It was never entirely clear whether the force_aperture flag was supposed
to be a hardware capability or a software policy. So far things seem to
have leant towards the latter, given that the only drivers not setting
the flag are ones where the aperture is seemingly a whole virtual
address space such that accesses outside it wouldn't be possible, and
the one driver which definitely can't enforce it in hardware *does*
still set the flag.
On reflection, though, it makes little sense for drivers to dictate
usage policy to callers, and the interpretation that a driver setting
the flag might also translate addresses outside the given aperture but
has for some reason chosen not to is not actually a useful one. It seems
a lot more logical to treat the aperture as the absolute limit of what
can be translated, and the flag to indicate what would happen if a
device did try to access an address outside the aperture, i.e. whether
the access would fault or pass through untranslated. As such, reframe
the flag consistent with a hardware capability in the hope of clearing
up the misconception.
Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
---
drivers/iommu/dma-iommu.c | 19 +++++++------------
drivers/iommu/mtk_iommu_v1.c | 4 ++++
drivers/iommu/sprd-iommu.c | 1 +
drivers/iommu/tegra-gart.c | 2 +-
4 files changed, 13 insertions(+), 13 deletions(-)
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 7a9f0b0bddbd..4693b021d54f 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -548,24 +548,19 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
if (!cookie || cookie->type != IOMMU_DMA_IOVA_COOKIE)
return -EINVAL;
+ /*
+ * If the IOMMU only offers a non-isolated GART-style translation
+ * aperture, just let the device use dma-direct.
+ */
+ if (!domain->geometry.force_aperture)
+ return -EINVAL;
+
iovad = &cookie->iovad;
/* Use the smallest supported page size for IOVA granularity */
order = __ffs(domain->pgsize_bitmap);
base_pfn = max_t(unsigned long, 1, base >> order);
- /* Check the domain allows at least some access to the device... */
- if (domain->geometry.force_aperture) {
- if (base > domain->geometry.aperture_end ||
- limit < domain->geometry.aperture_start) {
- pr_warn("specified DMA range outside IOMMU capability\n");
- return -EFAULT;
- }
- /* ...then finally give it a kicking to make sure it fits */
- base_pfn = max_t(unsigned long, base_pfn,
- domain->geometry.aperture_start >> order);
- }
-
/* start_pfn is always nonzero for an already-initialised domain */
mutex_lock(&cookie->mutex);
if (iovad->start_pfn) {
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 8a0a5e5d049f..3ca813919974 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -281,6 +281,10 @@ static struct iommu_domain *mtk_iommu_v1_domain_alloc(unsigned type)
if (!dom)
return NULL;
+ dom->domain.geometry.aperture_start = 0;
+ dom->domain.geometry.aperture_end = SZ_4G - 1;
+ dom->domain.geometry.force_aperture = true;
+
return &dom->domain;
}
diff --git a/drivers/iommu/sprd-iommu.c b/drivers/iommu/sprd-iommu.c
index 39e34fdeccda..eb684d8807ca 100644
--- a/drivers/iommu/sprd-iommu.c
+++ b/drivers/iommu/sprd-iommu.c
@@ -148,6 +148,7 @@ static struct iommu_domain *sprd_iommu_domain_alloc(unsigned int domain_type)
dom->domain.geometry.aperture_start = 0;
dom->domain.geometry.aperture_end = SZ_256M - 1;
+ dom->domain.geometry.force_aperture = true;
return &dom->domain;
}
diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
index 0a121cbc17b8..c221af290798 100644
--- a/drivers/iommu/tegra-gart.c
+++ b/drivers/iommu/tegra-gart.c
@@ -160,7 +160,7 @@ static struct iommu_domain *gart_iommu_domain_alloc(unsigned type)
domain->domain.geometry.aperture_start = gart->iovmm_base;
domain->domain.geometry.aperture_end = gart->iovmm_end - 1;
- domain->domain.geometry.force_aperture = true;
+ domain->domain.geometry.force_aperture = false;
num_pages = (gart->iovmm_end - gart->iovmm_base) / GART_PAGE_SIZE;
domain->savedata = vcalloc(num_pages, sizeof(u32));
--
2.39.2.101.g768bb238c484.dirty
