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

[Stefan Hajnoczi]

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>, address@hidden) at qemu/exec.c:1709
>   #5  0x0000555555a0fe86 in vmstate_register_ram (address@hidden, 
> address@hidden) at migration/savevm.c:2293
>   #6  0x0000555555965088 in pc_dimm_memory_plug (address@hidden, 
> address@hidden, address@hidden, align=<optimized out>, address@hidden)
>       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 <address@hidden>
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> ---
>  hw/i386/pc.c | 14 ++++++++------
>  1 file changed, 8 insertions(+), 6 deletions(-)

Michael: Do you want to take this through your tree?

> 
> 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
> 
>

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