Re: [PATCH V10 04/11] iommu/vt-d: Use helper function to skip agaw for SL

Lu Baolu
2020-03-29T07:35:57Z

On 2020/3/28 0:05, Auger Eric wrote:
> Hi Jacob,
>
> On 3/27/20 12:55 PM, Tian, Kevin wrote:
>>> From: Jacob Pan<jacob.jun.pan@linux.intel.com>
>>> Sent: Saturday, March 21, 2020 7:28 AM
>>>
>>> Signed-off-by: Jacob Pan<jacob.jun.pan@linux.intel.com>
>>> ---
>>> drivers/iommu/intel-pasid.c | 14 ++++----------
>>> 1 file changed, 4 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
>>> index 191508c7c03e..9bdb7ee228b6 100644
>>> --- a/drivers/iommu/intel-pasid.c
>>> +++ b/drivers/iommu/intel-pasid.c
>>> @@ -544,17 +544,11 @@ int intel_pasid_setup_second_level(struct
>>> intel_iommu *iommu,
>>> return -EINVAL;
>>> }
>>>
>>> - /*
>>> - * Skip top levels of page tables for iommu which has less agaw
>>> - * than default. Unnecessary for PT mode.
>>> - */
>>> pgd = domain->pgd;
>>> - for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
>>> - pgd = phys_to_virt(dma_pte_addr(pgd));
>>> - if (!dma_pte_present(pgd)) {
>>> - dev_err(dev, "Invalid domain page table\n");
>>> - return -EINVAL;
>>> - }
>>> + agaw = iommu_skip_agaw(domain, iommu, &pgd);
>>> + if (agaw < 0) {
>>> + dev_err(dev, "Invalid domain page table\n");
> is the dev_err() really requested. I see in domain_setup_first_level(),
> there is none.
>>> + return -EINVAL;
>>> }
>> ok, I see how it is used. possibly combine last and this one together since
>> it's mostly moving code...
> I tend to agree with Kevin. May be better squash the 2 patches. Also not
> sure the inline of iommu_skip_agaw() is meaningful then. Also Add commit
> messages on the resulting patch.
>
> Note domain_setup_first_level() also could use the helper while we are
> it (if declaration moved to common helper). Only the error code differs
> in case !dma_pte_present(pgd), ie. -ENOMEM. May be good to align.
>
> Otherwise those stuff may be done in a fixup patch.

Agreed. Will squash these 2 patches with a meaningful commit message. As
for using this helper in other files, like domain_setup_first_level(),
we need more review and test efforts, hence it's better to put it in a
followup patch.

Best regards,
baolu