Thanks for the feedback, Robin, and, Dmitry.
I mostly agree with all your comments, pls see my responses inline.
I'll make these fixes in V2.
On 1/17/19 8:50 AM, Robin Murphy wrote:
> On 17/01/2019 15:13, Dmitry Osipenko wrote:
>> 16.01.2019 23:50, Navneet Kumar пишет:
>>> * Allocate dma iova cookie for a domain while adding dma iommu
>>> devices.
>>> * Perform a stricter check for domain type parameter.
>>>
>>
>> Commit message should tell what exactly is getting "fixed". Apparently you're trying to support T132 ARM64 here.
I'll fix it.
>>
>>> Signed-off-by: Navneet Kumar <navneetk@xxxxxxxxxx>
>>> ---
>>> drivers/iommu/tegra-smmu.c | 43 +++++++++++++++++++++++++++----------------
>>> 1 file changed, 27 insertions(+), 16 deletions(-)
>>>
>>> diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
>>> index 543f7c9..ee4d8a8 100644
>>> --- a/drivers/iommu/tegra-smmu.c
>>> +++ b/drivers/iommu/tegra-smmu.c
>>> @@ -16,6 +16,7 @@
>>> #include <linux/platform_device.h>
>>> #include <linux/slab.h>
>>> #include <linux/dma-mapping.h>
>>> +#include <linux/dma-iommu.h>
>>> #include <soc/tegra/ahb.h>
>>> #include <soc/tegra/mc.h>
>>> @@ -271,8 +272,10 @@ static bool tegra_smmu_capable(enum iommu_cap cap)
>>> static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
>>> {
>>> struct tegra_smmu_as *as;
>>> + int ret;
>>> - if (type != IOMMU_DOMAIN_UNMANAGED)
>>> + if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA &&
>>> + type != IOMMU_DOMAIN_IDENTITY)
>>> return NULL;
>>
>> Should be better to write these lines like this for the sake of readability:
>>
>> if (type != IOMMU_DOMAIN_UNMANAGED &&
>> type != IOMMU_DOMAIN_DMA &&
>> type != IOMMU_DOMAIN_IDENTITY)
>> return NULL;
>
> Furthermore, AFAICS there's no special handling being added for identity domains - don't pretend to support them by giving back a regular translation domain, that's just misleading and broken.
Agreed.
>
>>
>>
>>> as = kzalloc(sizeof(*as), GFP_KERNEL);
>>> @@ -281,26 +284,22 @@ static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
>>> as->attr = SMMU_PD_READABLE | SMMU_PD_WRITABLE | SMMU_PD_NONSECURE;
>>> + ret = (type == IOMMU_DOMAIN_DMA) ? iommu_get_dma_cookie(&as->domain) :
>>> + -ENODEV;
>>
>> This makes to fail allocation of domain that has type other than IOMMU_DOMAIN_DMA.
>>
>> Should be:
>>
>> if (type == IOMMU_DOMAIN_DMA) {
>> err = iommu_get_dma_cookie(&as->domain);
>> if (err)
>> goto free_as;
>> }
>>
Agreed.
>>
>>> + if (ret)
>>> + goto free_as;
>>> +
>>> as->pd = alloc_page(GFP_KERNEL | __GFP_DMA | __GFP_ZERO);
>>> - if (!as->pd) {
>>> - kfree(as);
>>> - return NULL;
>>> - }
>>> + if (!as->pd)
>>> + goto put_dma_cookie;
>>> as->count = kcalloc(SMMU_NUM_PDE, sizeof(u32), GFP_KERNEL);
>>> - if (!as->count) {
>>> - __free_page(as->pd);
>>> - kfree(as);
>>> - return NULL;
>>> - }
>>> + if (!as->count)
>>> + goto free_pd_range;
>>> as->pts = kcalloc(SMMU_NUM_PDE, sizeof(*as->pts), GFP_KERNEL);
>>> - if (!as->pts) {
>>> - kfree(as->count);
>>> - __free_page(as->pd);
>>> - kfree(as);
>>> - return NULL;
>>> - }
>>> + if (!as->pts)
>>> + goto free_pts;
>>> /* setup aperture */
>>> as->domain.geometry.aperture_start = 0;
>>> @@ -308,6 +307,18 @@ static struct iommu_domain *tegra_smmu_domain_alloc(unsigned type)
>>> as->domain.geometry.force_aperture = true;
>>> return &as->domain;
>>> +
>>> +free_pts:
>>> + kfree(as->pts);
>>> +free_pd_range:
>>> + __free_page(as->pd);
>>> +put_dma_cookie:
>>> + if (type == IOMMU_DOMAIN_DMA)
>
> FWIW you don't strictly need that check - since domain->iova_cookie won't be set for other domain types anyway, iommu_put_dma_cookie() will simply ignore them.
>
I'll still keep that check and not rely solely on the put_dma_cookie API to handle this case.
This will keep the code robust even if the put_dma_cookie API changes in future (for whatever reason).
It also looks like the canonical usage in other drivers.
>>> + iommu_put_dma_cookie(&as->domain);
>>> +free_as:
>>> + kfree(as);
>>> +
>>> + return NULL;
>>> }
>>> static void tegra_smmu_domain_free(struct iommu_domain *domain)
>
> How about not leaking the cookie when you free a DMA ops domain?
>
Agreed.
> Robin.
