From: David Gibson <david@gibson.dropbear.id.au>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org,
Alex Williamson <alex.williamson@redhat.com>,
Paul Mackerras <paulus@samba.org>,
kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH kernel v10 04/10] powerpc/vfio_spapr_tce: Add reference counting to iommu_table
Date: Wed, 22 Mar 2017 11:40:29 +1100 [thread overview]
Message-ID: <20170322004029.GC19078@umbus.fritz.box> (raw)
In-Reply-To: <20170317050959.37312-5-aik@ozlabs.ru>
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On Fri, Mar 17, 2017 at 04:09:53PM +1100, Alexey Kardashevskiy wrote:
> So far iommu_table obejcts were only used in virtual mode and had
> a single owner. We are going to change this by implementing in-kernel
> acceleration of DMA mapping requests. The proposed acceleration
> will handle requests in real mode and KVM will keep references to tables.
>
> This adds a kref to iommu_table and defines new helpers to update it.
> This replaces iommu_free_table() with iommu_tce_table_put() and makes
> iommu_free_table() static. iommu_tce_table_get() is not used in this patch
> but it will be in the following patch.
>
> Since this touches prototypes, this also removes @node_name parameter as
> it has never been really useful on powernv and carrying it for
> the pseries platform code to iommu_free_table() seems to be quite
> useless as well.
>
> This should cause no behavioral change.
>
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> Changes:
> v10:
> * iommu_tce_table_get() can fail now if a table is being destroyed, will be
> used in 10/10
> * iommu_tce_table_put() returns what kref_put() returned
> * iommu_tce_table_put() got WARN_ON(!tbl) as the callers already check
> for it and do not call _put() when tbl==NULL
>
> v9:
> * s/iommu_table_get/iommu_tce_table_get/ and
> s/iommu_table_put/iommu_tce_table_put/ -- so I removed r-b/a-b
> ---
> arch/powerpc/include/asm/iommu.h | 5 +++--
> arch/powerpc/kernel/iommu.c | 27 ++++++++++++++++++++++-----
> arch/powerpc/platforms/powernv/pci-ioda.c | 14 +++++++-------
> arch/powerpc/platforms/powernv/pci.c | 1 +
> arch/powerpc/platforms/pseries/iommu.c | 3 ++-
> arch/powerpc/platforms/pseries/vio.c | 2 +-
> drivers/vfio/vfio_iommu_spapr_tce.c | 2 +-
> 7 files changed, 37 insertions(+), 17 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
> index 4554699aec02..d96142572e6d 100644
> --- a/arch/powerpc/include/asm/iommu.h
> +++ b/arch/powerpc/include/asm/iommu.h
> @@ -119,6 +119,7 @@ struct iommu_table {
> struct list_head it_group_list;/* List of iommu_table_group_link */
> unsigned long *it_userspace; /* userspace view of the table */
> struct iommu_table_ops *it_ops;
> + struct kref it_kref;
> };
>
> #define IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry) \
> @@ -151,8 +152,8 @@ static inline void *get_iommu_table_base(struct device *dev)
>
> extern int dma_iommu_dma_supported(struct device *dev, u64 mask);
>
> -/* Frees table for an individual device node */
> -extern void iommu_free_table(struct iommu_table *tbl, const char *node_name);
> +extern struct iommu_table *iommu_tce_table_get(struct iommu_table *tbl);
> +extern int iommu_tce_table_put(struct iommu_table *tbl);
>
> /* Initializes an iommu_table based in values set in the passed-in
> * structure
> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
> index bc142d87130f..af915da5e03a 100644
> --- a/arch/powerpc/kernel/iommu.c
> +++ b/arch/powerpc/kernel/iommu.c
> @@ -711,13 +711,13 @@ struct iommu_table *iommu_init_table(struct iommu_table *tbl, int nid)
> return tbl;
> }
>
> -void iommu_free_table(struct iommu_table *tbl, const char *node_name)
> +static void iommu_table_free(struct kref *kref)
> {
> unsigned long bitmap_sz;
> unsigned int order;
> + struct iommu_table *tbl;
>
> - if (!tbl)
> - return;
> + tbl = container_of(kref, struct iommu_table, it_kref);
>
> if (tbl->it_ops->free)
> tbl->it_ops->free(tbl);
> @@ -736,7 +736,7 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
>
> /* verify that table contains no entries */
> if (!bitmap_empty(tbl->it_map, tbl->it_size))
> - pr_warn("%s: Unexpected TCEs for %s\n", __func__, node_name);
> + pr_warn("%s: Unexpected TCEs\n", __func__);
>
> /* calculate bitmap size in bytes */
> bitmap_sz = BITS_TO_LONGS(tbl->it_size) * sizeof(unsigned long);
> @@ -748,7 +748,24 @@ void iommu_free_table(struct iommu_table *tbl, const char *node_name)
> /* free table */
> kfree(tbl);
> }
> -EXPORT_SYMBOL_GPL(iommu_free_table);
> +
> +struct iommu_table *iommu_tce_table_get(struct iommu_table *tbl)
> +{
> + if (kref_get_unless_zero(&tbl->it_kref))
> + return tbl;
> +
> + return NULL;
> +}
> +EXPORT_SYMBOL_GPL(iommu_tce_table_get);
> +
> +int iommu_tce_table_put(struct iommu_table *tbl)
> +{
> + if (WARN_ON(!tbl))
> + return 0;
> +
> + return kref_put(&tbl->it_kref, iommu_table_free);
> +}
> +EXPORT_SYMBOL_GPL(iommu_tce_table_put);
>
> /* Creates TCEs for a user provided buffer. The user buffer must be
> * contiguous real kernel storage (not vmalloc). The address passed here
> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
> index 5dae54cb11e3..ee4cdb5b893f 100644
> --- a/arch/powerpc/platforms/powernv/pci-ioda.c
> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
> @@ -1424,7 +1424,7 @@ static void pnv_pci_ioda2_release_dma_pe(struct pci_dev *dev, struct pnv_ioda_pe
> iommu_group_put(pe->table_group.group);
> BUG_ON(pe->table_group.group);
> }
> - iommu_free_table(tbl, of_node_full_name(dev->dev.of_node));
> + iommu_tce_table_put(tbl);
> }
>
> static void pnv_ioda_release_vf_PE(struct pci_dev *pdev)
> @@ -2225,7 +2225,7 @@ static void pnv_pci_ioda1_setup_dma_pe(struct pnv_phb *phb,
> __free_pages(tce_mem, get_order(tce32_segsz * segs));
> if (tbl) {
> pnv_pci_unlink_table_and_group(tbl, &pe->table_group);
> - iommu_free_table(tbl, "pnv");
> + iommu_tce_table_put(tbl);
> }
> }
>
> @@ -2321,7 +2321,7 @@ static long pnv_pci_ioda2_create_table(struct iommu_table_group *table_group,
> bus_offset, page_shift, window_size,
> levels, tbl);
> if (ret) {
> - iommu_free_table(tbl, "pnv");
> + iommu_tce_table_put(tbl);
> return ret;
> }
>
> @@ -2365,7 +2365,7 @@ static long pnv_pci_ioda2_setup_default_config(struct pnv_ioda_pe *pe)
> if (rc) {
> pe_err(pe, "Failed to configure 32-bit TCE table, err %ld\n",
> rc);
> - iommu_free_table(tbl, "");
> + iommu_tce_table_put(tbl);
> return rc;
> }
>
> @@ -2453,7 +2453,7 @@ static void pnv_ioda2_take_ownership(struct iommu_table_group *table_group)
> pnv_pci_ioda2_unset_window(&pe->table_group, 0);
> if (pe->pbus)
> pnv_ioda_setup_bus_dma(pe, pe->pbus, false);
> - iommu_free_table(tbl, "pnv");
> + iommu_tce_table_put(tbl);
> }
>
> static void pnv_ioda2_release_ownership(struct iommu_table_group *table_group)
> @@ -3428,7 +3428,7 @@ static void pnv_pci_ioda1_release_pe_dma(struct pnv_ioda_pe *pe)
> }
>
> free_pages(tbl->it_base, get_order(tbl->it_size << 3));
> - iommu_free_table(tbl, "pnv");
> + iommu_tce_table_put(tbl);
> }
>
> static void pnv_pci_ioda2_release_pe_dma(struct pnv_ioda_pe *pe)
> @@ -3455,7 +3455,7 @@ static void pnv_pci_ioda2_release_pe_dma(struct pnv_ioda_pe *pe)
> }
>
> pnv_pci_ioda2_table_free_pages(tbl);
> - iommu_free_table(tbl, "pnv");
> + iommu_tce_table_put(tbl);
> }
>
> static void pnv_ioda_free_pe_seg(struct pnv_ioda_pe *pe,
> diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
> index eb835e977e33..204a829ff506 100644
> --- a/arch/powerpc/platforms/powernv/pci.c
> +++ b/arch/powerpc/platforms/powernv/pci.c
> @@ -767,6 +767,7 @@ struct iommu_table *pnv_pci_table_alloc(int nid)
>
> tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL, nid);
> INIT_LIST_HEAD_RCU(&tbl->it_group_list);
> + kref_init(&tbl->it_kref);
>
> return tbl;
> }
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 4d757eaa46bf..7ce5db209abf 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -74,6 +74,7 @@ static struct iommu_table_group *iommu_pseries_alloc_group(int node)
> goto fail_exit;
>
> INIT_LIST_HEAD_RCU(&tbl->it_group_list);
> + kref_init(&tbl->it_kref);
> tgl->table_group = table_group;
> list_add_rcu(&tgl->next, &tbl->it_group_list);
>
> @@ -115,7 +116,7 @@ static void iommu_pseries_free_group(struct iommu_table_group *table_group,
> BUG_ON(table_group->group);
> }
> #endif
> - iommu_free_table(tbl, node_name);
> + iommu_tce_table_put(tbl);
>
> kfree(table_group);
> }
> diff --git a/arch/powerpc/platforms/pseries/vio.c b/arch/powerpc/platforms/pseries/vio.c
> index 720493932486..28b09fd797ec 100644
> --- a/arch/powerpc/platforms/pseries/vio.c
> +++ b/arch/powerpc/platforms/pseries/vio.c
> @@ -1318,7 +1318,7 @@ static void vio_dev_release(struct device *dev)
> struct iommu_table *tbl = get_iommu_table_base(dev);
>
> if (tbl)
> - iommu_free_table(tbl, of_node_full_name(dev->of_node));
> + iommu_tce_table_put(tbl);
> of_node_put(dev->of_node);
> kfree(to_vio_dev(dev));
> }
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index fbec7348a7e5..8031d3a55a17 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -680,7 +680,7 @@ static void tce_iommu_free_table(struct tce_container *container,
> unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
>
> tce_iommu_userspace_view_free(tbl, container->mm);
> - iommu_free_table(tbl, "");
> + iommu_tce_table_put(tbl);
> decrement_locked_vm(container->mm, pages);
> }
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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next prev parent reply other threads:[~2017-03-22 0:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-17 5:09 [PATCH kernel v10 00/10] powerpc/kvm/vfio: Enable in-kernel acceleration Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 01/10] powerpc/mmu: Add real mode support for IOMMU preregistered memory Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 02/10] powerpc/powernv/iommu: Add real mode version of iommu_table_ops::exchange() Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 03/10] powerpc/iommu/vfio_spapr_tce: Cleanup iommu_table disposal Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 04/10] powerpc/vfio_spapr_tce: Add reference counting to iommu_table Alexey Kardashevskiy
2017-03-22 0:40 ` David Gibson [this message]
2017-03-17 5:09 ` [PATCH kernel v10 05/10] KVM: PPC: Reserve KVM_CAP_SPAPR_TCE_VFIO capability number Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 06/10] KVM: PPC: Enable IOMMU_API for KVM_BOOK3S_64 permanently Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 07/10] KVM: PPC: Pass kvm* to kvmppc_find_table() Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 08/10] KVM: PPC: Use preregistered memory API to access TCE list Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 09/10] KVM: PPC: iommu: Unify TCE checking Alexey Kardashevskiy
2017-03-17 5:09 ` [PATCH kernel v10 10/10] KVM: PPC: VFIO: Add in-kernel acceleration for VFIO Alexey Kardashevskiy
2017-03-21 19:11 ` Alex Williamson
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