linux-kernel - Re: [PATCH] x86/xen: simplify sysenter and syscall setup

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Message-ID: <Y1EzXQP3/Pn3bme+@zn.tnic>
Date:   Thu, 20 Oct 2022 13:39:09 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Juergen Gross <jgross@...e.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, xen-devel@...ts.xenproject.org
Subject: Re: [PATCH] x86/xen: simplify sysenter and syscall setup

On Thu, Oct 20, 2022 at 01:36:19PM +0200, Juergen Gross wrote:
> xen_enable_sysenter() and xen_enable_syscall() can be simplified a lot.
> 
> Signed-off-by: Juergen Gross <jgross@...e.com>
> ---
>  arch/x86/xen/setup.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index cfa99e8f054b..0f33ed6d3a7b 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -910,17 +910,9 @@ static int register_callback(unsigned type, const void *func)
>  
>  void xen_enable_sysenter(void)
>  {
> -	int ret;
> -	unsigned sysenter_feature;
> -
> -	sysenter_feature = X86_FEATURE_SYSENTER32;
> -
> -	if (!boot_cpu_has(sysenter_feature))
> -		return;
> -
> -	ret = register_callback(CALLBACKTYPE_sysenter, xen_entry_SYSENTER_compat);
> -	if(ret != 0)
> -		setup_clear_cpu_cap(sysenter_feature);
> +	if (boot_cpu_has(X86_FEATURE_SYSENTER32) &&

Can you switch that and below to cpu_feature_enabled() while at it, pls?

> +	if (boot_cpu_has(X86_FEATURE_SYSCALL32) &&
	^^^^^^^^^^^^^^^^^^

Thx.

-- 
Regards/Gruss,
    Boris.

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