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Date: Wed, 25 May 2022 21:11:20 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jean-Philippe Brucker <jean-philippe@...aro.org>,
Robin Murphy <robin.murphy@....com>
Cc: baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
Jason Gunthorpe <jgg@...dia.com>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>, linux-kernel@...r.kernel.org,
iommu@...ts.linux-foundation.org,
Jacob jun Pan <jacob.jun.pan@...el.com>
Subject: Re: [PATCH v7 03/10] iommu/sva: Add iommu_sva_domain support
On 2022/5/25 19:06, Jean-Philippe Brucker wrote:
> On Wed, May 25, 2022 at 11:07:49AM +0100, Robin Murphy wrote:
>>> Did you mean @handler and @handler_token staffs below?
>>>
>>> struct iommu_domain {
>>> unsigned type;
>>> const struct iommu_domain_ops *ops;
>>> unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
>>> iommu_fault_handler_t handler;
>>> void *handler_token;
>>> struct iommu_domain_geometry geometry;
>>> struct iommu_dma_cookie *iova_cookie;
>>> };
>>>
>>> Is it only for DMA domains? From the point view of IOMMU faults, it
>>> seems to be generic.
>> Yes, it's the old common iommu_set_fault_handler() stuff (which arguably is
>> more of a "notifier" than a "handler"), but I assume that that's irrelevant
>> if SVA is using IOPF instead?
> Yes IOMMU drivers call either the newer iommu_report_device_fault() or the
> old report_iommu_fault(), and only the former can support IOPF/SVA. I've
> tried to merge them before but never completed it. I think the main issue
> was with finding the endpoint that caused the fault from the fault
> handler. Some IOMMU drivers just pass the IOMMU device to
> report_iommu_fault(). I'll probably pick that up at some point.
Thank you all for the comments and suggestions. Below is the refreshed
patch. Hope that I didn't miss anything.
From 463c04cada8e8640598f981d8d16157781b9de6f Mon Sep 17 00:00:00 2001
From: Lu Baolu <baolu.lu@...ux.intel.com>
Date: Wed, 11 May 2022 20:59:24 +0800
Subject: [PATCH 04/11] iommu: Add sva iommu_domain support
The sva iommu_domain represents a hardware pagetable that the IOMMU
hardware could use for SVA translation. This adds some infrastructure
to support SVA domain in the iommu common layer. It includes:
- Extend the iommu_domain to support a new IOMMU_DOMAIN_SVA domain
type. The IOMMU drivers that support SVA should provide the sva
domain specific iommu_domain_ops.
- Add a helper to allocate an SVA domain. The iommu_domain_free()
is still used to free an SVA domain.
- Add helpers to attach an SVA domain to a device and the reverse
operation.
Some buses, like PCI, route packets without considering the PASID value.
Thus a DMA target address with PASID might be treated as P2P if the
address falls into the MMIO BAR of other devices in the group. To make
things simple, the attach/detach interfaces only apply to devices
belonging to the singleton groups, and the singleton is immutable in
fabric i.e. not affected by hotplug.
The iommu_attach/detach_device_pasid() can be used for other purposes,
such as kernel DMA with pasid, mediation device, etc.
Suggested-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
Suggested-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
---
drivers/iommu/iommu.c | 93 +++++++++++++++++++++++++++++++++++++++++++
include/linux/iommu.h | 45 ++++++++++++++++++++-
2 files changed, 136 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 63b64b4e8a38..b1a2ad64a413 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -27,6 +27,7 @@
#include <linux/module.h>
#include <linux/cc_platform.h>
#include <trace/events/iommu.h>
+#include <linux/sched/mm.h>
static struct kset *iommu_group_kset;
static DEFINE_IDA(iommu_group_ida);
@@ -39,6 +40,7 @@ struct iommu_group {
struct kobject kobj;
struct kobject *devices_kobj;
struct list_head devices;
+ struct xarray pasid_array;
struct mutex mutex;
void *iommu_data;
void (*iommu_data_release)(void *iommu_data);
@@ -666,6 +668,7 @@ struct iommu_group *iommu_group_alloc(void)
mutex_init(&group->mutex);
INIT_LIST_HEAD(&group->devices);
INIT_LIST_HEAD(&group->entry);
+ xa_init(&group->pasid_array);
ret = ida_simple_get(&iommu_group_ida, 0, 0, GFP_KERNEL);
if (ret < 0) {
@@ -1961,6 +1964,8 @@ EXPORT_SYMBOL_GPL(iommu_domain_alloc);
void iommu_domain_free(struct iommu_domain *domain)
{
+ if (domain->type == IOMMU_DOMAIN_SVA)
+ mmdrop(domain->mm);
iommu_put_dma_cookie(domain);
domain->ops->free(domain);
}
@@ -3277,3 +3282,91 @@ bool iommu_group_dma_owner_claimed(struct
iommu_group *group)
return user;
}
EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
+
+struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
+ struct mm_struct *mm)
+{
+ const struct iommu_ops *ops = dev_iommu_ops(dev);
+ struct iommu_domain *domain;
+
+ domain = ops->domain_alloc(IOMMU_DOMAIN_SVA);
+ if (!domain)
+ return NULL;
+
+ domain->type = IOMMU_DOMAIN_SVA;
+ mmgrab(mm);
+ domain->mm = mm;
+
+ return domain;
+}
+
+static bool iommu_group_immutable_singleton(struct iommu_group *group,
+ struct device *dev)
+{
+ int count;
+
+ mutex_lock(&group->mutex);
+ count = iommu_group_device_count(group);
+ mutex_unlock(&group->mutex);
+
+ if (count != 1)
+ return false;
+
+ /*
+ * The PCI device could be considered to be fully isolated if all
+ * devices on the path from the device to the host-PCI bridge are
+ * protected from peer-to-peer DMA by ACS.
+ */
+ if (dev_is_pci(dev))
+ return pci_acs_path_enabled(to_pci_dev(dev), NULL,
+ REQ_ACS_FLAGS);
+
+ /*
+ * Otherwise, the device came from DT/ACPI, assume it is static and
+ * then singleton can know from the device count in the group.
+ */
+ return true;
+}
+
+int iommu_attach_device_pasid(struct iommu_domain *domain, struct
device *dev,
+ ioasid_t pasid)
+{
+ struct iommu_group *group;
+ int ret = -EBUSY;
+ void *curr;
+
+ if (!domain->ops->set_dev_pasid)
+ return -EOPNOTSUPP;
+
+ group = iommu_group_get(dev);
+ if (!group || !iommu_group_immutable_singleton(group, dev)) {
+ iommu_group_put(group);
+ return -EINVAL;
+ }
+
+ mutex_lock(&group->mutex);
+ curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain, GFP_KERNEL);
+ if (curr)
+ goto out_unlock;
+ ret = domain->ops->set_dev_pasid(domain, dev, pasid);
+ if (ret)
+ xa_erase(&group->pasid_array, pasid);
+out_unlock:
+ mutex_unlock(&group->mutex);
+ iommu_group_put(group);
+
+ return ret;
+}
+
+void iommu_detach_device_pasid(struct iommu_domain *domain, struct
device *dev,
+ ioasid_t pasid)
+{
+ struct iommu_group *group = iommu_group_get(dev);
+
+ mutex_lock(&group->mutex);
+ domain->ops->block_dev_pasid(domain, dev, pasid);
+ xa_erase(&group->pasid_array, pasid);
+ mutex_unlock(&group->mutex);
+
+ iommu_group_put(group);
+}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 3fbad42c0bf8..9173c5741447 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -64,6 +64,9 @@ struct iommu_domain_geometry {
#define __IOMMU_DOMAIN_PT (1U << 2) /* Domain is identity mapped */
#define __IOMMU_DOMAIN_DMA_FQ (1U << 3) /* DMA-API uses flush queue */
+#define __IOMMU_DOMAIN_SHARED (1U << 4) /* Page table shared from CPU */
+#define __IOMMU_DOMAIN_HOST_VA (1U << 5) /* Host CPU virtual address */
+
/*
* This are the possible domain-types
*
@@ -86,15 +89,24 @@ struct iommu_domain_geometry {
#define IOMMU_DOMAIN_DMA_FQ (__IOMMU_DOMAIN_PAGING | \
__IOMMU_DOMAIN_DMA_API | \
__IOMMU_DOMAIN_DMA_FQ)
+#define IOMMU_DOMAIN_SVA (__IOMMU_DOMAIN_SHARED | \
+ __IOMMU_DOMAIN_HOST_VA)
struct iommu_domain {
unsigned type;
const struct iommu_domain_ops *ops;
unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
- iommu_fault_handler_t handler;
- void *handler_token;
struct iommu_domain_geometry geometry;
struct iommu_dma_cookie *iova_cookie;
+ union {
+ struct { /* IOMMU_DOMAIN_DMA */
+ iommu_fault_handler_t handler;
+ void *handler_token;
+ };
+ struct { /* IOMMU_DOMAIN_SVA */
+ struct mm_struct *mm;
+ };
+ };
};
static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
@@ -262,6 +274,8 @@ struct iommu_ops {
* struct iommu_domain_ops - domain specific operations
* @attach_dev: attach an iommu domain to a device
* @detach_dev: detach an iommu domain from a device
+ * @set_dev_pasid: set an iommu domain to a pasid of device
+ * @block_dev_pasid: block pasid of device from using iommu domain
* @map: map a physically contiguous memory region to an iommu domain
* @map_pages: map a physically contiguous set of pages of the same
size to
* an iommu domain.
@@ -282,6 +296,10 @@ struct iommu_ops {
struct iommu_domain_ops {
int (*attach_dev)(struct iommu_domain *domain, struct device *dev);
void (*detach_dev)(struct iommu_domain *domain, struct device *dev);
+ int (*set_dev_pasid)(struct iommu_domain *domain, struct device *dev,
+ ioasid_t pasid);
+ void (*block_dev_pasid)(struct iommu_domain *domain, struct device *dev,
+ ioasid_t pasid);
int (*map)(struct iommu_domain *domain, unsigned long iova,
phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
@@ -679,6 +697,12 @@ int iommu_group_claim_dma_owner(struct iommu_group
*group, void *owner);
void iommu_group_release_dma_owner(struct iommu_group *group);
bool iommu_group_dma_owner_claimed(struct iommu_group *group);
+struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
+ struct mm_struct *mm);
+int iommu_attach_device_pasid(struct iommu_domain *domain, struct
device *dev,
+ ioasid_t pasid);
+void iommu_detach_device_pasid(struct iommu_domain *domain, struct
device *dev,
+ ioasid_t pasid);
#else /* CONFIG_IOMMU_API */
struct iommu_ops {};
@@ -1052,6 +1076,23 @@ static inline bool
iommu_group_dma_owner_claimed(struct iommu_group *group)
{
return false;
}
+
+static inline struct iommu_domain *
+iommu_sva_domain_alloc(struct device *dev, struct mm_struct *mm)
+{
+ return NULL;
+}
+
+static inline int iommu_attach_device_pasid(struct iommu_domain *domain,
+ struct device *dev, ioasid_t pasid)
+{
+ return -ENODEV;
+}
+
+static inline void iommu_detach_device_pasid(struct iommu_domain *domain,
+ struct device *dev, ioasid_t pasid)
+{
+}
#endif /* CONFIG_IOMMU_API */
/**
--
2.25.1
Best regards,
baolu
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