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

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Message-ID: <87deb6d1-b2e3-2560-4b49-d50819d3c4a7@suse.com>
Date:   Thu, 20 Oct 2022 13:41:42 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Borislav Petkov <bp@...en8.de>
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 20.10.22 13:39, Borislav Petkov wrote:
> 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) &&
> 	^^^^^^^^^^^^^^^^^^

Yes, of course.


Juergen

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