From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: devicetree@vger.kernel.org, kevin.tian@intel.com, jgg@ziepe.ca,
linux-pci@vger.kernel.org, robin.murphy@arm.com,
fenghua.yu@intel.com, hch@infradead.org, linux-mm@kvack.org,
iommu@lists.linux-foundation.org, zhangfei.gao@linaro.org,
catalin.marinas@arm.com, felix.kuehling@amd.com, will@kernel.org,
christian.koenig@amd.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v6 02/25] iommu/ioasid: Add ioasid references
Date: Thu, 30 Apr 2020 11:39:31 -0700 [thread overview]
Message-ID: <20200430113931.0fbf7a37@jacob-builder> (raw)
In-Reply-To: <20200430143424.2787566-3-jean-philippe@linaro.org>
On Thu, 30 Apr 2020 16:34:01 +0200
Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:
> Let IOASID users take references to existing ioasids with
> ioasid_get(). ioasid_free() drops a reference and only frees the
> ioasid when its reference number is zero. It returns whether the
> ioasid was freed.
>
Looks good to me, I was planning to do the same for VT-d use. Just a
couple of points for potential extension. I can rebase on top of this.
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> ---
> include/linux/ioasid.h | 10 ++++++++--
> drivers/iommu/ioasid.c | 30 +++++++++++++++++++++++++++++-
> 2 files changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h
> index 6f000d7a0ddcd..609ba6f15b9e3 100644
> --- a/include/linux/ioasid.h
> +++ b/include/linux/ioasid.h
> @@ -34,7 +34,8 @@ struct ioasid_allocator_ops {
> #if IS_ENABLED(CONFIG_IOASID)
> ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t
> max, void *private);
> -void ioasid_free(ioasid_t ioasid);
> +void ioasid_get(ioasid_t ioasid);
> +bool ioasid_free(ioasid_t ioasid);
> void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,
> bool (*getter)(void *));
> int ioasid_register_allocator(struct ioasid_allocator_ops
> *allocator); @@ -48,10 +49,15 @@ static inline ioasid_t
> ioasid_alloc(struct ioasid_set *set, ioasid_t min, return
> INVALID_IOASID; }
>
> -static inline void ioasid_free(ioasid_t ioasid)
> +static inline void ioasid_get(ioasid_t ioasid)
> {
> }
>
> +static inline bool ioasid_free(ioasid_t ioasid)
> +{
> + return false;
> +}
> +
> static inline void *ioasid_find(struct ioasid_set *set, ioasid_t
> ioasid, bool (*getter)(void *))
> {
> diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c
> index 0f8dd377aada3..46511ac53e0c8 100644
> --- a/drivers/iommu/ioasid.c
> +++ b/drivers/iommu/ioasid.c
> @@ -15,6 +15,7 @@ struct ioasid_data {
> struct ioasid_set *set;
> void *private;
> struct rcu_head rcu;
> + refcount_t refs;
> };
>
> /*
> @@ -314,6 +315,7 @@ ioasid_t ioasid_alloc(struct ioasid_set *set,
> ioasid_t min, ioasid_t max,
> data->set = set;
> data->private = private;
> + refcount_set(&data->refs, 1);
>
> /*
> * Custom allocator needs allocator data to perform platform
> specific @@ -345,12 +347,33 @@ ioasid_t ioasid_alloc(struct
> ioasid_set *set, ioasid_t min, ioasid_t max, }
> EXPORT_SYMBOL_GPL(ioasid_alloc);
>
> +/**
> + * ioasid_get - obtain a reference to the IOASID
> + */
> +void ioasid_get(ioasid_t ioasid)
why void? what if the ioasid is not valid.
> +{
> + struct ioasid_data *ioasid_data;
> +
> + spin_lock(&ioasid_allocator_lock);
> + ioasid_data = xa_load(&active_allocator->xa, ioasid);
> + if (ioasid_data)
> + refcount_inc(&ioasid_data->refs);
> + spin_unlock(&ioasid_allocator_lock);
> +}
> +EXPORT_SYMBOL_GPL(ioasid_get);
> +
> /**
> * ioasid_free - Free an IOASID
> * @ioasid: the ID to remove
> + *
> + * Put a reference to the IOASID, free it when the number of
> references drops to
> + * zero.
> + *
> + * Return: %true if the IOASID was freed, %false otherwise.
> */
> -void ioasid_free(ioasid_t ioasid)
> +bool ioasid_free(ioasid_t ioasid)
> {
> + bool free = false;
> struct ioasid_data *ioasid_data;
>
> spin_lock(&ioasid_allocator_lock);
> @@ -360,6 +383,10 @@ void ioasid_free(ioasid_t ioasid)
> goto exit_unlock;
> }
>
> + free = refcount_dec_and_test(&ioasid_data->refs);
> + if (!free)
> + goto exit_unlock;
> +
Just FYI, we may need to add states for the IOASID, i.g. mark the IOASID
inactive after free. And prohibit ioasid_get() after freed. For VT-d,
this is useful when KVM queries the IOASID.
> active_allocator->ops->free(ioasid,
> active_allocator->ops->pdata); /* Custom allocator needs additional
> steps to free the xa element */ if (active_allocator->flags &
> IOASID_ALLOCATOR_CUSTOM) { @@ -369,6 +396,7 @@ void
> ioasid_free(ioasid_t ioasid)
> exit_unlock:
> spin_unlock(&ioasid_allocator_lock);
> + return free;
> }
> EXPORT_SYMBOL_GPL(ioasid_free);
>
[Jacob Pan]
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iommu@lists.linux-foundation.org
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next prev parent reply other threads:[~2020-04-30 18:33 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-30 14:33 [PATCH v6 00/25] iommu: Shared Virtual Addressing for SMMUv3 Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 01/25] mm: Add a PASID field to mm_struct Jean-Philippe Brucker
2020-05-04 1:52 ` Xu Zaibo
2020-05-04 16:29 ` Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 02/25] iommu/ioasid: Add ioasid references Jean-Philippe Brucker
2020-04-30 18:39 ` Jacob Pan [this message]
2020-04-30 20:48 ` Jacob Pan
2020-05-04 14:39 ` Jean-Philippe Brucker
2020-05-04 15:22 ` Jacob Pan
2020-05-04 14:25 ` Jean-Philippe Brucker
2020-05-04 15:27 ` Jacob Pan
2020-04-30 14:34 ` [PATCH v6 03/25] iommu/sva: Add PASID helpers Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 04/25] iommu: Add a page fault handler Jean-Philippe Brucker
2020-05-03 5:49 ` Lu Baolu
2020-05-04 16:22 ` Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 05/25] iommu/iopf: Handle mm faults Jean-Philippe Brucker
2020-05-03 5:54 ` Lu Baolu
2020-05-04 16:25 ` Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 06/25] arm64: mm: Add asid_gen_match() helper Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 07/25] arm64: mm: Pin down ASIDs for sharing mm with devices Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 08/25] iommu/io-pgtable-arm: Move some definitions to a header Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 09/25] iommu/arm-smmu-v3: Manage ASIDs with xarray Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 10/25] arm64: cpufeature: Export symbol read_sanitised_ftr_reg() Jean-Philippe Brucker
2020-04-30 15:18 ` Suzuki K Poulose
2020-04-30 14:34 ` [PATCH v6 11/25] iommu/arm-smmu-v3: Share process page tables Jean-Philippe Brucker
2020-04-30 15:39 ` Suzuki K Poulose
2020-05-04 14:11 ` Jean-Philippe Brucker
2020-05-04 14:42 ` Suzuki K Poulose
2020-04-30 14:34 ` [PATCH v6 12/25] iommu/arm-smmu-v3: Seize private ASID Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 13/25] iommu/arm-smmu-v3: Add support for VHE Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 14/25] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 15/25] iommu/arm-smmu-v3: Add SVA feature checking Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 16/25] iommu/arm-smmu-v3: Add SVA device feature Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 17/25] iommu/arm-smmu-v3: Implement iommu_sva_bind/unbind() Jean-Philippe Brucker
2020-04-30 21:16 ` Jacob Pan
2020-05-04 16:43 ` Jean-Philippe Brucker
2020-05-04 20:47 ` Jacob Pan
2020-05-05 9:15 ` Jean-Philippe Brucker
2020-05-07 16:31 ` Jacob Pan
2020-05-01 12:15 ` Christoph Hellwig
2020-05-01 12:55 ` Jason Gunthorpe
2020-05-04 16:07 ` Jean-Philippe Brucker
2020-05-04 16:06 ` Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 18/25] iommu/arm-smmu-v3: Hook up ATC invalidation to mm ops Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 19/25] iommu/arm-smmu-v3: Add support for Hardware Translation Table Update Jean-Philippe Brucker
2020-05-04 14:24 ` Prabhakar Kushwaha
2020-05-04 16:35 ` Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 20/25] iommu/arm-smmu-v3: Maintain a SID->device structure Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 21/25] dt-bindings: document stall property for IOMMU masters Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 22/25] iommu/arm-smmu-v3: Add stall support for platform devices Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 23/25] PCI/ATS: Add PRI stubs Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 24/25] PCI/ATS: Export PRI functions Jean-Philippe Brucker
2020-04-30 14:34 ` [PATCH v6 25/25] iommu/arm-smmu-v3: Add support for PRI Jean-Philippe Brucker
2020-04-30 21:18 ` [PATCH v6 00/25] iommu: Shared Virtual Addressing for SMMUv3 Jacob Pan
2020-05-04 15:09 ` Jean-Philippe Brucker
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