Re: [PATCH 0/3] KVM: arm64: Ask the compiler to __always_inline functions used by KVM at HYP

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Hi Ard,

On 20/02/2020 17:04, Ard Biesheuvel wrote:
> On Thu, 20 Feb 2020 at 17:58, James Morse <james.morse@xxxxxxx> wrote:
>> It turns out KVM relies on the inline hint being honoured by the compiler
>> in quite a few more places than expected. Something about the Shadow Call
>> Stack support[0] causes the compiler to avoid inline-ing and to place
>> these functions outside the __hyp_text. This ruins KVM's day.
>>
>> Add the simon-says __always_inline annotation to all the static
>> inlines that KVM calls from HYP code.

> This isn't quite as yuck as I expected, fortunately, but it does beg
> the question whether we shouldn't simply map the entire kernel at EL2
> instead?

If the kernel is big enough to need internal veneers (the 128M range?), these would
certainly go horribly wrong because its running somewhere other than the relocation-time
address. We would need a way of telling the linker to keep the bits of KVM close together...


Thanks,

James
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