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From: Michal Orzel <michal.orzel@arm.com>
To: Julien Grall <julien@xen.org>, xen-devel@lists.xenproject.org
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>,
	bertrand.marquis@arm.com
Subject: Re: [PATCH 2/9] arm/domain: Get rid of READ/WRITE_SYSREG32
Date: Wed, 21 Apr 2021 09:36:18 +0200	[thread overview]
Message-ID: <fabfcd90-a46b-c496-2db4-258c47d0991f@arm.com> (raw)
In-Reply-To: <80f89abe-d81f-8b56-583c-470289abae0b@xen.org>

Hi Julien,

On 20.04.2021 15:12, Julien Grall wrote:
> 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.
> 
You mean not to touch it at all in this series or to create a seperate patch only for ACTLR?
>>
>> 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?
> 
Because thumbee and its registers do not appear in any of ARMv8 ARM version.
This means that this code could be protected even with #ifdef CONFIG_ARM_32 as AArch64 do not have them.
> Cheers,
> 
Cheers,
Michal


  reply	other threads:[~2021-04-21  7:37 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-04-20  7:08 [PATCH 0/9] xen/arm64: Get rid of READ/WRITE_SYSREG32 Michal Orzel
2021-04-20  7:08 ` [PATCH 1/9] arm64/vfp: " Michal Orzel
2021-04-20 13:04   ` Julien Grall
2021-04-20  7:08 ` [PATCH 2/9] arm/domain: " Michal Orzel
2021-04-20 13:12   ` Julien Grall
2021-04-21  7:36     ` Michal Orzel [this message]
2021-04-21 10:20       ` Julien Grall
2021-04-20  7:08 ` [PATCH 3/9] arm/gic: " Michal Orzel
2021-04-20 13:28   ` Julien Grall
2021-04-21  7:48     ` Michal Orzel
2021-04-21 10:21       ` Julien Grall
2021-04-20  7:08 ` [PATCH 4/9] arm/p2m: " Michal Orzel
2021-04-20 13:31   ` Julien Grall
2021-04-20  7:08 ` [PATCH 5/9] arm/mm: " Michal Orzel
2021-04-20 13:37   ` Julien Grall
2021-04-22 11:47     ` Michal Orzel
2021-04-22 13:40       ` Julien Grall
2021-04-20  7:08 ` [PATCH 6/9] arm/page: " Michal Orzel
2021-04-21 15:11   ` Julien Grall
2021-04-20  7:08 ` [PATCH 7/9] arm/time,vtimer: " Michal Orzel
2021-04-21 16:01   ` Julien Grall
2021-04-20  7:08 ` [PATCH 8/9] arm: Change type of hsr to register_t Michal Orzel
2021-04-21 19:02   ` Julien Grall
2021-04-20  7:08 ` [PATCH 9/9] xen/arm64: Remove READ/WRITE_SYSREG32 helper macros Michal Orzel
2021-04-21 19:16   ` Julien Grall
2021-04-27  7:16     ` Michal Orzel
2021-04-27  8:30       ` Julien Grall

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