linux-kernel - Re: [PATCH linux-next v2] KVM: SVM: Remove the unneeded result variable

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:   Mon, 22 Aug 2022 16:00:42 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     cgel.zte@...il.com
Cc:     pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, dave.hansen@...ux.intel.com, x86@...nel.org,
        hpa@...or.com, kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        ye xingchen <ye.xingchen@....com.cn>
Subject: Re: [PATCH linux-next v2] KVM: SVM: Remove the unneeded result
 variable

On Mon, Aug 22, 2022, cgel.zte@...il.com wrote:
> From: ye xingchen <ye.xingchen@....com.cn>
> 
> Return the value from sev_guest_activate(&activate, error) and
> sev_issue_cmd_external_user(f.file, id, data, error) directly
> instead of storing it in another redundant variable.And also change
> the position of handle and asid to simplify the code.
> 
> Signed-off-by: ye xingchen <ye.xingchen@....com.cn>
> ---
> v1 -> v2
> Suggested-by: SeanChristopherson <seanjc@...gle.com>
> 
> Change the position of handle and asid.
> Change the explain about this patch.
> Dropping the comment about asid + handle.
>  arch/x86/kvm/svm/sev.c | 19 ++++++-------------
>  1 file changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 28064060413a..4448f2e512b9 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -276,31 +276,24 @@ static int sev_guest_init(struct kvm *kvm, struct kvm_sev_cmd *argp)
>  
>  static int sev_bind_asid(struct kvm *kvm, unsigned int handle, int *error)
>  {
> -	struct sev_data_activate activate;
> -	int asid = sev_get_asid(kvm);
> -	int ret;
> -
> -	/* activate ASID on the given handle */
> -	activate.handle = handle;
> -	activate.asid   = asid;
> -	ret = sev_guest_activate(&activate, error);
> +	struct sev_data_activate activate = {
> +		.handle = handle,
> +		.asid = sev_get_asid(kvm),
> +	};
>  
> -	return ret;
> +	return sev_guest_activate(&activate, error);
>  }
>  
>  static int __sev_issue_cmd(int fd, int id, void *data, int *error)
>  {
>  	struct fd f;
> -	int ret;
>  
>  	f = fdget(fd);
>  	if (!f.file)
>  		return -EBADF;
>  
> -	ret = sev_issue_cmd_external_user(f.file, id, data, error);
> -
>  	fdput(f);
> -	return ret;
> +	return sev_issue_cmd_external_user(f.file, id, data, error);

Again, this is broken, the fdput() needs to stay after f.file is consumed, i.e.
eliminating "ret" is wrong.

>  }
>  
>  static int sev_issue_cmd(struct kvm *kvm, int id, void *data, int *error)
> -- 
> 2.25.1