[PATCH v5 3/3] s390x/pci: Reset a device in error state

[Farhan Ali <alifm@linux.ibm.com>]

For passthrough devices in error state, for a guest driven reset of the
device we can attempt a reset to recover the device. A reset of the device
will trigger a CLP disable/enable cycle on the host to bring the device
into a recovered state.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
---
 hw/s390x/s390-pci-bus.c          | 7 +++++++
 hw/s390x/s390-pci-vfio-stubs.c   | 4 ++++
 hw/s390x/s390-pci-vfio.c         | 9 +++++++++
 include/hw/s390x/s390-pci-vfio.h | 1 +
 4 files changed, 21 insertions(+)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index b2967dacba..8418da9372 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -1505,6 +1505,8 @@ static void s390_pci_device_reset(DeviceState *dev)
         return;
     case ZPCI_FS_STANDBY:
         break;
+    case ZPCI_FS_ERROR:
+        break;
     default:
         pbdev->fh &= ~FH_MASK_ENABLE;
         pbdev->state = ZPCI_FS_DISABLED;
@@ -1517,6 +1519,11 @@ static void s390_pci_device_reset(DeviceState *dev)
     } else if (pbdev->summary_ind) {
         pci_dereg_irqs(pbdev);
     }
+
+    if (pbdev->state == ZPCI_FS_ERROR) {
+        s390_pci_reset(pbdev);
+    }
+
     if (pbdev->iommu->enabled) {
         pci_dereg_ioat(pbdev->iommu);
     }
diff --git a/hw/s390x/s390-pci-vfio-stubs.c b/hw/s390x/s390-pci-vfio-stubs.c
index 9fc84ca135..c68c612038 100644
--- a/hw/s390x/s390-pci-vfio-stubs.c
+++ b/hw/s390x/s390-pci-vfio-stubs.c
@@ -36,3 +36,7 @@ bool s390_pci_setup_err_handler(S390PCIBusDevice *pbdev, Error **errp)
     error_setg(errp, "VFIO not available, cannot setup error handler");
     return false;
 }
+
+void s390_pci_reset(S390PCIBusDevice *pbdev)
+{
+}
diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
index 6c072005fd..37d2f49658 100644
--- a/hw/s390x/s390-pci-vfio.c
+++ b/hw/s390x/s390-pci-vfio.c
@@ -185,6 +185,15 @@ static void s390_pci_err_handler(void *opaque)
     return;
 }
 
+void s390_pci_reset(S390PCIBusDevice *pbdev)
+{
+    VFIOPCIDevice *vfio_pci = VFIO_PCI_DEVICE(pbdev->pdev);
+    if (ioctl(vfio_pci->vbasedev.fd, VFIO_DEVICE_RESET)) {
+        error_report("Failed to reset PCI device %s : %s ",
+                      vfio_pci->vbasedev.name, strerror(errno));
+    }
+}
+
 static void s390_pci_read_base(S390PCIBusDevice *pbdev,
                                struct vfio_device_info *info)
 {
diff --git a/include/hw/s390x/s390-pci-vfio.h b/include/hw/s390x/s390-pci-vfio.h
index c7886b63ea..38ccf445ea 100644
--- a/include/hw/s390x/s390-pci-vfio.h
+++ b/include/hw/s390x/s390-pci-vfio.h
@@ -21,5 +21,6 @@ void s390_pci_end_dma_count(S390pciState *s, S390PCIDMACount *cnt);
 bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh);
 void s390_pci_get_clp_info(S390PCIBusDevice *pbdev);
 bool s390_pci_setup_err_handler(S390PCIBusDevice *pbdev, Error **errp);
+void s390_pci_reset(S390PCIBusDevice *pbdev);
 
 #endif
-- 
2.43.0