Re: [PATCH] x86/hyper-v: define structures from TLFS as packed

[Vitaly Kuznetsov]

Thomas Gleixner <tglx@xxxxxxxxxxxxx> writes:

> On Fri, 30 Nov 2018, Vitaly Kuznetsov wrote:
>
>> Subject: x86/hyper-v: define structures from TLFS as packed
>
> Please start the first word after the prefix colon with an uppercase
> letter. Also structures from TLFS doesn't make sense to me. Something like
> this:
>
> Subject: x86/hyper-v: Mark TLFS structures packed
>
>> Without 'packed' compiler is free to add optimization paddings and re-order
>> structure fields for randomization/optimization. And structures from
>
> s/And/As/ ?
>
>> hyperv-tlfs.h are used for hypervisor-guest communication, we need to
>> ultimately forbid such practices.
>
> That whole paragraph reads a bit strange. Something like:
>
>   The TLFS structures are used for hypervisor-guest communication and must
>   exactly meet the specification.
>
>   Compilers can add alignment padding to structures or reorder struct
>   members for randomization and optimization, which would break the
>   hypervisor ABI.
>
>   Mark the structures as packed to prevent this.
>
> Hmm?

Sure, will do v2!

>
>> Suggested-by: Nadav Amit <nadav.amit@xxxxxxxxx>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
>
> Other than that: Acked-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>

Thanks!

-- 
Vitaly