Re: [PATCH] asm-generic/hyperv: Fix struct hv_message_header ordering

[Siddharth Chandrasekaran <sidcha@amazon.de>]

On Thu, Jul 29, 2021 at 04:56:38PM +0000, Wei Liu wrote:
> On Thu, Jul 29, 2021 at 04:26:54PM +0200, Siddharth Chandrasekaran wrote:
> > On Thu, Jul 29, 2021 at 02:07:05PM +0000, Wei Liu wrote:
> > > On Thu, Jul 29, 2021 at 03:52:46PM +0200, Vitaly Kuznetsov wrote:
> > > > Siddharth Chandrasekaran <sidcha@amazon.de> writes:
> > > >
> > > > > According to Hyper-V TLFS Version 6.0b, struct hv_message_header members
> > > > > should be defined in the order:
> > > > >
> > > > >     message_type, reserved, message_flags, payload_size
> > > > >
> > > > > but we have it defined in the order:
> > > > >
> > > > >     message_type, payload_size, message_flags, reserved
> > > > >
> > > > > that is, the payload_size and reserved members swapped.
> > > >
> > > > Indeed,
> > > >
> > > > typedef struct
> > > > {
> > > >       HV_MESSAGE_TYPE MessageType;
> > > >       UINT16 Reserved;
> > > >       HV_MESSAGE_FLAGS MessageFlags;
> > > >       UINT8 PayloadSize;
> > > >       union
> > > >       {
> > > >               UINT64 OriginationId;
> > > >               HV_PARTITION_ID Sender;
> > > >               HV_PORT_ID Port;
> > > >       };
> > > > } HV_MESSAGE_HEADER;
> > >
> > > Well. I think TLFS is wrong. Let me ask around.
> >
> > TBH, I hadn't considered that possibility :). I assumed it was a
> > regression on our side. But I spent some time tracing the history of that
> > struct all the way back to when it was in staging (in 2009) and now I'm
> > inclined to believe a later version of TLFS is at fault here.
> >
> > Based on what we decide in this thread, I will open an issue on the TLFS
> > GitHub repository.
> >
> 
> I have confirmation TLFS is wrong and shall be fixed. Feel free to open
> an issue on GitHub too.

Thanks for the confirmation, I created an issue [1] to track this.

~ Sid.

[1]: https://github.com/MicrosoftDocs/Virtualization-Documentation/issues/1624



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