Re: [PATCH] iommu: check for the deferred attach when attaching a device
From: Robin Murphy
Date: Fri Jan 15 2021 - 10:16:28 EST
On 2021-01-15 14:26, lijiang wrote:
Hi, Robin
Thank you for the comment.
在 2021年01月13日 01:29, Robin Murphy 写道:
On 2021-01-05 07:52, lijiang wrote:
在 2021年01月05日 11:55, lijiang 写道:
Hi,
Also add Joerg to cc list.
Also add more people to cc list, Jerry Snitselaar and Tom Lendacky.
Thanks.
Thanks.
Lianbo
在 2020年12月26日 13:39, Lianbo Jiang 写道:
Currently, because domain attach allows to be deferred from iommu
driver to device driver, and when iommu initializes, the devices
on the bus will be scanned and the default groups will be allocated.
Due to the above changes, some devices could be added to the same
group as below:
[ 3.859417] pci 0000:01:00.0: Adding to iommu group 16
[ 3.864572] pci 0000:01:00.1: Adding to iommu group 16
[ 3.869738] pci 0000:02:00.0: Adding to iommu group 17
[ 3.874892] pci 0000:02:00.1: Adding to iommu group 17
But when attaching these devices, it doesn't allow that a group has
more than one device, otherwise it will return an error. This conflicts
with the deferred attaching. Unfortunately, it has two devices in the
same group for my side, for example:
[ 9.627014] iommu_group_device_count(): device name[0]:0000:01:00.0
[ 9.633545] iommu_group_device_count(): device name[1]:0000:01:00.1
...
[ 10.255609] iommu_group_device_count(): device name[0]:0000:02:00.0
[ 10.262144] iommu_group_device_count(): device name[1]:0000:02:00.1
Finally, which caused the failure of tg3 driver when tg3 driver calls
the dma_alloc_coherent() to allocate coherent memory in the tg3_test_dma().
[ 9.660310] tg3 0000:01:00.0: DMA engine test failed, aborting
[ 9.754085] tg3: probe of 0000:01:00.0 failed with error -12
[ 9.997512] tg3 0000:01:00.1: DMA engine test failed, aborting
[ 10.043053] tg3: probe of 0000:01:00.1 failed with error -12
[ 10.288905] tg3 0000:02:00.0: DMA engine test failed, aborting
[ 10.334070] tg3: probe of 0000:02:00.0 failed with error -12
[ 10.578303] tg3 0000:02:00.1: DMA engine test failed, aborting
[ 10.622629] tg3: probe of 0000:02:00.1 failed with error -12
In addition, the similar situations also occur in other drivers such
as the bnxt_en driver. That can be reproduced easily in kdump kernel
when SME is active.
Add a check for the deferred attach in the iommu_attach_device() and
allow to attach the deferred device regardless of how many devices
are in a group.
Is this iommu_attach_device() call is coming from iommu-dma? (if not, then whoever's calling it probably shouldn't be)
Yes, you are right, the iommu_attach_device call is coming from iommu-dma.
Assuming so, then probably what should happen is to move the handling currently in iommu_dma_deferred_attach() into the core so that it can call __iommu_attach_device() directly - the intent is just to replay that exact call skipped in iommu_group_add_device(), so the legacy external iommu_attach_device() interface isn't really the right tool for the job
Sounds good. I will check if this can work in various cases. If it's OK, I will post again.
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index f0305e6aac1b..5e7da902ac36 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -23,7 +23,6 @@
#include <linux/swiotlb.h>
#include <linux/scatterlist.h>
#include <linux/vmalloc.h>
-#include <linux/crash_dump.h>
#include <linux/dma-direct.h>
struct iommu_dma_msi_page {
@@ -378,21 +377,6 @@ static int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
return iova_reserve_iommu_regions(dev, domain);
}
-static int iommu_dma_deferred_attach(struct device *dev,
- struct iommu_domain *domain)
-{
- const struct iommu_ops *ops = domain->ops;
-
- if (!is_kdump_kernel())
- return 0;
-
- if (unlikely(ops->is_attach_deferred &&
- ops->is_attach_deferred(domain, dev)))
- return iommu_attach_device(domain, dev);
-
- return 0;
-}
-
/**
* dma_info_to_prot - Translate DMA API directions and attributes to IOMMU API
* page flags.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index ffeebda8d6de..4fed1567b498 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -23,6 +23,7 @@
#include <linux/property.h>
#include <linux/fsl/mc.h>
#include <linux/module.h>
+#include <linux/crash_dump.h>
#include <trace/events/iommu.h>
static struct kset *iommu_group_kset;
@@ -1952,6 +1953,21 @@ static int __iommu_attach_device(struct iommu_domain *domain,
return ret;
}
+int iommu_dma_deferred_attach(struct device *dev,
+ struct iommu_domain *domain)
+{
+ const struct iommu_ops *ops = domain->ops;
+
+ if (!is_kdump_kernel())
+ return 0;
+
+ if (unlikely(ops->is_attach_deferred &&
+ ops->is_attach_deferred(domain, dev)))
+ return __iommu_attach_device(domain, dev);
+
+ return 0;
+}
+
int iommu_attach_device(struct iommu_domain *domain, struct device *dev)
{
struct iommu_group *group;
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index b3f0e2018c62..8e0ee96ca456 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -424,6 +424,8 @@ extern struct iommu_group *iommu_group_get_by_id(int id);
extern void iommu_domain_free(struct iommu_domain *domain);
extern int iommu_attach_device(struct iommu_domain *domain,
struct device *dev);
+extern int iommu_dma_deferred_attach(struct device *dev,
+ struct iommu_domain *domain);
extern void iommu_detach_device(struct iommu_domain *domain,
struct device *dev);
extern int iommu_uapi_cache_invalidate(struct iommu_domain *domain,
@@ -680,6 +682,12 @@ static inline int iommu_attach_device(struct iommu_domain *domain,
return -ENODEV;
}
+static inline int iommu_dma_deferred_attach(struct device *dev,
+ struct iommu_domain *domain)
+{
+ return -ENODEV;
+}
+
static inline void iommu_detach_device(struct iommu_domain *domain,
struct device *dev)
{
Yeah, that's more or less what I had in mind (FWIW I don't think we need
the stub definition since this should only ever be called by other
IOMMU-API-dependent code). However I'd really like to minimise the
fast-path impact to the normal case, so how about throwing something
like this into the mix as well? (where iommu_do_deferred_attach()
represents what you have above minus the move of the kdump check)
Cheers,
Robin.
----->8-----
diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 4078358ed66e..638222558248 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -51,6 +51,8 @@ struct iommu_dma_cookie {
struct iommu_domain *fq_domain;
};
+DEFINE_STATIC_KEY_FALSE(deferred_attach);
+
void iommu_dma_free_cpu_cached_iovas(unsigned int cpu,
struct iommu_domain *domain)
{
@@ -378,21 +380,6 @@ static int iommu_dma_init_domain(struct
iommu_domain *domain, dma_addr_t base,
return iova_reserve_iommu_regions(dev, domain);
}
-static int iommu_dma_deferred_attach(struct device *dev,
- struct iommu_domain *domain)
-{
- const struct iommu_ops *ops = domain->ops;
-
- if (!is_kdump_kernel())
- return 0;
-
- if (unlikely(ops->is_attach_deferred &&
- ops->is_attach_deferred(domain, dev)))
- return iommu_attach_device(domain, dev);
-
- return 0;
-}
-
/**
* dma_info_to_prot - Translate DMA API directions and attributes to
IOMMU API
* page flags.
@@ -535,7 +522,8 @@ static dma_addr_t __iommu_dma_map(struct device
*dev, phys_addr_t phys,
size_t iova_off = iova_offset(iovad, phys);
dma_addr_t iova;
- if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+ if (static_branch_unlikely(&deferred_attach) &&
+ iommu_do_deferred_attach(domain, dev))
return DMA_MAPPING_ERROR;
size = iova_align(iovad, size + iova_off);
@@ -693,7 +681,8 @@ static void *iommu_dma_alloc_remap(struct device
*dev, size_t size,
*dma_handle = DMA_MAPPING_ERROR;
- if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+ if (static_branch_unlikely(&deferred_attach) &&
+ iommu_do_deferred_attach(domain, dev))
return NULL;
min_size = alloc_sizes & -alloc_sizes;
@@ -976,7 +965,8 @@ static int iommu_dma_map_sg(struct device *dev,
struct scatterlist *sg,
unsigned long mask = dma_get_seg_boundary(dev);
int i;
- if (unlikely(iommu_dma_deferred_attach(dev, domain)))
+ if (static_branch_unlikely(&deferred_attach) &&
+ iommu_do_deferred_attach(domain, dev))
return 0;
if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
@@ -1424,6 +1414,9 @@ void iommu_dma_compose_msi_msg(struct msi_desc *desc,
static int iommu_dma_init(void)
{
+ if (is_kdump_kernel())
+ static_branch_enable(&deferred_attach);
+
return iova_cache_get();
}
arch_initcall(iommu_dma_init);