On 07/10/15 10:03, Anup Patel wrote:
[...]
+static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops,
+ u64 dma_base, u64 size)
+{
+ struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
+
+ /*
+ * Best case: The device is either part of a group which was
+ * already attached to a domain in a previous call, or it's
+ * been put in a default DMA domain by the IOMMU core.
+ */
+ if (!domain) {
+ /*
+ * Urgh. The IOMMU core isn't going to do default domains
+ * for non-PCI devices anyway, until it has some means of
+ * abstracting the entirely implementation-specific
+ * sideband data/SoC topology/unicorn dust that may or
+ * may not differentiate upstream masters.
+ * So until then, HORRIBLE HACKS!
+ */
+ domain = ops->domain_alloc(IOMMU_DOMAIN_DMA);
+ if (!domain)
+ goto out_no_domain;
+
+ domain->ops = ops;
+ domain->type = IOMMU_DOMAIN_DMA | __IOMMU_DOMAIN_FAKE_DEFAULT;
We require iommu_get_dma_cookie(domain) here. If we dont
allocate iommu cookie then iommu_dma_init_domain() will fail.
The iova cookie is tightly coupled with the domain, so it really only
makes sense for the IOMMU driver to deal with it as part of its
domain_alloc/domain_free callbacks.
Doing that here was one of the nastier 'compatibility' hacks which I've
now taken out; trying to make things work without modifying existing
IOMMU drivers was just too impractical. Drivers which want to play are
now required to support the IOMMU_DOMAIN_DMA type appropriately, but
it's still only a minimal change, as per the example diff for the ARM
SMMU driver below (big pile of further patches necessary to make said
driver compatible in other respects notwithstanding).
Robin.
--->8---
@@ -29,6 +29,7 @@
#define pr_fmt(fmt) "arm-smmu: " fmt
#include <linux/delay.h>
+#include <linux/dma-iommu.h>
#include <linux/dma-mapping.h>
#include <linux/err.h>
#include <linux/interrupt.h>
@@ -973,7 +974,7 @@ static struct iommu_domain
*arm_smmu_domain_alloc(unsigned type)
{
struct arm_smmu_domain *smmu_domain;
- if (type != IOMMU_DOMAIN_UNMANAGED)
+ if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
return NULL;
/*
* Allocate the domain and initialise some of its data structures.
@@ -984,6 +985,12 @@ static struct iommu_domain
*arm_smmu_domain_alloc(unsigned type)
if (!smmu_domain)
return NULL;
+ if (type == IOMMU_DOMAIN_DMA &&
+ iommu_get_dma_cookie(&smmu_domain->domain)) {
+ kfree(smmu_domain);
+ return NULL;
+ }
+
mutex_init(&smmu_domain->init_mutex);
spin_lock_init(&smmu_domain->pgtbl_lock);
@@ -998,6 +1005,7 @@ static void arm_smmu_domain_free(struct
iommu_domain *domain)
* Free the domain resources. We assume that all devices have
* already been detached.
*/
+ iommu_put_dma_cookie(domain);
arm_smmu_destroy_domain_context(domain);
kfree(smmu_domain);
}
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