Re: [PATCH v3 1/7] arm64: hyperv: Use SMC to detect hypervisor presence

[Roman Kisel <romank@linux.microsoft.com>]

On 8/2/2024 6:21 PM, Wei Liu wrote:
> On Fri, Jul 26, 2024 at 03:59:04PM -0700, Roman Kisel wrote:
>> The arm64 Hyper-V startup path relies on ACPI to detect
>> running under a Hyper-V compatible hypervisor. That
>> doesn't work on non-ACPI systems.
>>
>> Hoist the ACPI detection logic into a separate function,
>> use the new SMC added recently to Hyper-V to use in the
>> non-ACPI case.
>>
>> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> 
> The change looks sensible.
> 
> Within one minor comment fixed below:
> 
> Acked-by: Wei Liu <wei.liu@kernel.org>
> 
> However I would also like to get an Acked-by or reivewed-by from someone
> who works on the ARM64 side of things -- Saurabh, Boqun, Srivatsa, and
> Jinank?
> 
>> ---
>>   arch/arm64/hyperv/mshyperv.c      | 36 ++++++++++++++++++++++++++-----
>>   arch/arm64/include/asm/mshyperv.h |  5 +++++
>>   2 files changed, 36 insertions(+), 5 deletions(-)
>>
> [...]
>> diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
>> index a975e1a689dd..a7a3586f7cb1 100644
>> --- a/arch/arm64/include/asm/mshyperv.h
>> +++ b/arch/arm64/include/asm/mshyperv.h
>> @@ -51,4 +51,9 @@ static inline u64 hv_get_msr(unsigned int reg)
>>   
>>   #include <asm-generic/mshyperv.h>
>>   
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_0	0x7948734d
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_1	0x56726570
> 
> Presumably these are ASCII codes for an identifier string, please
> provide comments to explain what they are.
> 
Michael posted a suggestion to change that altogether; will elaborate on 
the topic in the thread with Michael.

>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_2	0
>> +#define ARM_SMCCC_VENDOR_HYP_UID_HYPERV_REG_3	0
>> +
>>   #endif
>> -- 
>> 2.34.1
>>

-- 
Thank you,
Roman