Re: [PATCH 1/6] powerpc/mm: Wire up hpte_removebolted for powernv

[Rashmica Gupta <rashmica.g@gmail.com>]

Looks good to me


On 23/05/17 14:05, Oliver O'Halloran wrote:
> From: Anton Blanchard <anton@samba.org>
>
> Adds support for removing bolted (i.e kernel linear mapping) mappings on
> powernv. This is needed to support memory hot unplug operations which
> are required for the teardown of DAX/PMEM devices.
>
> Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com>
^^ x2
> Signed-off-by: Anton Blanchard <anton@samba.org>
> Signed-off-by: Oliver O'Halloran <oohall@gmail.com>
> ---
> v1 -> v2: Fixed the commit author
>            Added VM_WARN_ON() if we attempt to remove an unbolted hpte
> ---
>   arch/powerpc/mm/hash_native_64.c | 33 +++++++++++++++++++++++++++++++++
>   1 file changed, 33 insertions(+)
>
> diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
> index 65bb8f33b399..b534d041cfe8 100644
> --- a/arch/powerpc/mm/hash_native_64.c
> +++ b/arch/powerpc/mm/hash_native_64.c
> @@ -407,6 +407,38 @@ static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea,
>   	tlbie(vpn, psize, psize, ssize, 0);
>   }
>   
> +/*
> + * Remove a bolted kernel entry. Memory hotplug uses this.
> + *
> + * No need to lock here because we should be the only user.
> + */
> +static int native_hpte_removebolted(unsigned long ea, int psize, int ssize)
> +{
> +	unsigned long vpn;
> +	unsigned long vsid;
> +	long slot;
> +	struct hash_pte *hptep;
> +
> +	vsid = get_kernel_vsid(ea, ssize);
> +	vpn = hpt_vpn(ea, vsid, ssize);
> +
> +	slot = native_hpte_find(vpn, psize, ssize);
> +	if (slot == -1)
> +		return -ENOENT;
> +
> +	hptep = htab_address + slot;
> +
> +	VM_WARN_ON(!(be64_to_cpu(hptep->v) & HPTE_V_BOLTED));
> +
> +	/* Invalidate the hpte */
> +	hptep->v = 0;
> +
> +	/* Invalidate the TLB */
> +	tlbie(vpn, psize, psize, ssize, 0);
> +	return 0;
> +}
> +
> +
>   static void native_hpte_invalidate(unsigned long slot, unsigned long vpn,
>   				   int bpsize, int apsize, int ssize, int local)
>   {
> @@ -725,6 +757,7 @@ void __init hpte_init_native(void)
>   	mmu_hash_ops.hpte_invalidate	= native_hpte_invalidate;
>   	mmu_hash_ops.hpte_updatepp	= native_hpte_updatepp;
>   	mmu_hash_ops.hpte_updateboltedpp = native_hpte_updateboltedpp;
> +	mmu_hash_ops.hpte_removebolted = native_hpte_removebolted;
>   	mmu_hash_ops.hpte_insert	= native_hpte_insert;
>   	mmu_hash_ops.hpte_remove	= native_hpte_remove;
>   	mmu_hash_ops.hpte_clear_all	= native_hpte_clear;