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

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Julien,

On 27.04.2021 11:45, Julien Grall wrote:
> 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.
> 
Is the following ok for a v3?:
"
...
Modify type of register cntkctl to register_t.

Modify accesses to thumbee registers to use READ/WRITE_SYSREG.
Thumbee registers are only usable by a 32bit domain and in fact
should be only accessed on ARMv7 as they were retrospectively 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;
>>
>