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From:   "Li, Xin3" <xin3.li@intel.com>
To:     Thomas Gleixner <tglx@linutronix.de>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "x86@kernel.org" <x86@kernel.org>
CC:     "mingo@redhat.com" <mingo@redhat.com>,
        "bp@alien8.de" <bp@alien8.de>,
        "dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
        "hpa@zytor.com" <hpa@zytor.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
        "brgerst@gmail.com" <brgerst@gmail.com>,
        "Bae, Chang Seok" <chang.seok.bae@intel.com>
Subject: RE: [PATCH v3 4/6] x86/gsseg: move local_irq_save/restore() into
 asm_load_gs_index()
Thread-Topic: [PATCH v3 4/6] x86/gsseg: move local_irq_save/restore() into
 asm_load_gs_index()
Thread-Index: AQHY30Hw1PW2GkL5M0i2Gd7SJLBFf64PKDsAgAVE4dA=
Date:   Tue, 18 Oct 2022 17:25:31 +0000
Message-ID: <BN6PR1101MB2161B983B1A85CE3803A3EF8A8289@BN6PR1101MB2161.namprd11.prod.outlook.com>
References: <20221013200134.1487-1-xin3.li@intel.com>
 <20221013200134.1487-5-xin3.li@intel.com> <8735bpbhat.ffs@tglx>
In-Reply-To: <8735bpbhat.ffs@tglx>
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> >  static inline void native_load_gs_index(unsigned int selector)  {
> > -	unsigned long flags;
> > -
> > -	local_irq_save(flags);
> >  	asm_load_gs_index(selector);
> > -	local_irq_restore(flags);
> >  }
>=20
> static inline void native_load_gs_index(unsigned int selector) {
> 	unsigned long flags;
>=20
>         if (cpu_feature_enabled(LKGS)) {
>               native_lkgs(selector);
>         } else {
> 	      local_irq_save(flags);
>               asm_load_gs_index(selector);
> 	      local_irq_restore(flags);
>        }
> }
>=20
> For paravirt enabled kernels we want during feature detection:
>=20
>         if (cpu_feature_enabled(LKGS)))
>         	pv_ops.cpu.load_gs_index =3D native_lkgs;

If we use static_cpu_has in native_load_gs_index
       if (static_cpu_has(X86_FEATURE_LKGS)) {
               native_lkgs(selector);
       }

We don't have to change pv_ops.cpu.load_gs_index, right?

Thanks!
Xin

>=20
> No?
>=20
> Thanks,
>=20
>         tglx