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From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
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Date: Wed, 26 Aug 2015 18:46:35 +0800
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Subject: Re: [Qemu-devel] [PATCH v2 14/18] nvdimm: support
	NFIT_CMD_IMPLEMENTED function
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: ehabkost@redhat.com, kvm@vger.kernel.org, mst@redhat.com, gleb@kernel.org, mtosatti@redhat.com, qemu-devel@nongnu.org, stefanha@redhat.com, imammedo@redhat.com, pbonzini@redhat.com, rth@twiddle.net



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.