Re: [PATCH v2 02/10] arm/domain: Get rid of READ/WRITE_SYSREG32

[Julien Grall <julien@xxxxxxx>]

Hi Michal,

On 27/04/2021 10:35, Michal Orzel wrote:
> AArch64 registers are 64bit whereas AArch32 registers
> 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 registers have upper 32bit reserved
> it does not mean that they can't be widen in the future.
>
> Modify type of register cntkctl to register_t.
> Modify accesses to thumbee registers to use READ/WRITE_SYSREG.
> No need to change type of thumbee registers to register_t as they
> only exist on arm32.
This is a bit ambiguous, I think in this context you mean it is only 
usable by 32-bit domain but should really be only accessed on Armv7 as 
they were restrospectively dropped on Armv8.
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> ---
> Changes since v1:
> -Move modification of ACTLR into seperate patch
> ---
>   xen/arch/arm/domain.c        | 18 +++++++++---------
>   xen/include/asm-arm/domain.h |  2 +-
>   2 files changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> index bdd3d3e5b5..621f518b83 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);
>       }
>   
>   #ifdef CONFIG_ARM_32
> @@ -175,7 +175,7 @@ static void ctxt_switch_from(struct vcpu *p)
>   
>   static void ctxt_switch_to(struct vcpu *n)
>   {
> -    uint32_t vpidr;
> +    register_t vpidr;
>   
>       /* When the idle VCPU is running, Xen will always stay in hypervisor
>        * mode. Therefore we don't need to restore the context of an idle VCPU.
> @@ -183,8 +183,8 @@ static void ctxt_switch_to(struct vcpu *n)
>       if ( is_idle_vcpu(n) )
>           return;
>   
> -    vpidr = READ_SYSREG32(MIDR_EL1);
> -    WRITE_SYSREG32(vpidr, VPIDR_EL2);
> +    vpidr = READ_SYSREG(MIDR_EL1);
> +    WRITE_SYSREG(vpidr, VPIDR_EL2);
>       WRITE_SYSREG(n->arch.vmpidr, VMPIDR_EL2);
>   
>       /* VGIC */
> @@ -257,8 +257,8 @@ static void ctxt_switch_to(struct vcpu *n)
>   
>       if ( is_32bit_domain(n->domain) && cpu_has_thumbee )
>       {
> -        WRITE_SYSREG32(n->arch.teecr, TEECR32_EL1);
> -        WRITE_SYSREG32(n->arch.teehbr, TEEHBR32_EL1);
> +        WRITE_SYSREG(n->arch.teecr, TEECR32_EL1);
> +        WRITE_SYSREG(n->arch.teehbr, TEEHBR32_EL1);
>       }
>   
>   #ifdef CONFIG_ARM_32
> @@ -274,7 +274,7 @@ static void ctxt_switch_to(struct vcpu *n)
>   
>       /* This is could trigger an hardware interrupt from the virtual
>        * timer. The interrupt needs to be injected into the guest. */
> -    WRITE_SYSREG32(n->arch.cntkctl, CNTKCTL_EL1);
> +    WRITE_SYSREG(n->arch.cntkctl, CNTKCTL_EL1);
>       virt_timer_restore(n);
>   }
>   
> diff --git a/xen/include/asm-arm/domain.h b/xen/include/asm-arm/domain.h
> index 0a74df9931..c6b59ee755 100644
> --- a/xen/include/asm-arm/domain.h
> +++ b/xen/include/asm-arm/domain.h
> @@ -190,7 +190,7 @@ struct arch_vcpu
>       struct vgic_cpu vgic;
>   
>       /* Timer registers  */
> -    uint32_t cntkctl;
> +    register_t cntkctl;
>   
>       struct vtimer phys_timer;
>       struct vtimer virt_timer;
--
Julien Grall