[PATCH v3 04/18] KVM: arm64: Restrict symbol aliasing to outside nVHE

[Marc Zyngier]

Hi Andrew,

On Thu, 03 Sep 2020 14:52:53 +0100,
Andrew Scull <ascull at google.com> wrote:
> 
> nVHE symbols are prefixed but this is sometimes hidden from the host by
> aliasing the non-prefixed symbol to the prefixed version with a macro.
> This runs into problems if nVHE tries to use the symbol as it becomes
> doubly prefixed. Avoid this by omitting the aliasing macro for nVHE.
> 
> Cc: David Brazdil <dbrazdil at google.com>
> Signed-off-by: Andrew Scull <ascull at google.com>
> ---
>  arch/arm64/include/asm/kvm_asm.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 6f98fbd0ac81..6f9c4162a764 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -99,8 +99,11 @@ struct kvm_s2_mmu;
>  
>  DECLARE_KVM_NVHE_SYM(__kvm_hyp_init);
>  DECLARE_KVM_HYP_SYM(__kvm_hyp_vector);
> +
> +#ifndef __KVM_NVHE_HYPERVISOR__
>  #define __kvm_hyp_init		CHOOSE_NVHE_SYM(__kvm_hyp_init)
>  #define __kvm_hyp_vector	CHOOSE_HYP_SYM(__kvm_hyp_vector)
> +#endif

Hmmm. Why do we limit this to these two symbols instead of making it a
property of the "CHOOSE_*" implementation?

The use of CHOOSE_HYP_SYM is already forbidden in the EL2 code (see
how any symbol results in __nvhe_undefined_symbol being emitted). Does
anything break if we have:

#define CHOOSE_NVHE_SYM(x)	x

when __KVM_NVHE_HYPERVISOR__ is defined?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.