linux-kernel - Re: [RFC v2 06/12] powerpc: Program HPTE key protection bits.

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Date:   Tue, 20 Jun 2017 16:26:45 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        dave.hansen@...el.com, paulus@...ba.org,
        aneesh.kumar@...ux.vnet.ibm.com
Subject: Re: [RFC v2 06/12] powerpc: Program HPTE key protection bits.

On Tue, Jun 20, 2017 at 01:51:45PM +0530, Anshuman Khandual wrote:
> On 06/17/2017 09:22 AM, Ram Pai wrote:
> > Map the PTE protection key bits to the HPTE key protection bits,
> > while creatiing HPTE  entries.
> > 
> > Signed-off-by: Ram Pai <linuxram@...ibm.com>
> > ---
> >  arch/powerpc/include/asm/book3s/64/mmu-hash.h | 5 +++++
> >  arch/powerpc/include/asm/pkeys.h              | 7 +++++++
> >  arch/powerpc/mm/hash_utils_64.c               | 5 +++++
> >  3 files changed, 17 insertions(+)
> > 
> > diff --git a/arch/powerpc/include/asm/book3s/64/mmu-hash.h b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> > index cfb8169..3d7872c 100644
> > --- a/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> > +++ b/arch/powerpc/include/asm/book3s/64/mmu-hash.h
> > @@ -90,6 +90,8 @@
> >  #define HPTE_R_PP0		ASM_CONST(0x8000000000000000)
> >  #define HPTE_R_TS		ASM_CONST(0x4000000000000000)
> >  #define HPTE_R_KEY_HI		ASM_CONST(0x3000000000000000)
> > +#define HPTE_R_KEY_BIT0		ASM_CONST(0x2000000000000000)
> > +#define HPTE_R_KEY_BIT1		ASM_CONST(0x1000000000000000)
> >  #define HPTE_R_RPN_SHIFT	12
> >  #define HPTE_R_RPN		ASM_CONST(0x0ffffffffffff000)
> >  #define HPTE_R_RPN_3_0		ASM_CONST(0x01fffffffffff000)
> > @@ -104,6 +106,9 @@
> >  #define HPTE_R_C		ASM_CONST(0x0000000000000080)
> >  #define HPTE_R_R		ASM_CONST(0x0000000000000100)
> >  #define HPTE_R_KEY_LO		ASM_CONST(0x0000000000000e00)
> > +#define HPTE_R_KEY_BIT2		ASM_CONST(0x0000000000000800)
> > +#define HPTE_R_KEY_BIT3		ASM_CONST(0x0000000000000400)
> > +#define HPTE_R_KEY_BIT4		ASM_CONST(0x0000000000000200)
> > 
> 
> Should we indicate/document how these 5 bits are not contiguous
> in the HPTE format for any given real page ?

I can, but its all well documented in the ISA. Infact all the bits and
the macros are one to one translation from the ISA.

> 
> >  #define HPTE_V_1TB_SEG		ASM_CONST(0x4000000000000000)
> >  #define HPTE_V_VRMA_MASK	ASM_CONST(0x4001ffffff000000)
> > diff --git a/arch/powerpc/include/asm/pkeys.h b/arch/powerpc/include/asm/pkeys.h
> > index 0f3dca8..9b6820d 100644
> > --- a/arch/powerpc/include/asm/pkeys.h
> > +++ b/arch/powerpc/include/asm/pkeys.h
> > @@ -27,6 +27,13 @@
> >  		((vm_flags & VM_PKEY_BIT3) ? H_PAGE_PKEY_BIT1 : 0x0UL) |     \
> >  		((vm_flags & VM_PKEY_BIT4) ? H_PAGE_PKEY_BIT0 : 0x0UL))
> > 
> > +#define calc_pte_to_hpte_pkey_bits(pteflags)	\
> > +	(((pteflags & H_PAGE_PKEY_BIT0) ? HPTE_R_KEY_BIT0 : 0x0UL) |	\
> > +	((pteflags & H_PAGE_PKEY_BIT1) ? HPTE_R_KEY_BIT1 : 0x0UL) |	\
> > +	((pteflags & H_PAGE_PKEY_BIT2) ? HPTE_R_KEY_BIT2 : 0x0UL) |	\
> > +	((pteflags & H_PAGE_PKEY_BIT3) ? HPTE_R_KEY_BIT3 : 0x0UL) |	\
> > +	((pteflags & H_PAGE_PKEY_BIT4) ? HPTE_R_KEY_BIT4 : 0x0UL))
> > +
> 
> We can drop calc_ in here. pte_to_hpte_pkey_bits should be
> sufficient.

ok. will do.

thanks for your comments,
RP