Bharat Bhushan <r65777@xxxxxxxxxxxxx> writes:
> We need to search linux "pte" to get "pte" attributes for
> setting TLB in KVM.
> This patch defines a linux_pte_lookup() function for same.
>
> Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx>
> ---
> arch/powerpc/include/asm/pgtable.h | 35 +++++++++++++++++++++++++++++++++++
> 1 files changed, 35 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 7d6eacf..fd26c04 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -223,6 +223,41 @@ 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;
> + 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);
> +
> + /* wait until _PAGE_BUSY is clear */
> + while (1) {
> + pte = pte_val(*ptep);
> + if (unlikely(pte & _PAGE_BUSY)) {
> + cpu_relax();
> + continue;
> + }
What if we find a THP page that is splitting ? Older function returned
__pte(0) in that case.
> + }
> +
> + /* If pte is not present return None */
> + if (unlikely(!(pte & _PAGE_PRESENT)))
> + return __pte(0);
> +
> + return pte;
> +}
> #endif /* __ASSEMBLY__ */
>
> #endif /* __KERNEL__ */
> --
-aneesh
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