Subject: Re: [PATCH v4 08/29] KVM: arm64: make kvm_at() take an OP_AT_*

From: Marc Zyngier <[email-masked]>
Date: Wed, 29 May 2024 16:46:23 +0100

On Fri, 03 May 2024 14:01:26 +0100,
Joey Gouly <[email-masked]> wrote:
> 
> To allow using newer instructions that current assemblers don't know about,
> replace the `at` instruction with the underlying SYS instruction.
> 
> Signed-off-by: Joey Gouly <[email-masked]>
> Cc: Marc Zyngier <[email-masked]>
> Cc: Oliver Upton <[email-masked]>
> Cc: Catalin Marinas <[email-masked]>
> Cc: Will Deacon <[email-masked]>
> ---
>  arch/arm64/include/asm/kvm_asm.h       | 3 ++-
>  arch/arm64/kvm/hyp/include/hyp/fault.h | 2 +-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> index 24b5e6b23417..ce65fd0f01b0 100644
> --- a/arch/arm64/include/asm/kvm_asm.h
> +++ b/arch/arm64/include/asm/kvm_asm.h
> @@ -10,6 +10,7 @@
>  #include <asm/hyp_image.h>
>  #include <asm/insn.h>
>  #include <asm/virt.h>
> +#include <asm/sysreg.h>

nit: include order.

>  
>  #define ARM_EXIT_WITH_SERROR_BIT  31
>  #define ARM_EXCEPTION_CODE(x)	  ((x) & ~(1U << ARM_EXIT_WITH_SERROR_BIT))
> @@ -261,7 +262,7 @@ extern u64 __kvm_get_mdcr_el2(void);
>  	asm volatile(							\
>  	"	mrs	%1, spsr_el2\n"					\
>  	"	mrs	%2, elr_el2\n"					\
> -	"1:	at	"at_op", %3\n"					\
> +	"1:	" __msr_s(at_op, "%3") "\n"				\
>  	"	isb\n"							\
>  	"	b	9f\n"						\
>  	"2:	msr	spsr_el2, %1\n"					\
> diff --git a/arch/arm64/kvm/hyp/include/hyp/fault.h b/arch/arm64/kvm/hyp/include/hyp/fault.h
> index 9e13c1bc2ad5..487c06099d6f 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/fault.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/fault.h
> @@ -27,7 +27,7 @@ static inline bool __translate_far_to_hpfar(u64 far, u64 *hpfar)
>  	 * saved the guest context yet, and we may return early...
>  	 */
>  	par = read_sysreg_par();
> -	if (!__kvm_at("s1e1r", far))
> +	if (!__kvm_at(OP_AT_S1E1R, far))
>  		tmp = read_sysreg_par();
>  	else
>  		tmp = SYS_PAR_EL1_F; /* back to the guest */

Reviewed-by: Marc Zyngier <[email-masked]>

	M.

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