set vid/did according to sr/iov spec - they are not used */
-    pci_config_set_vendor_id(dev->config, 0xffff);
-    pci_config_set_device_id(dev->config, 0xffff);
-
-    return dev;
-}
-
 static void register_vfs(PCIDevice *dev)
 {
     uint16_t num_vfs;
     uint16_t i;
     uint16_t sriov_cap = dev->exp.sriov_cap;
-    uint16_t vf_offset =
-        pci_get_word(dev->config + sriov_cap + PCI_SRIOV_VF_OFFSET);
-    uint16_t vf_stride =
-        pci_get_word(dev->config + sriov_cap + PCI_SRIOV_VF_STRIDE);
-    int32_t devfn = dev->devfn + vf_offset;
 
     assert(sriov_cap > 0);
     num_vfs = pci_get_word(dev->config + sriov_cap + PCI_SRIOV_NUM_VF);
@@ -190,18 +190,10 @@ static void register_vfs(PCIDevice *dev)
         return;
     }
 
-    dev->exp.sriov_pf.vf = g_new(PCIDevice *, num_vfs);
-
     trace_sriov_register_vfs(dev->name, PCI_SLOT(dev->devfn),
                              PCI_FUNC(dev->devfn), num_vfs);
     for (i = 0; i < num_vfs; i++) {
-        dev->exp.sriov_pf.vf[i] = register_vf(dev, devfn,
-                                              dev->exp.sriov_pf.vfname, i);
-        if (!dev->exp.sriov_pf.vf[i]) {
-            num_vfs = i;
-            break;
-        }
-        devfn += vf_stride;
+        pci_set_enabled(dev->exp.sriov_pf.vf[i], true);
     }
     dev->exp.sriov_pf.num_vfs = num_vfs;
 }
@@ -214,12 +206,8 @@ static void unregister_vfs(PCIDevice *dev)
     trace_sriov_unregister_vfs(dev->name, PCI_SLOT(dev->devfn),
                                PCI_FUNC(dev->devfn), num_vfs);
     for (i = 0; i < num_vfs; i++) {
-        PCIDevice *vf = dev->exp.sriov_pf.vf[i];
-        object_unparent(OBJECT(vf));
-        object_unref(OBJECT(vf));
+        pci_set_enabled(dev->exp.sriov_pf.vf[i], false);
     }
-    g_free(dev->exp.sriov_pf.vf);
-    dev->exp.sriov_pf.vf = NULL;
     dev->exp.sriov_pf.num_vfs = 0;
 }
 
@@ -241,14 +229,10 @@ void pcie_sriov_config_write(PCIDevice *dev, uint32_t address,
                              PCI_FUNC(dev->devfn), off, val, len);
 
     if (range_covers_byte(off, len, PCI_SRIOV_CTRL)) {
-        if (dev->exp.sriov_pf.num_vfs) {
-            if (!(val & PCI_SRIOV_CTRL_VFE)) {
-                unregister_vfs(dev);
-            }
+        if (val & PCI_SRIOV_CTRL_VFE) {
+            register_vfs(dev);
         } else {
-            if (val & PCI_SRIOV_CTRL_VFE) {
-                register_vfs(dev);
-            }
+            unregister_vfs(dev);
         }
     }
 }