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iommu/riscv: Disable SADE

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In terms of the iommu subystem the SADE/GADE feature "3.4. IOMMU updating
of PTE accessed (A) and dirty (D) updates" is called dirty tracking.

There is no reason to enable HW support for this, and the HW cost
associated with it, unless dirty tracking is actually enabled through
iommufd. It should be a dynamic feature linked to user request.

Further, without implementing the read dirty ops the whole thing is
pointless.

Do not set DC.tc.SADE just because the HW has support for dirty tracking.

Tested-by: Vincent Chen <vincent.chen@sifive.com>
Acked-by: Paul Walmsley <pjw@kernel.org> # arch/riscv
Reviewed-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Tested-by: Tomasz Jeznach <tjeznach@rivosinc.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
This commit is contained in:
Jason Gunthorpe 2026-02-27 11:25:37 -04:00 committed by Joerg Roedel
parent e71e001271
commit e93e4a6363
1 changed files with 0 additions and 6 deletions
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6
drivers/iommu/riscv/iommu.c
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@ -810,7 +810,6 @@ struct riscv_iommu_domain {
struct list_head bonds;
spinlock_t lock; /* protect bonds list updates. */
int pscid;
bool amo_enabled;
int numa_node;
unsigned int pgd_mode;
unsigned long *pgd_root;
@ -1201,8 +1200,6 @@ static int riscv_iommu_map_pages(struct iommu_domain *iommu_domain,
if (!(prot & IOMMU_WRITE))
pte_prot = _PAGE_BASE | _PAGE_READ;
else if (domain->amo_enabled)
pte_prot = _PAGE_BASE | _PAGE_READ | _PAGE_WRITE;
else
pte_prot = _PAGE_BASE | _PAGE_READ | _PAGE_WRITE | _PAGE_DIRTY;
@ -1387,7 +1384,6 @@ static struct iommu_domain *riscv_iommu_alloc_paging_domain(struct device *dev)
INIT_LIST_HEAD_RCU(&domain->bonds);
spin_lock_init(&domain->lock);
domain->numa_node = dev_to_node(iommu->dev);
domain->amo_enabled = !!(iommu->caps & RISCV_IOMMU_CAPABILITIES_AMO_HWAD);
domain->pgd_mode = pgd_mode;
domain->pgd_root = iommu_alloc_pages_node_sz(domain->numa_node,
GFP_KERNEL_ACCOUNT, SZ_4K);
@ -1512,8 +1508,6 @@ static struct iommu_device *riscv_iommu_probe_device(struct device *dev)
* the device directory. Do not mark the context valid yet.
*/
tc = 0;
if (iommu->caps & RISCV_IOMMU_CAPABILITIES_AMO_HWAD)
tc |= RISCV_IOMMU_DC_TC_SADE;
for (i = 0; i < fwspec->num_ids; i++) {
dc = riscv_iommu_get_dc(iommu, fwspec->ids[i]);
if (!dc) {