linux-kernel - Re: [PATCH v2] asm-generic: Remove the parameters of the generate_guest_id function and modify the return type and modify the function name

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Message-ID: <Yy2KVM08HMiv46d6@liuwe-devbox-debian-v2>
Date:   Fri, 23 Sep 2022 10:28:36 +0000
From:   Wei Liu <wei.liu@...nel.org>
To:     Li kunyu <kunyu@...china.com>
Cc:     kys@...rosoft.com, haiyangz@...rosoft.com, sthemmin@...rosoft.com,
        wei.liu@...nel.org, decui@...rosoft.com, catalin.marinas@....com,
        will@...nel.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, arnd@...db.de, linux-hyperv@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH v2] asm-generic: Remove the parameters of the
 generate_guest_id function and modify the return type and modify the
 function name

Hi Kunyu

The subject line is far too long.

Please change it to

hyperv: simplify and rename generate_guest_id

On Tue, Sep 20, 2022 at 11:28:37AM +0800, Li kunyu wrote:
> The generate_guest_id function is more suitable for use after the
> following modifications.
> 1. Modify the type of the guest_id variable to u64, which is compatible
> with the caller.
> 2. Remove all parameters from the function, and write the parameter
> (LINUX_VERSION_CODE) passed in by the actual call into the function
> implementation.
> 3. Rename the function to make it clearly a Hyper-V related function,
> and modify it to hv_generate_guest_id.
> 
> v2:
>   Fix generate_guest_id to hv_generate_guest_id.

The patch version information shouldn't be part of the commit message.
You can use scissors to separate them

---8<---
 v2: ...

When the patch gets applied, text after the scissors will be stripped
automatically.

> 
> Signed-off-by: Li kunyu <kunyu@...china.com>

BTW, the previous patch was submitted by Li Zeming. Did you two agree on
who to take this forward?

> ---
>  arch/arm64/hyperv/mshyperv.c   |  2 +-
>  arch/x86/hyperv/hv_init.c      |  2 +-
>  include/asm-generic/mshyperv.h | 12 +++++-------
>  3 files changed, 7 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c
> index bbbe351e9045..3863fd226e0e 100644
> --- a/arch/arm64/hyperv/mshyperv.c
> +++ b/arch/arm64/hyperv/mshyperv.c
> @@ -38,7 +38,7 @@ static int __init hyperv_init(void)
>  		return 0;
>  
>  	/* Setup the guest ID */
> -	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
> +	guest_id = hv_generate_guest_id();
>  	hv_set_vpreg(HV_REGISTER_GUEST_OSID, guest_id);
>  
>  	/* Get the features and hints from Hyper-V */
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index 3de6d8b53367..93770791b858 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -426,7 +426,7 @@ void __init hyperv_init(void)
>  	 * 1. Register the guest ID
>  	 * 2. Enable the hypercall and register the hypercall page
>  	 */
> -	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
> +	guest_id = hv_generate_guest_id();
>  	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
>  
>  	/* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h
> index c05d2ce9b6cd..7f4a23cee56f 100644
> --- a/include/asm-generic/mshyperv.h
> +++ b/include/asm-generic/mshyperv.h
> @@ -25,6 +25,7 @@
>  #include <linux/nmi.h>
>  #include <asm/ptrace.h>
>  #include <asm/hyperv-tlfs.h>
> +#include <linux/version.h>
>  
>  struct ms_hyperv_info {
>  	u32 features;
> @@ -105,15 +106,12 @@ static inline u64 hv_do_rep_hypercall(u16 code, u16 rep_count, u16 varhead_size,
>  }
>  
>  /* Generate the guest OS identifier as described in the Hyper-V TLFS */
> -static inline  __u64 generate_guest_id(__u64 d_info1, __u64 kernel_version,
> -				       __u64 d_info2)
> +static inline  u64 hv_generate_guest_id(void)
                ^^
		There are two spaces. We only need one.

I know it is not introduced by you, but since you're modifying the code
anyway, you may as well drop the extraneous space.

>  {
> -	__u64 guest_id = 0;
> +	u64 guest_id;
>  
> -	guest_id = (((__u64)HV_LINUX_VENDOR_ID) << 48);
> -	guest_id |= (d_info1 << 48);
> -	guest_id |= (kernel_version << 16);
> -	guest_id |= d_info2;
> +	guest_id = (((u64)HV_LINUX_VENDOR_ID) << 48);
> +	guest_id |= (((u64)LINUX_VERSION_CODE) << 16);
>  
>  	return guest_id;
>  }
> -- 
> 2.18.2
>