linux-kernel - Re: [PATCH 1/2] hyperv: Fix pointer type for the output of the hypercall in get

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Message-ID: <Z2OIsFUXcjVXpqtw@liuwe-devbox-debian-v2>
Date: Thu, 19 Dec 2024 02:45:04 +0000
From: Wei Liu <wei.liu@...nel.org>
To: Roman Kisel <romank@...ux.microsoft.com>
Cc: hpa@...or.com, kys@...rosoft.com, bp@...en8.de,
	dave.hansen@...ux.intel.com, decui@...rosoft.com,
	eahariha@...ux.microsoft.com, haiyangz@...rosoft.com,
	mingo@...hat.com, mhklinux@...look.com,
	nunodasneves@...ux.microsoft.com, tglx@...utronix.de,
	tiala@...rosoft.com, wei.liu@...nel.org,
	linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org,
	x86@...nel.org, apais@...rosoft.com, benhill@...rosoft.com,
	ssengar@...rosoft.com, sunilmut@...rosoft.com, vdso@...bites.dev
Subject: Re: [PATCH 1/2] hyperv: Fix pointer type for the output of the
 hypercall in get_vtl(void)

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.

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.

Thanks,
Wei.

> Signed-off-by: Roman Kisel <romank@...ux.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
>