Re: [Qemu-devel] [PATCH v3 4/9] {monitor, hw/pvrdma}: Expose device internals via monitor interface

[Yuval Shaia <yuval.shaia@oracle.com>]

On Fri, Mar 01, 2019 at 08:17:02AM +0100, Markus Armbruster wrote:
> Marcel Apfelbaum <marcel.apfelbaum@gmail.com> writes:
> 
> > Hi Yuval,
> >
> > On 2/27/19 4:06 PM, Yuval Shaia wrote:
> >> Allow interrogating device internals through HMP interface.
> >> The exposed indicators can be used for troubleshooting by developers or
> >> sysadmin.
> >> There is no need to expose these attributes to a management system (e.x.
> >> libvirt) because (1) most of them are not "device-management' related
> >> info and (2) there is no guarantee the interface is stable.
> >>
> >> Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
> >> ---
> >>   hmp-commands-info.hx      | 16 ++++++++
> >>   hw/rdma/rdma_backend.c    | 70 ++++++++++++++++++++++++++---------
> >>   hw/rdma/rdma_rm.c         |  7 ++++
> >>   hw/rdma/rdma_rm_defs.h    | 27 +++++++++++++-
> >>   hw/rdma/vmw/pvrdma.h      |  5 +++
> >>   hw/rdma/vmw/pvrdma_hmp.h  | 21 +++++++++++
> >>   hw/rdma/vmw/pvrdma_main.c | 77 +++++++++++++++++++++++++++++++++++++++
> >>   monitor.c                 | 10 +++++
> >>   8 files changed, 215 insertions(+), 18 deletions(-)
> >>   create mode 100644 hw/rdma/vmw/pvrdma_hmp.h
> >>
> >> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> >> index cbee8b944d..9153c33974 100644
> >> --- a/hmp-commands-info.hx
> >> +++ b/hmp-commands-info.hx
> >> @@ -524,6 +524,22 @@ STEXI
> >>   Show CPU statistics.
> >>   ETEXI
> >>   +#if defined(CONFIG_PVRDMA)
> >> +    {
> >> +        .name       = "pvrdmacounters",
> >> +        .args_type  = "",
> >> +        .params     = "",
> >> +        .help       = "show pvrdma device counters",
> >> +        .cmd        = hmp_info_pvrdmacounters,
> >> +    },
> >> +
> >> +STEXI
> >> +@item info pvrdmacounters
> >> +@findex info pvrdmacounters
> >> +Show pvrdma device counters.
> >> +ETEXI
> >> +#endif
> >> +
> >>   #if defined(CONFIG_SLIRP)
> >>       {
> >>           .name       = "usernet",
> [...]
> >> diff --git a/hw/rdma/vmw/pvrdma_main.c b/hw/rdma/vmw/pvrdma_main.c
> >> index b6061f4b6e..85101368c5 100644
> >> --- a/hw/rdma/vmw/pvrdma_main.c
> >> +++ b/hw/rdma/vmw/pvrdma_main.c
> >> @@ -14,6 +14,7 @@
> >>    */
> >>     #include "qemu/osdep.h"
> >> +#include "qemu/units.h"
> >>   #include "qapi/error.h"
> >>   #include "hw/hw.h"
> >>   #include "hw/pci/pci.h"
> >> @@ -25,6 +26,7 @@
> >>   #include "cpu.h"
> >>   #include "trace.h"
> >>   #include "sysemu/sysemu.h"
> >> +#include "monitor/monitor.h"
> >>     #include "../rdma_rm.h"
> >>   #include "../rdma_backend.h"
> >> @@ -32,10 +34,13 @@
> >>     #include <infiniband/verbs.h>
> >>   #include "pvrdma.h"
> >> +#include "pvrdma_hmp.h"
> >>   #include "standard-headers/rdma/vmw_pvrdma-abi.h"
> >>   #include "standard-headers/drivers/infiniband/hw/vmw_pvrdma/pvrdma_dev_api.h"
> >>   #include "pvrdma_qp_ops.h"
> >>   +GSList *devices;
> 
> "devices" is far too generic for an external identifier.  Are you
> missing a 'static' here?  Even if static, I'd recommend "rdma_devices".

Yep, thanks.

> 
> >> +
> >>   static Property pvrdma_dev_properties[] = {
> >>       DEFINE_PROP_STRING("netdev", PVRDMADev, backend_eth_device_name),
> >>       DEFINE_PROP_STRING("ibdev", PVRDMADev, backend_device_name),
> >> @@ -55,6 +60,71 @@ static Property pvrdma_dev_properties[] = {
> [...]
> >> +}
> >> +
> >> +void pvrdma_dump_counters(Monitor *mon)
> >> +{
> >> +    g_slist_foreach(devices, pvrdma_dump_device_counters, mon);
> >> +}
> 
> Note for later: does nothing when @devices is empty.

But that is fine, isn't it?

> 
> >> +
> >>   static void free_dev_ring(PCIDevice *pci_dev, PvrdmaRing *ring,
> >>                             void *ring_state)
> >>   {
> >> @@ -304,6 +374,8 @@ static void pvrdma_fini(PCIDevice *pdev)
> >>         rdma_info_report("Device %s %x.%x is down", pdev->name,
> >>                        PCI_SLOT(pdev->devfn), PCI_FUNC(pdev->devfn));
> >> +
> >> +    devices = g_slist_remove(devices, pdev);
> >>   }
> >>     static void pvrdma_stop(PVRDMADev *dev)
> >> @@ -394,6 +466,7 @@ static void pvrdma_regs_write(void *opaque, hwaddr addr, uint64_t val,
> >>           if (val == 0) {
> >>               trace_pvrdma_regs_write(addr, val, "REQUEST", "");
> >>               pvrdma_exec_cmd(dev);
> >> +            dev->stats.commands++;
> >>           }
> >>           break;
> >>       default:
> >> @@ -612,9 +685,13 @@ static void pvrdma_realize(PCIDevice *pdev, Error **errp)
> >>           goto out;
> >>       }
> >>   +    memset(&dev->stats, 0, sizeof(dev->stats));
> >> +
> >>       dev->shutdown_notifier.notify = pvrdma_shutdown_notifier;
> >>       qemu_register_shutdown_notifier(&dev->shutdown_notifier);
> >>   +    devices = g_slist_append(devices, pdev);
> >> +
> >>   out:
> >>       if (rc) {
> >>           pvrdma_fini(pdev);
> 
> Note for later: @devices contains the realized "pvrdma" devices.

This happens only when rc indicates an error and we jumped here before
adding the device to the list.

> 
> You could find these devices with object_child_foreach_recursive()
> instead of maintaining a separate list.

Hmmm...interesting.
I will check if it fits my needs and will change accordingly if yes.

> 
> >> diff --git a/monitor.c b/monitor.c
> >> index defa129319..53ecb5bc70 100644
> >> --- a/monitor.c
> >> +++ b/monitor.c
> >> @@ -85,6 +85,9 @@
> >>   #include "sysemu/iothread.h"
> >>   #include "qemu/cutils.h"
> >>   #include "tcg/tcg.h"
> >> +#ifdef CONFIG_PVRDMA
> >> +#include "hw/rdma/vmw/pvrdma_hmp.h"
> >> +#endif
> >>     #if defined(TARGET_S390X)
> >>   #include "hw/s390x/storage-keys.h"
> >> @@ -1362,6 +1365,13 @@ static void hmp_info_cpustats(Monitor *mon, const QDict *qdict)
> >>       cpu_dump_statistics(cs, (FILE *)mon, &monitor_fprintf, 0);
> >>   }
> >>   +#ifdef CONFIG_PVRDMA
> >> +static void hmp_info_pvrdmacounters(Monitor *mon, const QDict *qdict)
> >> +{
> >> +    pvrdma_dump_counters(mon);
> >
> > Compilation fails on archs with no PCI support:
> >
> >     /usr/bin/ld: monitor.o: in function `hmp_info_pvrdmacounters':
> >     /home/marcel/git/qemu/monitor.c:1371: undefined reference to
> > `pvrdma_dump_counters'
> >    collect2: error: ld returned 1 exit status
> >    make[1]: *** [Makefile:210: qemu-system-m68k] Error 1
> >
> >
> > The below patch solves it by adding a pci stub:
> >
> > diff --git a/hw/pci/pci-stub.c b/hw/pci/pci-stub.c
> > index b941a0e842..cab364f93d 100644
> > --- a/hw/pci/pci-stub.c
> > +++ b/hw/pci/pci-stub.c
> > @@ -26,6 +26,7 @@
> >  #include "qapi/qmp/qerror.h"
> >  #include "hw/pci/pci.h"
> >  #include "hw/pci/msi.h"
> > +#include "hw/rdma/vmw/pvrdma_hmp.h"
> >
> >  bool msi_nonbroken;
> >  bool pci_available;
> > @@ -53,3 +54,9 @@ uint16_t pci_requester_id(PCIDevice *dev)
> >      g_assert(false);
> >      return 0;
> >  }
> > +
> > +void pvrdma_dump_counters(Monitor *mon)
> > +{
> > +    monitor_printf(mon, "PVRDMA requires PCI support\n");
> > +}
> > +
> 
> When CONFIG_PCI is enabled, "info pvrdmacounters" does nothing when
> there are no "pvrdma" devices.
> 
> When CONFIG_PCI is disabled, there are no "pvrdma" devices.  Therefore,
> "info pvrdmacounters" should also do nothing then, shouldn't it?

Yeah, problem was in case that pvrdma was selected in ./configure phase but
platform does not have PCI -> CONFIG_PCI is diabeled -> pvrdma code is not
compiled -> pvrdma_dump_counters is missing in link phase.

If you have a better alternative then i'm fine, meanwhile i'm taking
Marcel's proposal.

> 
> > However you should include a generic rdma header as hw/rdma/rdma_hmp.h
> > and not a vmw specific one.
> >
> >
> > Thanks,
> > Marcel
> >
> >
> >> +}
> >> +#endif
> >> +
> >>   static void hmp_info_trace_events(Monitor *mon, const QDict *qdict)
> >>   {
> >>       const char *name = qdict_get_try_str(qdict, "name");
>