linux-kernel - Re: [PATCH v2 3/3] iommu: Remove ioasid infrastructure

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Message-ID: <Y+tVMRzRQbcc7Guz@myrica>
Date:   Tue, 14 Feb 2023 09:32:33 +0000
From:   Jean-Philippe Brucker <jean-philippe@...aro.org>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, iommu@...ts.linux.dev,
        Jason Gunthorpe <jgg@...dia.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will@...nel.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>
Subject: Re: [PATCH v2 3/3] iommu: Remove ioasid infrastructure

On Mon, Feb 13, 2023 at 10:44:14PM -0800, Jacob Pan wrote:
> This has no use anymore, delete it all.
> 
> Signed-off-by: Jason Gunthorpe <jgg@...dia.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>

Yes, a number of intended users haven't materialized yet. They can
re-introduce the allocator when they need it.

> ---
> v2:
> 	- fix compile issue w/o CONFIG_IOMMU_SVA
> 	- consolidate INVALID_IOASID w/ IOMMU_PASID_INVALID

Why not rename ioasid_t as well?  Probably better to move all the renaming
to a separate patch

> ---
>  Documentation/x86/sva.rst   |   2 +-
>  arch/x86/kernel/traps.c     |   5 +-
>  drivers/dma/idxd/device.c   |   8 +-
>  drivers/dma/idxd/idxd.h     |   1 -
>  drivers/dma/idxd/init.c     |   2 +-
>  drivers/dma/idxd/irq.c      |   2 +-
>  drivers/iommu/intel/dmar.c  |   4 +-
>  drivers/iommu/intel/iommu.c |   2 +-
>  drivers/iommu/intel/iommu.h |   1 -
>  drivers/iommu/intel/svm.c   |   3 +-
>  drivers/iommu/ioasid.c      | 422 ------------------------------------
>  drivers/iommu/iommu-sva.c   |   2 +-
>  drivers/iommu/iommu-sva.h   |   1 -
>  include/linux/ioasid.h      |  83 -------
>  include/linux/iommu.h       |  11 +-
>  include/linux/sched/mm.h    |   4 +-
>  include/uapi/linux/iommu.h  |   1 +
>  mm/init-mm.c                |   4 +-

drivers/iommu/{Makefile,Kconfig} also need updates

>  18 files changed, 29 insertions(+), 529 deletions(-)
>  delete mode 100644 drivers/iommu/ioasid.c
>  delete mode 100644 include/linux/ioasid.h

> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 46e1347bfa22..7cbcf37df8cd 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -13,7 +13,6 @@
>  #include <linux/errno.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> -#include <linux/ioasid.h>
>  #include <uapi/linux/iommu.h>
>  
>  #define IOMMU_READ	(1 << 0)
> @@ -192,8 +191,14 @@ enum iommu_dev_features {
>  	IOMMU_DEV_FEAT_IOPF,
>  };
>  
> -#define IOMMU_PASID_INVALID	(-1U)
> -
> +//#define IOMMU_PASID_INVALID	(-1U)

Remove this

> +typedef unsigned int ioasid_t;
> +#ifdef CONFIG_IOMMU_SVA
> +static inline bool pasid_valid(ioasid_t ioasid)
> +{
> +	return ioasid != IOMMU_PASID_INVALID;
> +}
> +#endif

This isn't specific to SVA, doesn't need an ifdef

>  #ifdef CONFIG_IOMMU_API
>  
>  /**
> diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
> index cdc138086230..4c52835d3359 100644
> --- a/include/linux/sched/mm.h
> +++ b/include/linux/sched/mm.h
> @@ -8,7 +8,7 @@
>  #include <linux/mm_types.h>
>  #include <linux/gfp.h>
>  #include <linux/sync_core.h>
> -#include <linux/ioasid.h>
> +#include <uapi/linux/iommu.h>
>  
>  /*
>   * Routines for handling mm_structs
> @@ -454,7 +454,7 @@ static inline void membarrier_update_current_mm(struct mm_struct *next_mm)
>  #ifdef CONFIG_IOMMU_SVA
>  static inline void mm_pasid_init(struct mm_struct *mm)
>  {
> -	mm->pasid = INVALID_IOASID;
> +	mm->pasid = IOMMU_PASID_INVALID;
>  }
>  
>  /* Associate a PASID with an mm_struct: */
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 65d8b0234f69..a95f07f0c98c 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -157,5 +157,6 @@ struct iommu_page_response {
>  	__u32	grpid;
>  	__u32	code;
>  };
> +#define IOMMU_PASID_INVALID	(-1U)

Why change UAPI?

Thanks,
Jean

>  
>  #endif /* _UAPI_IOMMU_H */
> diff --git a/mm/init-mm.c b/mm/init-mm.c
> index c9327abb771c..a084039f55d8 100644
> --- a/mm/init-mm.c
> +++ b/mm/init-mm.c
> @@ -10,7 +10,7 @@
>  
>  #include <linux/atomic.h>
>  #include <linux/user_namespace.h>
> -#include <linux/ioasid.h>
> +#include <linux/iommu.h>
>  #include <asm/mmu.h>
>  
>  #ifndef INIT_MM_CONTEXT
> @@ -40,7 +40,7 @@ struct mm_struct init_mm = {
>  	.user_ns	= &init_user_ns,
>  	.cpu_bitmap	= CPU_BITS_NONE,
>  #ifdef CONFIG_IOMMU_SVA
> -	.pasid		= INVALID_IOASID,
> +	.pasid		= IOMMU_PASID_INVALID,
>  #endif
>  	INIT_MM_CONTEXT(init_mm)
>  };
> -- 
> 2.25.1
>