[RFC 6/7] iommu/core: add fault reporting
From: Ohad Ben-Cohen
Date: Fri Sep 02 2011 - 13:33:26 EST
Add iommu fault report mechanism to the IOMMU API, so implementations
could report about mmu faults (translation errors, hardware errors,
etc..).
Fault reports can be used in several ways:
- mere logging
- reset the device that accessed the faulting address (may be necessary
in case the device is a remote processor for example)
- implement dynamic PTE/TLB loading
Currently the fault handler is installed when allocating a new domain
(less churn for users). Alternatively, we can also add a dedicated
iommu_set_fault_handler() API (presumably with notifiers).
Adopt OMAP's iommu driver (and remove its now-redundant
omap_iommu_set_isr API) and fix existing users of iommu_domain_alloc()
to pass NULL fault handlers.
OMAP's iommu driver will currently only pass the generic IOMMU_ERROR
fault, but in principle we can support dynamic PTE/TLB loading too
in the future.
Signed-off-by: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
---
arch/arm/plat-omap/include/plat/iommu.h | 3 +-
drivers/iommu/iommu.c | 10 +++++-
drivers/iommu/omap-iommu.c | 31 ++--------------
drivers/media/video/omap3isp/isp.c | 2 +-
include/linux/iommu.h | 60 ++++++++++++++++++++++++++++++-
virt/kvm/iommu.c | 2 +-
6 files changed, 74 insertions(+), 34 deletions(-)
diff --git a/arch/arm/plat-omap/include/plat/iommu.h b/arch/arm/plat-omap/include/plat/iommu.h
index 7f1df0e..a1d79ee 100644
--- a/arch/arm/plat-omap/include/plat/iommu.h
+++ b/arch/arm/plat-omap/include/plat/iommu.h
@@ -32,6 +32,7 @@ struct omap_iommu {
void __iomem *regbase;
struct device *dev;
void *isr_priv;
+ struct iommu_domain *domain;
unsigned int refcount;
spinlock_t iommu_lock; /* global for this whole object */
@@ -48,8 +49,6 @@ struct omap_iommu {
struct list_head mmap;
struct mutex mmap_lock; /* protect mmap */
- int (*isr)(struct omap_iommu *obj, u32 da, u32 iommu_errs, void *priv);
-
void *ctx; /* iommu context: registres saved area */
u32 da_start;
u32 da_end;
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index e61a9ba..c08f1a0 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -40,7 +40,13 @@ bool iommu_found(void)
}
EXPORT_SYMBOL_GPL(iommu_found);
-struct iommu_domain *iommu_domain_alloc(void)
+/**
+ * iommu_domain_alloc() - allocate and initialize a new iommu domain
+ * @handler: an optional pointer to a fault handler, or NULL if not needed
+ *
+ * Returns the new domain, or NULL on error.
+ */
+struct iommu_domain *iommu_domain_alloc(iommu_fault_handler_t handler)
{
struct iommu_domain *domain;
int ret;
@@ -49,6 +55,8 @@ struct iommu_domain *iommu_domain_alloc(void)
if (!domain)
return NULL;
+ domain->handler = handler;
+
ret = iommu_ops->domain_init(domain);
if (ret)
goto out_free;
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index bd5f606..089fddc 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -775,6 +775,7 @@ static irqreturn_t iommu_fault_handler(int irq, void *data)
u32 da, errs;
u32 *iopgd, *iopte;
struct omap_iommu *obj = data;
+ struct iommu_domain *domain = obj->domain;
if (!obj->refcount)
return IRQ_NONE;
@@ -786,7 +787,7 @@ static irqreturn_t iommu_fault_handler(int irq, void *data)
return IRQ_HANDLED;
/* Fault callback or TLB/PTE Dynamic loading */
- if (obj->isr && !obj->isr(obj, da, errs, obj->isr_priv))
+ if (!report_iommu_fault(domain, obj->dev, da, IOMMU_ERROR))
return IRQ_HANDLED;
iommu_disable(obj);
@@ -904,33 +905,6 @@ static void omap_iommu_detach(struct omap_iommu *obj)
dev_dbg(obj->dev, "%s: %s\n", __func__, obj->name);
}
-int omap_iommu_set_isr(const char *name,
- int (*isr)(struct omap_iommu *obj, u32 da, u32 iommu_errs,
- void *priv),
- void *isr_priv)
-{
- struct device *dev;
- struct omap_iommu *obj;
-
- dev = driver_find_device(&omap_iommu_driver.driver, NULL, (void *)name,
- device_match_by_alias);
- if (!dev)
- return -ENODEV;
-
- obj = to_iommu(dev);
- spin_lock(&obj->iommu_lock);
- if (obj->refcount != 0) {
- spin_unlock(&obj->iommu_lock);
- return -EBUSY;
- }
- obj->isr = isr;
- obj->isr_priv = isr_priv;
- spin_unlock(&obj->iommu_lock);
-
- return 0;
-}
-EXPORT_SYMBOL_GPL(omap_iommu_set_isr);
-
/*
* OMAP Device MMU(IOMMU) detection
*/
@@ -1115,6 +1089,7 @@ omap_iommu_attach_dev(struct iommu_domain *domain, struct device *dev)
}
omap_domain->iommu_dev = oiommu;
+ oiommu->domain = domain;
out:
spin_unlock(&omap_domain->lock);
diff --git a/drivers/media/video/omap3isp/isp.c b/drivers/media/video/omap3isp/isp.c
index a4baa61..5b06769 100644
--- a/drivers/media/video/omap3isp/isp.c
+++ b/drivers/media/video/omap3isp/isp.c
@@ -2141,7 +2141,7 @@ static int isp_probe(struct platform_device *pdev)
/* to be removed once iommu migration is complete */
isp->iommu = to_iommu(isp->iommu_dev);
- isp->domain = iommu_domain_alloc();
+ isp->domain = iommu_domain_alloc(NULL);
if (!isp->domain) {
dev_err(isp->dev, "can't alloc iommu domain\n");
ret = -ENOMEM;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 9940319..3cbea04 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -26,9 +26,27 @@
#define IOMMU_CACHE (4) /* DMA cache coherency */
struct device;
+struct iommu_domain;
+
+/**
+ * enum iommu_fault_types - iommu fault types
+ *
+ * @IOMMU_ERROR: Unrecoverable error
+ * @IOMMU_TLBMISS: TLB miss while the page table walker is disabled
+ * @IOMMU_NOPTE: TLB miss and no PTE for the requested address
+ */
+enum iommu_fault_types {
+ IOMMU_ERROR,
+ IOMMU_TLBMISS,
+ IOMMU_NOPTE,
+};
+
+typedef int (*iommu_fault_handler_t)(struct iommu_domain *,
+ struct device *, unsigned long, int);
struct iommu_domain {
void *priv;
+ iommu_fault_handler_t handler;
};
#define IOMMU_CAP_CACHE_COHERENCY 0x1
@@ -53,7 +71,7 @@ struct iommu_ops {
extern void register_iommu(struct iommu_ops *ops);
extern bool iommu_found(void);
-extern struct iommu_domain *iommu_domain_alloc(void);
+extern struct iommu_domain *iommu_domain_alloc(iommu_fault_handler_t handler);
extern void iommu_domain_free(struct iommu_domain *domain);
extern int iommu_attach_device(struct iommu_domain *domain,
struct device *dev);
@@ -68,6 +86,40 @@ extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain,
extern int iommu_domain_has_cap(struct iommu_domain *domain,
unsigned long cap);
+/**
+ * report_iommu_fault() - report about an IOMMU fault to the IOMMU framework
+ * @domain: the iommu domain where the fault has happened
+ * @dev: the device where the fault has happened
+ * @iova: the faulting address
+ * @event: the mmu fault type
+ *
+ * This function should be called by the low-level IOMMU implementations
+ * whenever IOMMU faults happen, to allow high-level users, that are
+ * interested in such events, to know about them.
+ *
+ * This event may be useful in case the device, generating the fault,
+ * needs to be restarted before it can be used again (e.g. this device
+ * may be a remote processor), or if dynamic TLB/PTE loading is desired.
+ *
+ * Returns 0 on success and an appropriate error code otherwise (if dynamic
+ * PTE/TLB loading will one day be supported, implementations will be able
+ * to tell whether it succeeded or not according to this return value).
+ */
+static inline int report_iommu_fault(struct iommu_domain *domain,
+ struct device *dev, unsigned long iova, int event)
+{
+ int ret = 0;
+
+ /*
+ * if upper layers showed interest and installed a fault handler,
+ * invoke it.
+ */
+ if (domain->handler)
+ ret = domain->handler(domain, dev, iova, event);
+
+ return ret;
+}
+
#else /* CONFIG_IOMMU_API */
static inline void register_iommu(struct iommu_ops *ops)
@@ -123,6 +175,12 @@ static inline int domain_has_cap(struct iommu_domain *domain,
return 0;
}
+static inline int report_iommu_fault(struct iommu_domain *domain,
+ struct device *dev, unsigned long iova, int event)
+{
+ return 0;
+}
+
#endif /* CONFIG_IOMMU_API */
#endif /* __LINUX_IOMMU_H */
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 78c80f6..2fd67e5 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -233,7 +233,7 @@ int kvm_iommu_map_guest(struct kvm *kvm)
return -ENODEV;
}
- kvm->arch.iommu_domain = iommu_domain_alloc();
+ kvm->arch.iommu_domain = iommu_domain_alloc(NULL);
if (!kvm->arch.iommu_domain)
return -ENOMEM;
--
1.7.4.1
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