[PATCH RFC 1/1] msix: add hmp interface to dump MSI-X info

[Dongli Zhang]

This patch is to add the HMP interface to dump MSI-X table and PBA, in
order to help diagnose the loss of IRQ issue in VM (e.g., if an MSI-X
vector is erroneously masked permanently). Here is the example with
vhost-scsi:

(qemu) info msix /machine/peripheral/vscsi0
MSI-X Table
0xfee01004 0x00000000 0x00000022 0x00000000
0xfee02004 0x00000000 0x00000023 0x00000000
0xfee01004 0x00000000 0x00000023 0x00000000
0xfee01004 0x00000000 0x00000021 0x00000000
0xfee02004 0x00000000 0x00000022 0x00000000
0x00000000 0x00000000 0x00000000 0x00000001
0x00000000 0x00000000 0x00000000 0x00000001
MSI-X PBA
0 0 0 0 0 0 0

Since the number of MSI-X entries is not determined and might be very
large, it is sometimes inappropriate to dump via QMP.

Therefore, this patch dumps MSI-X information only via HMP, which is
similar to the implementation of hmp_info_mem().

Cc: Jason Wang <jasowang@redhat.com>
Cc: Joe Jin <joe.jin@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
---
 hmp-commands-info.hx   | 13 +++++++++++
 hw/pci/msix.c          | 49 ++++++++++++++++++++++++++++++++++++++++++
 include/hw/pci/msix.h  |  2 ++
 include/monitor/hmp.h  |  1 +
 softmmu/qdev-monitor.c | 25 +++++++++++++++++++++
 5 files changed, 90 insertions(+)

diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index ab0c7aa5ee..cbd056442b 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -221,6 +221,19 @@ SRST
     Show PCI information.
 ERST
 
+    {
+        .name       = "msix",
+        .args_type  = "dev:s",
+        .params     = "dev",
+        .help       = "dump MSI-X information",
+        .cmd        = hmp_info_msix,
+    },
+
+SRST
+  ``info msix`` *dev*
+    Dump MSI-X information for device *dev*.
+ERST
+
 #if defined(TARGET_I386) || defined(TARGET_SH4) || defined(TARGET_SPARC) || \
     defined(TARGET_PPC) || defined(TARGET_XTENSA) || defined(TARGET_M68K)
     {
diff --git a/hw/pci/msix.c b/hw/pci/msix.c
index ae9331cd0b..a93d31da9f 100644
--- a/hw/pci/msix.c
+++ b/hw/pci/msix.c
@@ -22,6 +22,7 @@
 #include "sysemu/xen.h"
 #include "migration/qemu-file-types.h"
 #include "migration/vmstate.h"
+#include "monitor/monitor.h"
 #include "qemu/range.h"
 #include "qapi/error.h"
 #include "trace.h"
@@ -669,3 +670,51 @@ const VMStateDescription vmstate_msix = {
         VMSTATE_END_OF_LIST()
     }
 };
+
+static void msix_dump_table(Monitor *mon, PCIDevice *dev)
+{
+    int vector, i, offset;
+    uint32_t val;
+
+    monitor_printf(mon, "MSI-X Table\n");
+
+    for (vector = 0; vector < dev->msix_entries_nr; vector++) {
+        for (i = 0; i < 4; i++) {
+            offset = vector * PCI_MSIX_ENTRY_SIZE + i * 4;
+            val = pci_get_long(dev->msix_table + offset);
+
+            monitor_printf(mon, "0x%08x ", val);
+        }
+        monitor_printf(mon, "\n");
+    }
+}
+
+static void msix_dump_pba(Monitor *mon, PCIDevice *dev)
+{
+    int vector;
+
+    monitor_printf(mon, "MSI-X PBA\n");
+
+    for (vector = 0; vector < dev->msix_entries_nr; vector++) {
+        monitor_printf(mon, "%d ", !!msix_is_pending(dev, vector));
+
+        if (vector % 16 == 15) {
+            monitor_printf(mon, "\n");
+        }
+    }
+
+    if (vector % 16 != 15) {
+        monitor_printf(mon, "\n");
+    }
+}
+
+void msix_dump_info(Monitor *mon, PCIDevice *dev, Error **errp)
+{
+    if (!msix_present(dev)) {
+        error_setg(errp, "MSI-X not available");
+        return;
+    }
+
+    msix_dump_table(mon, dev);
+    msix_dump_pba(mon, dev);
+}
diff --git a/include/hw/pci/msix.h b/include/hw/pci/msix.h
index 4c4a60c739..10a4500295 100644
--- a/include/hw/pci/msix.h
+++ b/include/hw/pci/msix.h
@@ -47,6 +47,8 @@ int msix_set_vector_notifiers(PCIDevice *dev,
                               MSIVectorPollNotifier poll_notifier);
 void msix_unset_vector_notifiers(PCIDevice *dev);
 
+void msix_dump_info(Monitor *mon, PCIDevice *dev, Error **errp);
+
 extern const VMStateDescription vmstate_msix;
 
 #define VMSTATE_MSIX_TEST(_field, _state, _test) {                   \
diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
index 605d57287a..46e0efc213 100644
--- a/include/monitor/hmp.h
+++ b/include/monitor/hmp.h
@@ -36,6 +36,7 @@ void hmp_info_irq(Monitor *mon, const QDict *qdict);
 void hmp_info_pic(Monitor *mon, const QDict *qdict);
 void hmp_info_rdma(Monitor *mon, const QDict *qdict);
 void hmp_info_pci(Monitor *mon, const QDict *qdict);
+void hmp_info_msix(Monitor *mon, const QDict *qdict);
 void hmp_info_tpm(Monitor *mon, const QDict *qdict);
 void hmp_info_iothreads(Monitor *mon, const QDict *qdict);
 void hmp_quit(Monitor *mon, const QDict *qdict);
diff --git a/softmmu/qdev-monitor.c b/softmmu/qdev-monitor.c
index a9955b97a0..2a37d03fb7 100644
--- a/softmmu/qdev-monitor.c
+++ b/softmmu/qdev-monitor.c
@@ -19,6 +19,7 @@
 
 #include "qemu/osdep.h"
 #include "hw/sysbus.h"
+#include "hw/pci/msix.h"
 #include "monitor/hmp.h"
 #include "monitor/monitor.h"
 #include "monitor/qdev.h"
@@ -1006,3 +1007,27 @@ bool qmp_command_available(const QmpCommand *cmd, Error 
**errp)
     }
     return true;
 }
+
+void hmp_info_msix(Monitor *mon, const QDict *qdict)
+{
+    const char *name = qdict_get_str(qdict, "dev");
+    DeviceState *dev = find_device_state(name, NULL);
+    PCIDevice *pci_dev;
+    Error *err = NULL;
+
+    if (!dev) {
+        error_setg(&err, "Device %s not found", name);
+        goto exit;
+    }
+
+    if (!object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
+        error_setg(&err, "Not a PCI device");
+        goto exit;
+    }
+
+    pci_dev = PCI_DEVICE(dev);
+    msix_dump_info(mon, pci_dev, &err);
+
+exit:
+    hmp_handle_error(mon, err);
+}
-- 
2.17.1