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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: Jacob Pan <jacob.pan.linux@gmail.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Raj Ashok <ashok.raj@intel.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	LKML <linux-kernel@vger.kernel.org>,
	iommu@lists.linux-foundation.org, Wu Hao <hao.wu@intel.com>,
	David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH v2 5/9] iommu/ioasid: Introduce ioasid_set private ID
Date: Tue, 25 Aug 2020 12:22:09 +0200	[thread overview]
Message-ID: <20200825102209.GC3252704@myrica> (raw)
In-Reply-To: <1598070918-21321-6-git-send-email-jacob.jun.pan@linux.intel.com>

On Fri, Aug 21, 2020 at 09:35:14PM -0700, Jacob Pan wrote:
> When an IOASID set is used for guest SVA, each VM will acquire its
> ioasid_set for IOASID allocations. IOASIDs within the VM must have a
> host/physical IOASID backing, mapping between guest and host IOASIDs can
> be non-identical. IOASID set private ID (SPID) is introduced in this
> patch to be used as guest IOASID. However, the concept of ioasid_set
> specific namespace is generic, thus named SPID.
> 
> As SPID namespace is within the IOASID set, the IOASID core can provide
> lookup services at both directions. SPIDs may not be allocated when its
> IOASID is allocated, the mapping between SPID and IOASID is usually
> established when a guest page table is bound to a host PASID.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> ---
>  drivers/iommu/ioasid.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/ioasid.h | 12 +++++++++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
> index 5f31d63c75b1..c0aef38a4fde 100644
> --- a/drivers/iommu/ioasid.c
> +++ b/drivers/iommu/ioasid.c
> @@ -21,6 +21,7 @@ enum ioasid_state {
>   * struct ioasid_data - Meta data about ioasid
>   *
>   * @id:		Unique ID
> + * @spid:	Private ID unique within a set
>   * @users	Number of active users
>   * @state	Track state of the IOASID
>   * @set		Meta data of the set this IOASID belongs to
> @@ -29,6 +30,7 @@ enum ioasid_state {
>   */
>  struct ioasid_data {
>  	ioasid_t id;
> +	ioasid_t spid;
>  	struct ioasid_set *set;
>  	refcount_t users;
>  	enum ioasid_state state;
> @@ -326,6 +328,58 @@ int ioasid_attach_data(ioasid_t ioasid, void *data)
>  EXPORT_SYMBOL_GPL(ioasid_attach_data);
>  
>  /**
> + * ioasid_attach_spid - Attach ioasid_set private ID to an IOASID
> + *
> + * @ioasid: the ID to attach
> + * @spid:   the ioasid_set private ID of @ioasid
> + *
> + * For IOASID that is already allocated, private ID within the set can be
> + * attached via this API. Future lookup can be done via ioasid_find.

via ioasid_find_by_spid()?

> + */
> +int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid)
> +{
> +	struct ioasid_data *ioasid_data;
> +	int ret = 0;
> +
> +	spin_lock(&ioasid_allocator_lock);
> +	ioasid_data = xa_load(&active_allocator->xa, ioasid);
> +
> +	if (!ioasid_data) {
> +		pr_err("No IOASID entry %d to attach SPID %d\n",
> +			ioasid, spid);
> +		ret = -ENOENT;
> +		goto done_unlock;
> +	}
> +	ioasid_data->spid = spid;
> +
> +done_unlock:
> +	spin_unlock(&ioasid_allocator_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(ioasid_attach_spid);
> +
> +ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid)

Maybe add a bit of documentation as this is public-facing.

> +{
> +	struct ioasid_data *entry;
> +	unsigned long index;
> +
> +	if (!xa_load(&ioasid_sets, set->sid)) {
> +		pr_warn("Invalid set\n");
> +		return INVALID_IOASID;
> +	}
> +
> +	xa_for_each(&set->xa, index, entry) {
> +		if (spid == entry->spid) {
> +			pr_debug("Found ioasid %lu by spid %u\n", index, spid);
> +			refcount_inc(&entry->users);

Nothing prevents ioasid_free() from concurrently dropping the refcount to
zero and calling ioasid_do_free(). The caller will later call ioasid_put()
on a stale/reallocated index.

> +			return index;
> +		}
> +	}
> +	return INVALID_IOASID;
> +}
> +EXPORT_SYMBOL_GPL(ioasid_find_by_spid);
> +
> +/**
>   * ioasid_alloc - Allocate an IOASID
>   * @set: the IOASID set
>   * @min: the minimum ID (inclusive)
> diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
> index 310abe4187a3..d4b3e83672f6 100644
> --- a/include/linux/ioasid.h
> +++ b/include/linux/ioasid.h
> @@ -73,6 +73,8 @@ bool ioasid_is_active(ioasid_t ioasid);
>  
>  void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid, bool (*getter)(void *));
>  int ioasid_attach_data(ioasid_t ioasid, void *data);
> +int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid);
> +ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid);
>  int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
>  void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator);
>  void ioasid_is_in_set(struct ioasid_set *set, ioasid_t ioasid);
> @@ -136,5 +138,15 @@ static inline int ioasid_attach_data(ioasid_t ioasid, void *data)
>  	return -ENOTSUPP;
>  }
>  
> +staic inline int ioasid_attach_spid(ioasid_t ioasid, ioasid_t spid)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static inline ioasid_t ioasid_find_by_spid(struct ioasid_set *set, ioasid_t spid)
> +{
> +	return -ENOTSUPP;

INVALID_IOASID

Thanks,
Jean

> +}
> +
>  #endif /* CONFIG_IOASID */
>  #endif /* __LINUX_IOASID_H */
> -- 
> 2.7.4
> 
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  parent reply	other threads:[~2020-08-25 10:22 UTC|newest]

Thread overview: 56+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-22  4:35 [PATCH v2 0/9] IOASID extensions for guest SVA Jacob Pan
2020-08-22  4:35 ` [PATCH v2 1/9] docs: Document IO Address Space ID (IOASID) APIs Jacob Pan
2020-08-23  7:05   ` Lu Baolu
2020-08-28 17:01     ` Jacob Pan
2020-08-24 10:32   ` Jean-Philippe Brucker
2020-08-27 16:21     ` Auger Eric
2020-09-01 16:56       ` Jacob Pan
2020-09-07  8:03         ` Auger Eric
2020-09-08 17:29           ` Jacob Pan
2020-08-28 22:24     ` Jacob Pan
2020-08-22  4:35 ` [PATCH v2 2/9] iommu/ioasid: Rename ioasid_set_data() Jacob Pan
2020-08-24 18:29   ` Jean-Philippe Brucker
2020-09-01 11:51   ` Auger Eric
2020-08-22  4:35 ` [PATCH v2 3/9] iommu/ioasid: Introduce ioasid_set APIs Jacob Pan
2020-08-22 12:53   ` kernel test robot
2020-08-24  2:24   ` Lu Baolu
2020-09-01 21:28     ` Jacob Pan
2020-09-02  2:39       ` Lu Baolu
2020-08-24 18:28   ` Jean-Philippe Brucker
2020-08-24 18:30     ` Randy Dunlap
2020-09-02 21:46       ` Jacob Pan
2020-08-24 18:34     ` Randy Dunlap
2020-09-02 21:47       ` Jacob Pan
2020-09-02 21:44     ` Jacob Pan
2020-09-01 11:51   ` Auger Eric
2020-09-03 21:07     ` Jacob Pan
2020-09-07  8:04       ` Auger Eric
2020-08-22  4:35 ` [PATCH v2 4/9] iommu/ioasid: Add reference couting functions Jacob Pan
2020-08-24  2:26   ` Lu Baolu
2020-08-25 10:20     ` Jean-Philippe Brucker
2020-08-25 10:19   ` Jean-Philippe Brucker
2020-09-08 20:30     ` Jacob Pan
2020-09-01 12:13   ` Auger Eric
2020-09-08 20:49     ` Jacob Pan
2020-09-24 18:29   ` Shameerali Kolothum Thodi
2020-08-22  4:35 ` [PATCH v2 5/9] iommu/ioasid: Introduce ioasid_set private ID Jacob Pan
2020-08-22  8:36   ` kernel test robot
2020-08-22  9:03   ` kernel test robot
2020-08-25 10:22   ` Jean-Philippe Brucker [this message]
2020-09-08 22:19     ` Jacob Pan
2020-09-01 15:38   ` Auger Eric
2020-09-08 22:40     ` Jacob Pan
2020-09-10  9:18       ` Auger Eric
2020-08-22  4:35 ` [PATCH v2 6/9] iommu/ioasid: Introduce notification APIs Jacob Pan
2020-08-25 10:26   ` Jean-Philippe Brucker
2020-09-09 20:37     ` Jacob Pan
2020-09-01 16:49   ` Auger Eric
2020-09-09 22:58     ` Jacob Pan
2020-09-10  8:59       ` Auger Eric
2020-08-22  4:35 ` [PATCH v2 7/9] iommu/vt-d: Listen to IOASID notifications Jacob Pan
2020-09-01 17:03   ` Auger Eric
2020-09-10  4:54     ` Jacob Pan
2020-08-22  4:35 ` [PATCH v2 8/9] iommu/vt-d: Send IOASID bind/unbind notifications Jacob Pan
2020-08-22  4:35 ` [PATCH v2 9/9] iommu/vt-d: Store guest PASID during bind Jacob Pan
2020-09-01 17:08   ` Auger Eric
2020-09-10 17:12     ` Jacob Pan

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