Re: [PATCH 2/9] arm/domain: Get rid of READ/WRITE_SYSREG32

[Julien Grall <julien@xen.org>]

Hi Michal,

On 20/04/2021 08:08, Michal Orzel wrote:
> AArch64 system registers are 64bit whereas AArch32 ones
> are 32bit or 64bit. MSR/MRS are expecting 64bit values thus
> we should get rid of helpers READ/WRITE_SYSREG32
> in favour of using READ/WRITE_SYSREG.
> We should also use register_t type when reading sysregs
> which can correspond to uint64_t or uint32_t.
> Even though many AArch64 sysregs have upper 32bit reserved
> it does not mean that they can't be widen in the future.
> 
> Modify type of registers: actlr, cntkctl to register_t.

ACTLR is implementation defined, so in theory there might already bits 
already defined in the range [32:63]. So I would consider to split it 
from the patch so we can backport it.

> 
> Signed-off-by: Michal Orzel <michal.orzel@arm.com>
> ---
>   xen/arch/arm/domain.c        | 20 ++++++++++----------
>   xen/include/asm-arm/domain.h |  4 ++--
>   2 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index bdd3d3e5b5..c021a03c61 100644
> --- a/xen/arch/arm/domain.c
> +++ b/xen/arch/arm/domain.c
> @@ -113,13 +113,13 @@ static void ctxt_switch_from(struct vcpu *p)
>       p->arch.tpidr_el1 = READ_SYSREG(TPIDR_EL1);
>   
>       /* Arch timer */
> -    p->arch.cntkctl = READ_SYSREG32(CNTKCTL_EL1);
> +    p->arch.cntkctl = READ_SYSREG(CNTKCTL_EL1);
>       virt_timer_save(p);
>   
>       if ( is_32bit_domain(p->domain) && cpu_has_thumbee )
>       {
> -        p->arch.teecr = READ_SYSREG32(TEECR32_EL1);
> -        p->arch.teehbr = READ_SYSREG32(TEEHBR32_EL1);
> +        p->arch.teecr = READ_SYSREG(TEECR32_EL1);
> +        p->arch.teehbr = READ_SYSREG(TEEHBR32_EL1);

It feels strange you converted cntkctl and actlr to use register_t but 
not teecr and teehbr. Can you explain why?

Cheers,

-- 
Julien Grall