linux-kernel - Re: [PATCHv5 11/19] x86/mm: Implement vma

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Message-ID: <20180723094746.447v2jnegqlosi2f@kshutemo-mobl1>
Date:   Mon, 23 Jul 2018 12:47:46 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Kai Huang <kai.huang@...ux.intel.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCHv5 11/19] x86/mm: Implement vma_keyid()

On Wed, Jul 18, 2018 at 04:40:14PM -0700, Dave Hansen wrote:
> > --- a/arch/x86/mm/mktme.c
> > +++ b/arch/x86/mm/mktme.c
> > @@ -1,3 +1,4 @@
> > +#include <linux/mm.h>
> >  #include <asm/mktme.h>
> >  
> >  phys_addr_t mktme_keyid_mask;
> > @@ -37,3 +38,14 @@ struct page_ext_operations page_mktme_ops = {
> >  	.need = need_page_mktme,
> >  	.init = init_page_mktme,
> >  };
> > +
> > +int vma_keyid(struct vm_area_struct *vma)
> > +{
> > +	pgprotval_t prot;
> > +
> > +	if (!mktme_enabled())
> > +		return 0;
> > +
> > +	prot = pgprot_val(vma->vm_page_prot);
> > +	return (prot & mktme_keyid_mask) >> mktme_keyid_shift;
> > +}
> 
> I'm a bit surprised this isn't inlined.  Not that function calls are
> expensive, but we *could* entirely avoid them using the normal pattern of:
> 
> // In the header:
> static inline vma_keyid(...)
> {
> 	if (!mktme_enabled())
> 		return 0;
> 
> 	return __vma_keyid(...); // <- the .c file version
> }

Okay. I'll do this. But it would be a macros. <asm/mktme.h> gets included
very early. We cannot really use jump label code there directly.

-- 
 Kirill A. Shutemov