Re: [Xen-devel] [PATCH] x86: properly gate clearing of PKU feature

[Jan Beulich <jbeulich@xxxxxxxx>]

On 29.08.2019 12:46, Andrew Cooper wrote:
> On 29/08/2019 10:27, Jan Beulich wrote:
>> setup_clear_cpu_cap() is __init and hence may not be called post-boot.
>> Note that opt_pku nevertheless is not getting __initdata added - see
>> e.g. commit 43fa95ae6a ("mm: make opt_bootscrub non-init").
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> 
> However, I'm tempted to suggest that this logic disappears entirely. 
> Given that we don't support it for PV guests, and can't without taking a
> CR4 write on toggle_kernel_mode(), all this actually controls is whether
> the bit finds its way into the HVM max policy.

Well, if you mean replacing opt_pku by an addition to
parse_xen_cpuid(), then I'll be happy to do that as a follow-on.
If there is another direction you've been considering, then
you'd have to at least outline it.

Jan

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