[PATCH v2 3/4] s390x/pci: Add PCI error handling for vfio pci devices

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

Add an s390x specific callback for vfio error handling. For s390x pci devices,
we have platform specific error information. We need to retrieve this error
information for passthrough devices. This is done via a memory region which
exposes that information.

Once this error information is retrieved we can then inject an error into
the guest, and let the guest drive the recovery.

Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
---
 hw/s390x/s390-pci-bus.c          |  5 +++
 hw/s390x/s390-pci-vfio.c         | 76 ++++++++++++++++++++++++++++++++
 include/hw/s390x/s390-pci-bus.h  |  1 +
 include/hw/s390x/s390-pci-vfio.h |  2 +
 4 files changed, 84 insertions(+)

diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
index f87d2748b6..af42eb9938 100644
--- a/hw/s390x/s390-pci-bus.c
+++ b/hw/s390x/s390-pci-bus.c
@@ -158,6 +158,8 @@ static void s390_pci_perform_unplug(S390PCIBusDevice *pbdev)
 {
     HotplugHandler *hotplug_ctrl;
 
+    qemu_mutex_destroy(&pbdev->err_handler_lock);
+
     if (pbdev->pft == ZPCI_PFT_ISM) {
         notifier_remove(&pbdev->shutdown_notifier);
     }
@@ -1140,6 +1142,7 @@ static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
         pbdev->iommu->pbdev = pbdev;
         pbdev->state = ZPCI_FS_DISABLED;
         set_pbdev_info(pbdev);
+        qemu_mutex_init(&pbdev->err_handler_lock);
 
         if (object_dynamic_cast(OBJECT(dev), "vfio-pci")) {
             /*
@@ -1164,6 +1167,8 @@ static void s390_pcihost_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
             pbdev->iommu->dma_limit = s390_pci_start_dma_count(s, pbdev);
             /* Fill in CLP information passed via the vfio region */
             s390_pci_get_clp_info(pbdev);
+            /* Setup error handler for error recovery */
+            s390_pci_setup_err_handler(pbdev);
             if (!pbdev->interp) {
                 /* Do vfio passthrough but intercept for I/O */
                 pbdev->fh |= FH_SHM_VFIO;
diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
index aaf91319b4..87ecd06a81 100644
--- a/hw/s390x/s390-pci-vfio.c
+++ b/hw/s390x/s390-pci-vfio.c
@@ -10,6 +10,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/error-report.h"
 
 #include <sys/ioctl.h>
 #include <linux/vfio.h>
@@ -103,6 +104,60 @@ void s390_pci_end_dma_count(S390pciState *s, S390PCIDMACount *cnt)
     }
 }
 
+static int s390_pci_get_feature_err(VFIOPCIDevice *vfio_pci,
+                                    struct vfio_device_feature_zpci_err *err)
+{
+    int ret;
+    uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature) +
+                              sizeof(struct vfio_device_feature_zpci_err),
+                              sizeof(uint64_t))] = {};
+    struct vfio_device_feature *feature = (struct vfio_device_feature *)buf;
+
+    feature->argsz = sizeof(buf);
+    feature->flags = VFIO_DEVICE_FEATURE_GET | VFIO_DEVICE_FEATURE_ZPCI_ERROR;
+    ret = vfio_pci->vbasedev.io_ops->device_feature(&vfio_pci->vbasedev,
+                                                     feature);
+
+    if (ret) {
+        error_report("Failed feature get VFIO_DEVICE_FEATURE_ZPCI_ERROR"
+                    " (rc=%d)", ret);
+        return ret;
+    }
+
+    memcpy(err, (struct vfio_device_feature_zpci_err *) feature->data,
+           sizeof(struct vfio_device_feature_zpci_err));
+    return 0;
+}
+
+static void s390_pci_err_handler(VFIOPCIDevice *vfio_pci)
+{
+    S390PCIBusDevice *pbdev;
+    struct vfio_device_feature_zpci_err err;
+    int ret;
+
+    pbdev = s390_pci_find_dev_by_target(s390_get_phb(),
+                                        DEVICE(&vfio_pci->pdev)->id);
+
+    QEMU_LOCK_GUARD(&pbdev->err_handler_lock);
+
+    ret = s390_pci_get_feature_err(vfio_pci, &err);
+    if (ret) {
+        return;
+    }
+
+    pbdev->state = ZPCI_FS_ERROR;
+    s390_pci_generate_error_event(err.pec, pbdev->fh, pbdev->fid, 0, 0);
+
+    while (err.pending_errors) {
+        ret = s390_pci_get_feature_err(vfio_pci, &err);
+        if (ret) {
+            return;
+        }
+        s390_pci_generate_error_event(err.pec, pbdev->fh, pbdev->fid, 0, 0);
+    }
+    return;
+}
+
 static void s390_pci_read_base(S390PCIBusDevice *pbdev,
                                struct vfio_device_info *info)
 {
@@ -369,3 +424,24 @@ void s390_pci_get_clp_info(S390PCIBusDevice *pbdev)
     s390_pci_read_util(pbdev, info);
     s390_pci_read_pfip(pbdev, info);
 }
+
+void s390_pci_setup_err_handler(S390PCIBusDevice *pbdev)
+{
+    int ret;
+    VFIOPCIDevice *vfio_pci =  container_of(pbdev->pdev, VFIOPCIDevice, pdev);
+    uint64_t buf[DIV_ROUND_UP(sizeof(struct vfio_device_feature),
+                              sizeof(uint64_t))] = {};
+    struct vfio_device_feature *feature = (struct vfio_device_feature *)buf;
+
+    feature->argsz = sizeof(buf);
+    feature->flags = VFIO_DEVICE_FEATURE_PROBE | VFIO_DEVICE_FEATURE_ZPCI_ERROR;
+
+    ret = vfio_pci->vbasedev.io_ops->device_feature(&vfio_pci->vbasedev,
+                                                     feature);
+
+    if (ret) {
+        info_report("Automated error recovery not available for passthrough device");
+        return;
+    }
+    vfio_pci->arch_err_handler = s390_pci_err_handler;
+}
diff --git a/include/hw/s390x/s390-pci-bus.h b/include/hw/s390x/s390-pci-bus.h
index 04944d4fed..3795e0bbfc 100644
--- a/include/hw/s390x/s390-pci-bus.h
+++ b/include/hw/s390x/s390-pci-bus.h
@@ -364,6 +364,7 @@ struct S390PCIBusDevice {
     bool forwarding_assist;
     bool aif;
     bool rtr_avail;
+    QemuMutex err_handler_lock;
     QTAILQ_ENTRY(S390PCIBusDevice) link;
 };
 
diff --git a/include/hw/s390x/s390-pci-vfio.h b/include/hw/s390x/s390-pci-vfio.h
index ae1b126ff7..66b274293c 100644
--- a/include/hw/s390x/s390-pci-vfio.h
+++ b/include/hw/s390x/s390-pci-vfio.h
@@ -22,6 +22,7 @@ S390PCIDMACount *s390_pci_start_dma_count(S390pciState *s,
 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);
 #else
 static inline bool s390_pci_update_dma_avail(int fd, unsigned int *avail)
 {
@@ -39,6 +40,7 @@ static inline bool s390_pci_get_host_fh(S390PCIBusDevice *pbdev, uint32_t *fh)
     return false;
 }
 static inline void s390_pci_get_clp_info(S390PCIBusDevice *pbdev) { }
+static inline void s390_pci_setup_err_handler(S390PCIBusDevice *pbdev) { }
 #endif
 
 #endif
-- 
2.43.0