Re: [PATCH 1/2] hyperv: Fix pointer type for the output of the hypercall in get_vtl(void)

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

On 12/18/2024 6:45 PM, Wei Liu wrote:
> On Wed, Dec 18, 2024 at 12:54:20PM -0800, Roman Kisel wrote:
>> Commit bc905fa8b633 ("hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h")
>> changed the type of the output pointer to `struct hv_register_assoc` from
>> `struct hv_get_vp_registers_output`. That leads to an incorrect computation,
>> and leaves the system broken.
>>
>> Use the correct pointer type for the output of the GetVpRegisters hypercall.
>>
>> Fixes: bc905fa8b633 ("hyperv: Switch from hyperv-tlfs.h to hyperv/hvhdk.h")
> 
> This commit is not in the mainline kernel yet, so this tag is not
> needed.
Got it, thanks for the explanation!

> 
> It will most likely to be wrong since I will need to rebase the
> hyperv-next branch.
> 
> I can fold this patch into the original patch and leave your
> Signed-off-by there.
That would be great and appreciated very much, thank you!

> 
> Thanks,
> Wei.
Thank you,
Roman

> 
>> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
>> ---
>>   arch/x86/hyperv/hv_init.c   | 6 +++---
>>   include/hyperv/hvgdk_mini.h | 3 ---
>>   2 files changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
>> index 3cf2a227d666..c7185c6a290b 100644
>> --- a/arch/x86/hyperv/hv_init.c
>> +++ b/arch/x86/hyperv/hv_init.c
>> @@ -416,13 +416,13 @@ static u8 __init get_vtl(void)
>>   {
>>   	u64 control = HV_HYPERCALL_REP_COMP_1 | HVCALL_GET_VP_REGISTERS;
>>   	struct hv_input_get_vp_registers *input;
>> -	struct hv_register_assoc *output;
>> +	struct hv_get_vp_registers_output *output;
>>   	unsigned long flags;
>>   	u64 ret;
>>   
>>   	local_irq_save(flags);
>>   	input = *this_cpu_ptr(hyperv_pcpu_input_arg);
>> -	output = (struct hv_register_assoc *)input;
>> +	output = (struct hv_get_vp_registers_output *)input;
>>   
>>   	memset(input, 0, struct_size(input, names, 1));
>>   	input->partition_id = HV_PARTITION_ID_SELF;
>> @@ -432,7 +432,7 @@ static u8 __init get_vtl(void)
>>   
>>   	ret = hv_do_hypercall(control, input, output);
>>   	if (hv_result_success(ret)) {
>> -		ret = output->value.reg8 & HV_X64_VTL_MASK;
>> +		ret = output->as64.low & HV_X64_VTL_MASK;
>>   	} else {
>>   		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
>>   		BUG();
>> diff --git a/include/hyperv/hvgdk_mini.h b/include/hyperv/hvgdk_mini.h
>> index db3d1aaf7330..0b1a10828f33 100644
>> --- a/include/hyperv/hvgdk_mini.h
>> +++ b/include/hyperv/hvgdk_mini.h
>> @@ -1107,7 +1107,6 @@ union hv_register_value {
>>   	union hv_x64_pending_interruption_register pending_interruption;
>>   };
>>   
>> -#if defined(CONFIG_ARM64)
>>   /* HvGetVpRegisters returns an array of these output elements */
>>   struct hv_get_vp_registers_output {
>>   	union {
>> @@ -1124,8 +1123,6 @@ struct hv_get_vp_registers_output {
>>   	};
>>   };
>>   
>> -#endif /* CONFIG_ARM64 */
>> -
>>   struct hv_register_assoc {
>>   	u32 name;			/* enum hv_register_name */
>>   	u32 reserved1;
>> -- 
>> 2.34.1
>>

-- 
Thank you,
Roman