On 04.10.2013, at 16:55, Bharat Bhushan wrote:
> lookup_linux_pte() was searching for a pte and also sets access
> flags is writable. This function now searches only pte while
> access flag setting is done explicitly.
>
> This pte lookup is not kvm specific, so moved to common code (asm/pgtable.h)
> My Followup patch will use this on booke.
>
> Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
Paul, please ack.
Alex
> ---
> v5->v6
> - return NULL rather than _pte(0) as this was
> giving compilation error with STRICT_MM_TYPECHECKS
> - Also not only check for NULL pointer in caller rather than
> calling pte_present() twice
>
> arch/powerpc/include/asm/pgtable.h | 24 +++++++++++++++++++++++
> arch/powerpc/kvm/book3s_hv_rm_mmu.c | 36 +++++++++++-----------------------
> 2 files changed, 36 insertions(+), 24 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 7d6eacf..5e41a31 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -223,6 +223,30 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
> #endif
> pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea,
> unsigned *shift);
> +
> +static inline pte_t *lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
> + unsigned long *pte_sizep)
> +{
> + pte_t *ptep;
> + unsigned long ps = *pte_sizep;
> + unsigned int shift;
> +
> + ptep = find_linux_pte_or_hugepte(pgdir, hva, &shift);
> + if (!ptep)
> + return NULL;
> + if (shift)
> + *pte_sizep = 1ul << shift;
> + else
> + *pte_sizep = PAGE_SIZE;
> +
> + if (ps > *pte_sizep)
> + return NULL;
> +
> + if (!pte_present(*ptep))
> + return NULL;
> +
> + return ptep;
> +}
> #endif /* __ASSEMBLY__ */
>
> #endif /* __KERNEL__ */
> diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> index 45e30d6..8ab54e8 100644
> --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c
> @@ -134,25 +134,6 @@ static void remove_revmap_chain(struct kvm *kvm, long pte_index,
> unlock_rmap(rmap);
> }
>
> -static pte_t lookup_linux_pte(pgd_t *pgdir, unsigned long hva,
> - int writing, unsigned long *pte_sizep)
> -{
> - pte_t *ptep;
> - unsigned long ps = *pte_sizep;
> - unsigned int hugepage_shift;
> -
> - ptep = find_linux_pte_or_hugepte(pgdir, hva, &hugepage_shift);
> - if (!ptep)
> - return __pte(0);
> - if (hugepage_shift)
> - *pte_sizep = 1ul << hugepage_shift;
> - else
> - *pte_sizep = PAGE_SIZE;
> - if (ps > *pte_sizep)
> - return __pte(0);
> - return kvmppc_read_update_linux_pte(ptep, writing, hugepage_shift);
> -}
> -
> static inline void unlock_hpte(unsigned long *hpte, unsigned long hpte_v)
> {
> asm volatile(PPC_RELEASE_BARRIER "" : : : "memory");
> @@ -173,6 +154,7 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
> unsigned long is_io;
> unsigned long *rmap;
> pte_t pte;
> + pte_t *ptep;
> unsigned int writing;
> unsigned long mmu_seq;
> unsigned long rcbits;
> @@ -231,8 +213,9 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags,
>
> /* Look up the Linux PTE for the backing page */
> pte_size = psize;
> - pte = lookup_linux_pte(pgdir, hva, writing, &pte_size);
> - if (pte_present(pte)) {
> + ptep = lookup_linux_pte(pgdir, hva, &pte_size);
> + if (ptep) {
> + pte = kvmppc_read_update_linux_pte(ptep, writing);
> if (writing && !pte_write(pte))
> /* make the actual HPTE be read-only */
> ptel = hpte_make_readonly(ptel);
> @@ -661,15 +644,20 @@ long kvmppc_h_protect(struct kvm_vcpu *vcpu, unsigned long flags,
> struct kvm_memory_slot *memslot;
> pgd_t *pgdir = vcpu->arch.pgdir;
> pte_t pte;
> + pte_t *ptep;
>
> psize = hpte_page_size(v, r);
> gfn = ((r & HPTE_R_RPN) & ~(psize - 1)) >> PAGE_SHIFT;
> memslot = __gfn_to_memslot(kvm_memslots(kvm), gfn);
> if (memslot) {
> hva = __gfn_to_hva_memslot(memslot, gfn);
> - pte = lookup_linux_pte(pgdir, hva, 1, &psize);
> - if (pte_present(pte) && !pte_write(pte))
> - r = hpte_make_readonly(r);
> + ptep = lookup_linux_pte(pgdir, hva, &psize);
> + if (ptep) {
> + pte = kvmppc_read_update_linux_pte(ptep,
> + 1);
> + if (pte_present(pte) && !pte_write(pte))
> + r = hpte_make_readonly(r);
> + }
> }
> }
> }
> --
> 1.7.0.4
>
>
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