Messages in this thread | | | Date | Mon, 22 Dec 2014 12:23:44 +0200 | From | Oded Gabbay <> | Subject | Re: [PATCH] iommu/amd: Track when amd_iommu_v2 init is complete |
| |
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 <oded.gabbay@amd.com> >> --- >> 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 > iommu@lists.linux-foundation.org > 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
| |