Re: [PATCH v5 2/5] hyperv: Fix pointer type in get_vtl(void)

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

On 12/30/2024 10:09 AM, 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.
> 
> Signed-off-by: Roman Kisel <romank@linux.microsoft.com>
> ---
>  arch/x86/hyperv/hv_init.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 9e5e8328df6b..f82d1aefaa8a 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_output_get_vp_registers *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_output_get_vp_registers *)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->values[0].reg8 & HV_X64_VTL_MASK;
>  	} else {
>  		pr_err("Failed to get VTL(error: %lld) exiting...\n", ret);
>  		BUG();

Reviewed-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>