[PATCH v1 4/4] s390x/pci: Reset a device in error state

[Farhan Ali]

For passthrough devices in error state, for a guest driven
reset of the device we can attempt a hot reset to recover the
device. A hot 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 <al...@linux.ibm.com>
---
 hw/s390x/s390-pci-bus.c          | 7 +++++++
 hw/s390x/s390-pci-vfio.c         | 6 ++++++
 include/hw/s390x/s390-pci-vfio.h | 2 ++
 3 files changed, 15 insertions(+)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index af42eb9938..c9c2d775f0 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -1493,6 +1493,8 @@ 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;
@@ -1505,6 +1507,11 @@ 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.c b/hw/s390x/s390-pci-vfio.c
index ceee342f4a..4ec5e2cd95 100644
--- a/hw/s390x/s390-pci-vfio.c
+++ b/hw/s390x/s390-pci-vfio.c
@@ -168,6 +168,12 @@ static void s390_pci_err_handler(VFIOPCIDevice *vfio_pci)
     return;
 }
 
+void s390_pci_reset(S390PCIBusDevice *pbdev)
+{
+    VFIOPCIDevice *vfio_pci = container_of(pbdev->pdev, VFIOPCIDevice, pdev);
+    ioctl(vfio_pci->vbasedev.fd, VFIO_DEVICE_RESET);
+}
+
 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 66b274293c..c28dafeed8 100644
--- a/include/hw/s390x/s390-pci-vfio.h
+++ b/include/hw/s390x/s390-pci-vfio.h
@@ -23,6 +23,7 @@ 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);
 void s390_pci_setup_err_handler(S390PCIBusDevice *pbdev);
+void s390_pci_reset(S390PCIBusDevice *pbdev);
 #else
 static inline bool s390_pci_update_dma_avail(int fd, unsigned int *avail)
 {
@@ -41,6 +42,7 @@ static inline bool s390_pci_get_host_fh(S390PCIBusDevice 
*pbdev, uint32_t *fh)
 }
 static inline void s390_pci_get_clp_info(S390PCIBusDevice *pbdev) { }
 static inline void s390_pci_setup_err_handler(S390PCIBusDevice *pbdev) { }
+void s390_pci_reset(S390PCIBusDevice *pbdev) { }
 #endif
 
 #endif
-- 
2.43.0