Re: [Xen-devel] [PATCH 2/2] x86/xpti: Don't leak TSS-adjacent percpu data via Meltdown

[Julien Grall <julien.grall@xxxxxxx>]

Hi,

On 26/07/2019 16:19, Roger Pau Monné wrote:
> On Fri, Jul 26, 2019 at 03:45:22PM +0100, Andrew Cooper wrote:
> > On 26/07/2019 15:38, Roger Pau Monné wrote:
> > > On Fri, Jul 26, 2019 at 02:52:40PM +0100, Andrew Cooper wrote:
> > There is no way to do this inside DEFINE_PER_CPU_PAGE_ALIGNED(), because
> > we can't break the type apart to insert __aligned() in the middle.
> And doing something like:
>
> #define DEFINE_PER_CPU_PAGE_ALIGNED(type, name) \
>      __DEFINE_PER_CPU(type, _##name, .page_aligned) __aligned(PAGE_SIZE)
>
> Won't work either I guess?
>
> I just find it unconformable to have to specify the aligned
> attribute in every usage of DEFINE_PER_CPU_PAGE_ALIGNED.
I was about to comment the same on patch #1 and decided to look at one of the 
caller first.
Because of the name, I was expecting the macro to actually do the alignment for 
you as well.
If it is not possible, then I think we should add a comment so developers know 
they have to add the page-alignment themselves.
Cheers,

--
Julien Grall

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