Re: [PATCH v6 03/11] arm64: realm: Query IPA size from the RMM

[Steven Price <steven.price@arm.com>]

On 15/10/2024 04:55, Gavin Shan wrote:
> On 10/5/24 12:42 AM, Steven Price wrote:
>> The top bit of the configured IPA size is used as an attribute to
>> control whether the address is protected or shared. Query the
>> configuration from the RMM to assertain which bit this is.
>>
>> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
>> Reviewed-by: Gavin Shan <gshan@redhat.com>
>> Co-developed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>> Changes since v4:
>>   * Make PROT_NS_SHARED check is_realm_world() to reduce impact on
>>     non-CCA systems.
>> Changes since v2:
>>   * Drop unneeded extra brackets from PROT_NS_SHARED.
>>   * Drop the explicit alignment from 'config' as struct realm_config now
>>     specifies the alignment.
>> ---
>>   arch/arm64/include/asm/pgtable-prot.h | 4 ++++
>>   arch/arm64/include/asm/rsi.h          | 2 +-
>>   arch/arm64/kernel/rsi.c               | 8 ++++++++
>>   3 files changed, 13 insertions(+), 1 deletion(-)
>>
> 
> [...]
> 
>> diff --git a/arch/arm64/kernel/rsi.c b/arch/arm64/kernel/rsi.c
>> index 9bf757b4b00c..a6495a64d9bb 100644
>> --- a/arch/arm64/kernel/rsi.c
>> +++ b/arch/arm64/kernel/rsi.c
>> @@ -8,6 +8,11 @@
>>   #include <linux/psci.h>
>>   #include <asm/rsi.h>
>>   +struct realm_config config;
>> +
> 
> Nit: I think this variable is file-scoped since it has a generic name.
> In this case, 'static' is needed to match with the scope.

Good spot - it should definitely be static.

Thanks,
Steve

>> +unsigned long prot_ns_shared;
>> +EXPORT_SYMBOL(prot_ns_shared);
>> +
>>   DEFINE_STATIC_KEY_FALSE_RO(rsi_present);
>>   EXPORT_SYMBOL(rsi_present);
>>   @@ -67,6 +72,9 @@ void __init arm64_rsi_init(void)
>>           return;
>>       if (!rsi_version_matches())
>>           return;
>> +    if (WARN_ON(rsi_get_realm_config(&config)))
>> +        return;
>> +    prot_ns_shared = BIT(config.ipa_bits - 1);
>>         arm64_rsi_setup_memory();
>>   
> 
> Thanks,
> Gavin
>