Re: [Qemu-devel] [PATCH v2 14/18] nvdimm: support NFIT_CMD_IMPLEMENTED function

[Xiao Guangrong]

On 08/26/2015 12:23 AM, Stefan Hajnoczi wrote:
> On Fri, Aug 14, 2015 at 10:52:07PM +0800, Xiao Guangrong wrote:
> > @@ -306,6 +354,18 @@ struct dsm_buffer {
> >   static ram_addr_t dsm_addr;
> >   static size_t dsm_size;
> >
> > +struct cmd_out_implemented {
>
> QEMU coding style uses typedef struct {} CamelCase.  Please follow this
> convention in all user-defined structs (see ./CODING_STYLE).

Okay, will adjust all the defines in the next version.

> >   static void dsm_write(void *opaque, hwaddr addr,
> >                         uint64_t val, unsigned size)
> >   {
> > +    struct MemoryRegion *dsm_ram_mr = opaque;
> > +    struct dsm_buffer *dsm;
> > +    struct dsm_out *out;
> > +    void *buf;
> > +
> >       assert(val == NOTIFY_VALUE);
>
> The guest should not be able to cause an abort(3).  If val !=
> NOTIFY_VALUE we can do nvdebug() and then return.

The ACPI code and emulation code both are from qemu, if that happens,
it's really a bug, aborting the VM is better than throwing a debug
message under this case to avoid potential data corruption.

> > +
> > +    buf = memory_region_get_ram_ptr(dsm_ram_mr);
> > +    dsm = buf;
> > +    out = buf;
> > +
> > +    le32_to_cpus(&dsm->handle);
> > +    le32_to_cpus(&dsm->arg1);
> > +    le32_to_cpus(&dsm->arg2);
>
> Can SMP guests modify DSM RAM while this thread is running?
>
> We must avoid race conditions.  It's probably better to copy in data
> before byte-swapping or checking input values.

Yes, my mistake, will fix.