On Mon, 2013-08-05 at 09:27 -0500, Bhushan Bharat-R65777 wrote: > > > -----Original Message----- > > From: Benjamin Herrenschmidt [mailto:benh@xxxxxxxxxxxxxxxxxxx] > > Sent: Saturday, August 03, 2013 9:54 AM > > To: Bhushan Bharat-R65777 > > Cc: Wood Scott-B07421; agraf@xxxxxxx; kvm-ppc@xxxxxxxxxxxxxxx; > > kvm@xxxxxxxxxxxxxxx; linuxppc-dev@xxxxxxxxxxxxxxxx > > Subject: Re: [PATCH 5/6 v2] kvm: powerpc: booke: Add linux pte lookup like > > booke3s > > > > On Sat, 2013-08-03 at 02:58 +0000, Bhushan Bharat-R65777 wrote: > > > One of the problem I saw was that if I put this code in > > > asm/pgtable-32.h and asm/pgtable-64.h then pte_persent() and other > > > friend function (on which this code depends) are defined in pgtable.h. > > > And pgtable.h includes asm/pgtable-32.h and asm/pgtable-64.h before it > > > defines pte_present() and friends functions. > > > > > > Ok I move wove this in asm/pgtable*.h, initially I fought with myself > > > to take this code in pgtable* but finally end up doing here (got > > > biased by book3s :)). > > > > Is there a reason why these routines can not be completely generic in pgtable.h > > ? > > How about the generic function: > > diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h > index d257d98..21daf28 100644 > --- a/arch/powerpc/include/asm/pgtable-ppc64.h > +++ b/arch/powerpc/include/asm/pgtable-ppc64.h > @@ -221,6 +221,27 @@ static inline unsigned long pte_update(struct mm_struct *mm, > return old; > } > > +static inline unsigned long pte_read(pte_t *p) > +{ > +#ifdef PTE_ATOMIC_UPDATES > + pte_t pte; > + pte_t tmp; > + __asm__ __volatile__ ( > + "1: ldarx %0,0,%3\n" > + " andi. %1,%0,%4\n" > + " bne- 1b\n" > + " ori %1,%0,%4\n" > + " stdcx. %1,0,%3\n" > + " bne- 1b" > + : "=&r" (pte), "=&r" (tmp), "=m" (*p) > + : "r" (p), "i" (_PAGE_BUSY) > + : "cc"); > + > + return pte; > +#else > + return pte_val(*p); > +#endif > +#endif > +} > static inline int __ptep_test_and_clear_young(struct mm_struct *mm, > unsigned long addr, pte_t *ptep) Please leave a blank line between functions. > { > diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h > index 690c8c2..dad712c 100644 > --- a/arch/powerpc/include/asm/pgtable.h > +++ b/arch/powerpc/include/asm/pgtable.h > @@ -254,6 +254,45 @@ static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, > } > #endif /* !CONFIG_HUGETLB_PAGE */ > > +static inline pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva, > + int writing, unsigned long *pte_sizep) The name implies that it just reads the PTE. Setting accessed/dirty shouldn't be an undocumented side-effect. Why can't the caller do that (or a different function that the caller calls afterward if desired)? Though even then you have the undocumented side effect of locking the PTE on certain targets. > +{ > + pte_t *ptep; > + pte_t pte; > + unsigned long ps = *pte_sizep; > + unsigned int shift; > + > + ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift); > + if (!ptep) > + return __pte(0); > + if (shift) > + *pte_sizep = 1ul << shift; > + else > + *pte_sizep = PAGE_SIZE; > + > + if (ps > *pte_sizep) > + return __pte(0); > + > + if (!pte_present(*ptep)) > + return __pte(0); > + > +#ifdef CONFIG_PPC64 > + /* Lock PTE (set _PAGE_BUSY) and read */ > + pte = pte_read(ptep); > +#else > + pte = pte_val(*ptep); > +#endif What about 32-bit platforms that need atomic PTEs? -Scott -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
