Re: [RFC PATCH v1] iommu/io-pgtable-arm: Check for leaf entry right after finding it

[Will Deacon]

On Mon, Feb 13, 2017 at 01:50:29PM +0200, Oleksandr Tyshchenko wrote:
> On Mon, Feb 13, 2017 at 1:27 PM, Will Deacon  wrote:
> > On Mon, Feb 13, 2017 at 01:07:02PM +0200, Oleksandr Tyshchenko wrote:
> >> Any comments?
> >
> > Looks fine to me, but I don't think it's urgent and I already sent my
> > SMMU pull for 4.11. I'll send this as a fix after the merge window.
> OK. Thank you.
> 
> >
> > I suspect we need something similar for io-pgtable-arm-v7s.c, too.
> Agree. On the whole I will be able to make similar patch for arm-v7s,
> but I won't be 100% sure
> since I don't have any boards where arm-v7s compatible IOMMU installed.
> 
> Shall I make patch for arm-v7s too?

Yes, please. Robin seems to enjoy using short-descriptor, so he might
give it a spin for you if you ask nicely.

Will
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [RFC PATCH v1] iommu/io-pgtable-arm: Check for leaf entry right after finding it

[Oleksandr Tyshchenko]

On Mon, Feb 13, 2017 at 1:27 PM, Will Deacon  wrote:
> On Mon, Feb 13, 2017 at 01:07:02PM +0200, Oleksandr Tyshchenko wrote:
>> Any comments?
>
> Looks fine to me, but I don't think it's urgent and I already sent my
> SMMU pull for 4.11. I'll send this as a fix after the merge window.
OK. Thank you.

>
> I suspect we need something similar for io-pgtable-arm-v7s.c, too.
Agree. On the whole I will be able to make similar patch for arm-v7s,
but I won't be 100% sure
since I don't have any boards where arm-v7s compatible IOMMU installed.

Shall I make patch for arm-v7s too?

>
> Will



-- 
Regards,

Oleksandr Tyshchenko
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [RFC PATCH v1] iommu/io-pgtable-arm: Check for leaf entry right after finding it

[Will Deacon]

On Mon, Feb 13, 2017 at 01:07:02PM +0200, Oleksandr Tyshchenko wrote:
> Any comments?

Looks fine to me, but I don't think it's urgent and I already sent my
SMMU pull for 4.11. I'll send this as a fix after the merge window.

I suspect we need something similar for io-pgtable-arm-v7s.c, too.

Will
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

Re: [RFC PATCH v1] iommu/io-pgtable-arm: Check for leaf entry right after finding it

[Oleksandr Tyshchenko]

Hi, all.

Any comments?

On Thu, Feb 9, 2017 at 3:56 PM, Oleksandr Tyshchenko
 wrote:
> From: Oleksandr Tyshchenko 
>
> Do a check for already installed leaf entry at the current level before
> performing any actions when trying to map.
>
> This check is already present in arm_lpae_init_pte(), i.e. before
> installing new leaf entry at the current level if conditions to do so
> are met (size == block_size).
>
> But, this might be insufficient in case when we have already
> installed block mapping at this level and it is not time to
> install new leaf entry (size != block_size).
> In that case we continue walking the page table down with wrong pointer
> to the next level.
>
> So, move check from arm_lpae_init_pte() to __arm_lpae_map() in order to
> avoid all cases.
>
> Signed-off-by: Oleksandr Tyshchenko 
> ---
> I hope that following actions can help to catch it:
> 1. Call iommu_map for a block mapping (e.g. 2M) at some address
>(e.g. iova 0x8000 pa 0x8000).
> 2. Call iommu_map for a page mapping (4k) at some address from
>the previous mapped region (e.g. iova 0x80008000 pa 0x9000).
>
> I understand that after iommu_map should be iommu_unmap, but
> different scenarios may occur).
> ---
> ---
>  drivers/iommu/io-pgtable-arm.c | 13 -
>  1 file changed, 8 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
> index f5c90e1..ebdb82f 100644
> --- a/drivers/iommu/io-pgtable-arm.c
> +++ b/drivers/iommu/io-pgtable-arm.c
> @@ -272,11 +272,7 @@ static int arm_lpae_init_pte(struct arm_lpae_io_pgtable 
> *data,
> arm_lpae_iopte pte = prot;
> struct io_pgtable_cfg *cfg = >iop.cfg;
>
> -   if (iopte_leaf(*ptep, lvl)) {
> -   /* We require an unmap first */
> -   WARN_ON(!selftest_running);
> -   return -EEXIST;
> -   } else if (iopte_type(*ptep, lvl) == ARM_LPAE_PTE_TYPE_TABLE) {
> +   if (iopte_type(*ptep, lvl) == ARM_LPAE_PTE_TYPE_TABLE) {
> /*
>  * We need to unmap and free the old table before
>  * overwriting it with a block entry.
> @@ -315,6 +311,13 @@ static int __arm_lpae_map(struct arm_lpae_io_pgtable 
> *data, unsigned long iova,
> /* Find our entry at the current level */
> ptep += ARM_LPAE_LVL_IDX(iova, lvl, data);
>
> +   /* Check for already installed leaf entry */
> +   if (iopte_leaf(*ptep, lvl)) {
> +   /* We require an unmap first */
> +   WARN_ON(!selftest_running);
> +   return -EEXIST;
> +   }
> +
> /* If we can install a leaf entry at this level, then do so */
> if (size == block_size && (size & cfg->pgsize_bitmap))
> return arm_lpae_init_pte(data, iova, paddr, prot, lvl, ptep);
> --
> 2.7.4
>



-- 
Regards,

Oleksandr Tyshchenko
___
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu