Re: [Qemu-devel] [PATCH] hw/i386: fix nvdimm check error path

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jun 16, 2017 at 02:19:56PM +0100, Stefan Hajnoczi wrote:
> On Fri, Jun 09, 2017 at 04:16:15PM +0100, Stefan Hajnoczi wrote:
> > Commit e987c37aee1752177906847630d32477da57e705 ("hw/i386: check if
> > nvdimm is enabled before plugging") introduced a check to reject nvdimm
> > hotplug if -machine pc,nvdimm=on was not given.
> > 
> > This check executes after pc_dimm_memory_plug() has already completed
> > and does not reverse the effect of this function in the case of failure.
> > 
> > Perform the check before calling pc_dimm_memory_plug().  This fixes the
> > following abort:
> > 
> >   $ qemu -M accel=kvm -m 1G,slots=4,maxmem=8G \
> >          -object memory-backend-file,id=mem1,share=on,mem-path=nvdimm.dat,size=1G
> >   (qemu) device_add nvdimm,memdev=mem1
> >   nvdimm is not enabled: missing 'nvdimm' in '-M'
> >   (qemu) device_add nvdimm,memdev=mem1
> >   Core dumped
> > 
> > The backtrace is:
> > 
> >   #0  0x00007fffdb5b191f in raise () at /lib64/libc.so.6
> >   #1  0x00007fffdb5b351a in abort () at /lib64/libc.so.6
> >   #2  0x00007fffdb5a9da7 in __assert_fail_base () at /lib64/libc.so.6
> >   #3  0x00007fffdb5a9e52 in  () at /lib64/libc.so.6
> >   #4  0x000055555577a5fa in qemu_ram_set_idstr (new_block=0x555556747a00, name=<optimized out>, dev=dev@entry=0x555556705590) at qemu/exec.c:1709
> >   #5  0x0000555555a0fe86 in vmstate_register_ram (mr=mr@entry=0x55555673a0e0, dev=dev@entry=0x555556705590) at migration/savevm.c:2293
> >   #6  0x0000555555965088 in pc_dimm_memory_plug (dev=dev@entry=0x555556705590, hpms=hpms@entry=0x5555566bb0e0, mr=mr@entry=0x555556705630, align=<optimized out>, errp=errp@entry=0x7fffffffc660)
> >       at hw/mem/pc-dimm.c:110
> >   #7  0x000055555581d89b in pc_dimm_plug (errp=0x7fffffffc6c0, dev=0x555556705590, hotplug_dev=<optimized out>) at qemu/hw/i386/pc.c:1713
> >   #8  0x000055555581d89b in pc_machine_device_plug_cb (hotplug_dev=<optimized out>, dev=0x555556705590, errp=0x7fffffffc6c0) at qemu/hw/i386/pc.c:2004
> >   #9  0x0000555555914da6 in device_set_realized (obj=<optimized out>, value=<optimized out>, errp=0x7fffffffc7e8) at hw/core/qdev.c:926
> > 
> > Cc: Haozhong Zhang <haozhong.zhang@intel.com>
> > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> > ---
> >  hw/i386/pc.c | 14 ++++++++------
> >  1 file changed, 8 insertions(+), 6 deletions(-)
> 
> Michael: Do you want to take this through your tree?

Yes - it will be in the next pull.

> > 
> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> > index 5b8c6fb..db41cca 100644
> > --- a/hw/i386/pc.c
> > +++ b/hw/i386/pc.c
> > @@ -1692,6 +1692,7 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
> >      PCDIMMDeviceClass *ddc = PC_DIMM_GET_CLASS(dimm);
> >      MemoryRegion *mr = ddc->get_memory_region(dimm);
> >      uint64_t align = TARGET_PAGE_SIZE;
> > +    bool is_nvdimm = object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM);
> >  
> >      if (memory_region_get_alignment(mr) && pcmc->enforce_aligned_dimm) {
> >          align = memory_region_get_alignment(mr);
> > @@ -1703,17 +1704,18 @@ static void pc_dimm_plug(HotplugHandler *hotplug_dev,
> >          goto out;
> >      }
> >  
> > +    if (is_nvdimm && !pcms->acpi_nvdimm_state.is_enabled) {
> > +        error_setg(&local_err,
> > +                   "nvdimm is not enabled: missing 'nvdimm' in '-M'");
> > +        goto out;
> > +    }
> > +
> >      pc_dimm_memory_plug(dev, &pcms->hotplug_memory, mr, align, &local_err);
> >      if (local_err) {
> >          goto out;
> >      }
> >  
> > -    if (object_dynamic_cast(OBJECT(dev), TYPE_NVDIMM)) {
> > -        if (!pcms->acpi_nvdimm_state.is_enabled) {
> > -            error_setg(&local_err,
> > -                       "nvdimm is not enabled: missing 'nvdimm' in '-M'");
> > -            goto out;
> > -        }
> > +    if (is_nvdimm) {
> >          nvdimm_plug(&pcms->acpi_nvdimm_state);
> >      }
> >  
> > -- 
> > 2.9.4
> > 
> >