linux-kernel - Re: [PATCH v2 01/23] x86/fpu: Extend fpu_xstate

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Message-ID: <87zgozax12.ffs@tglx>
Date:   Fri, 17 Dec 2021 19:47:37 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Jing Liu <jing2.liu@...el.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        pbonzini@...hat.com
Cc:     seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
        jing2.liu@...ux.intel.com, jing2.liu@...el.com,
        guang.zeng@...el.com, wei.w.wang@...el.com, yang.zhong@...el.com
Subject: Re: [PATCH v2 01/23] x86/fpu: Extend fpu_xstate_prctl() with guest
 permissions

On Fri, Dec 17 2021 at 19:45, Thomas Gleixner wrote:

> On Fri, Dec 17 2021 at 07:29, Jing Liu wrote:
>>  
>> -static int __xstate_request_perm(u64 permitted, u64 requested)
>> +static int __xstate_request_perm(u64 permitted, u64 requested, bool guest)
>>  {
>>  	/*
>>  	 * This deliberately does not exclude !XSAVES as we still might
>> @@ -1605,6 +1605,7 @@ static int __xstate_request_perm(u64 permitted, u64 requested)
>>  	 */
>>  	bool compacted = cpu_feature_enabled(X86_FEATURE_XSAVES);
>>  	struct fpu *fpu = &current->group_leader->thread.fpu;
>> +	struct fpu_state_perm *perm;
>>  	unsigned int ksize, usize;
>>  	u64 mask;
>>  	int ret;
>
> needs to be
>
>       int ret = 0;
>

Alternatively return 0 at the end of the function.