On 12/20/2014 10:27 PM, Oded Gabbay wrote:
On 12/20/2014 10:12 PM, Oded Gabbay wrote:
This patch adds a new exported function to amd_iommu_v2, which returns 1 if the
amd_iommu_v2 initialization function has completed, and 0 otherwise.
This is necessary for the case when amd_iommu_v2 is compiled inside the kernel
image (not as module) and another module (e.g. amdkfd), which is also compiled
inside the kernel image, is dependent on amd_iommu_v2 functionality.
In that case, there is no mechanism in the kernel that enforces the order of
loading between the two modules. Therefore, If the amd_iommu_v2 is loaded
_after_ the other module, and the other module calls one of
amd_iommu_v2 exported functions _before_ amd_iommu_v2 is loaded, than that
function will fail, and as a result, the calling module may fail as well.
Note that when the two modules are compiled as modules, this situation can't
occur as the kernel enforces the order of loading.
Signed-off-by: Oded Gabbay <[email protected]>
---
drivers/iommu/amd_iommu_v2.c | 11 +++++++++++
include/linux/amd-iommu.h | 2 ++
2 files changed, 13 insertions(+)
diff --git a/drivers/iommu/amd_iommu_v2.c b/drivers/iommu/amd_iommu_v2.c
index 1e6360e..2456f18 100644
--- a/drivers/iommu/amd_iommu_v2.c
+++ b/drivers/iommu/amd_iommu_v2.c
@@ -895,6 +895,14 @@ out_unlock:
}
EXPORT_SYMBOL(amd_iommu_set_invalidate_ctx_cb);
+static int iommu_v2_init_completed;
+
+int amd_iommu_v2_is_init_completed(void)
+{
+ return iommu_v2_init_completed;
+}
+EXPORT_SYMBOL(amd_iommu_v2_is_init_completed);
+
static int __init amd_iommu_v2_init(void)
{
int ret;
@@ -903,6 +911,7 @@ static int __init amd_iommu_v2_init(void)
if (!amd_iommu_v2_supported()) {
pr_info("AMD IOMMUv2 functionality not available on this
system\n");
+ iommu_v2_init_completed = 1;
/*
* Load anyway to provide the symbols to other modules
* which may use AMD IOMMUv2 optionally.
@@ -919,6 +928,8 @@ static int __init amd_iommu_v2_init(void)
amd_iommu_register_ppr_notifier(&ppr_nb);
+ iommu_v2_init_completed = 1;
+
return 0;
out:
diff --git a/include/linux/amd-iommu.h b/include/linux/amd-iommu.h
index 2b08e79..115c03a 100644
--- a/include/linux/amd-iommu.h
+++ b/include/linux/amd-iommu.h
@@ -169,6 +169,8 @@ typedef void (*amd_iommu_invalidate_ctx)(struct pci_dev
*pdev, int pasid);
extern int amd_iommu_set_invalidate_ctx_cb(struct pci_dev *pdev,
amd_iommu_invalidate_ctx cb);
+extern int amd_iommu_v2_is_init_completed(void);
+
#else
static inline int amd_iommu_detect(void) { return -ENODEV; }
Hi Joerg,
This patch follows our IRC conversations from the last week.
Last update from me was that using subsys_initcall instead of module_init
does enforce amd_iommu_v2 to load _before_ amdkfd (apparently I didn't check
it correctly the first time). However, this won't help us because:
1. I don't know what effect this has when amd_iommu_v2 is compiled as module.
2. amd_iommu_v2 depends on amd_iommu which is not subsys, so amd_iommu_v2
init function fails when it is called this early, and thus, amd_iommu_v2
doesn't work.
I want to fix this situation in rc1/2, so I'm sending the complementary
patches to dri-devel in the meantime.
Oded
_______________________________________________
iommu mailing list
[email protected]
https://lists.linuxfoundation.org/mailman/listinfo/iommu
Hi,
The drm guys suggested we move iommu/ subsystem before gpu/ subsystem in
drivers/Makefile instead of the above patch (and the complementing patch-set in
amdkfd).
I did that and it works, so please see this patch as discarded for now.
I will send a new patch-set shortly.
ODed
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