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iommu/tegra: gart: Add debugging facility 

Page mapping could overwritten by an accident (a bug). We can catch this
case by checking 'VALID' bit of GART's page entry prior to mapping of a
page. Since that check introduces a small performance impact, it should be
enabled explicitly using new GART's kernel module 'debug' parameter.

Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Dmitry Osipenko 2018-04-09 23:07:19 +03:00 committed by Joerg Roedel
parent 6da6c0db53
commit 40c9b882fa
1 changed files with 13 additions and 0 deletions
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13
drivers/iommu/tegra-gart.c
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@ -72,6 +72,8 @@ struct gart_domain {
static struct gart_device *gart_handle; /* unique for a system */
static bool gart_debug;
#define GART_PTE(_pfn) \
(GART_ENTRY_PHYS_ADDR_VALID | ((_pfn) << PAGE_SHIFT))
@ -271,6 +273,7 @@ static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova,
struct gart_device *gart = gart_domain->gart;
unsigned long flags;
unsigned long pfn;
unsigned long pte;
if (!gart_iova_range_valid(gart, iova, bytes))
return -EINVAL;
@ -282,6 +285,14 @@ static int gart_iommu_map(struct iommu_domain *domain, unsigned long iova,
spin_unlock_irqrestore(&gart->pte_lock, flags);
return -EINVAL;
}
if (gart_debug) {
pte = gart_read_pte(gart, iova);
if (pte & GART_ENTRY_PHYS_ADDR_VALID) {
spin_unlock_irqrestore(&gart->pte_lock, flags);
dev_err(gart->dev, "Page entry is in-use\n");
return -EBUSY;
}
}
gart_set_pte(gart, iova, GART_PTE(pfn));
FLUSH_GART_REGS(gart);
spin_unlock_irqrestore(&gart->pte_lock, flags);
@ -515,7 +526,9 @@ static void __exit tegra_gart_exit(void)
subsys_initcall(tegra_gart_init);
module_exit(tegra_gart_exit);
module_param(gart_debug, bool, 0644);
MODULE_PARM_DESC(gart_debug, "Enable GART debugging");
MODULE_DESCRIPTION("IOMMU API for GART in Tegra20");
MODULE_AUTHOR("Hiroshi DOYU <hdoyu@nvidia.com>");
MODULE_ALIAS("platform:tegra-gart");