Re: [Xen-devel] [PATCH v2 10/12] xen/iommu: smmu: Check for duplicate stream IDs when registering master devices

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 16 Jan 2015, Julien Grall wrote:
> From: Andreas Herrmann <andreas.herrmann@xxxxxxxxxxx>
> 
> If DT information lists one stream ID twice for the master devices of
> an SMMU this can cause a multi match when stream ID matching is used.
> For stream ID indexing this might trigger an overwrite of an S2CR that
> is already in use.
> 
> So better check for duplicates when DT information is parsed.
> 
> Taken from the linux ML:
> http://lists.infradead.org/pipermail/linux-arm-kernel/2014-January/226099.html
> 
> Cc: Andreas Herrmann <herrmann.der.user@xxxxxxxxxxxxxx>
> Signed-off-by: Andreas Herrmann <andreas.herrmann@xxxxxxxxxxx>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>

Why didn't you just take a more recent version of the Linux smmu driver?


>  xen/drivers/passthrough/arm/smmu.c | 25 +++++++++++++++++++++++--
>  1 file changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/drivers/passthrough/arm/smmu.c 
> b/xen/drivers/passthrough/arm/smmu.c
> index 6cd47b7..bfc1069 100644
> --- a/xen/drivers/passthrough/arm/smmu.c
> +++ b/xen/drivers/passthrough/arm/smmu.c
> @@ -51,6 +51,9 @@
>  /* Maximum number of stream IDs assigned to a single device */
>  #define MAX_MASTER_STREAMIDS         MAX_PHANDLE_ARGS
>  
> +/* Maximum stream ID */
> +#define ARM_SMMU_MAX_STREAMID                (SZ_64K - 1)
> +
>  /* Maximum number of context banks per SMMU */
>  #define ARM_SMMU_MAX_CBS             128
>  
> @@ -519,7 +522,8 @@ static int insert_smmu_master(struct arm_smmu_device 
> *smmu,
>  
>  static int register_smmu_master(struct arm_smmu_device *smmu,
>                               struct device *dev,
> -                             struct of_phandle_args *masterspec)
> +                             struct of_phandle_args *masterspec,
> +                             unsigned long *smmu_sids)
>  {
>       int i;
>       struct arm_smmu_master *master;
> @@ -556,6 +560,12 @@ static int register_smmu_master(struct arm_smmu_device 
> *smmu,
>                               masterspec->np->name, smmu->num_mapping_groups);
>                       return -ERANGE;
>               }
> +
> +             if (test_and_set_bit(streamid, smmu_sids)) {
> +                     dev_err(dev, "duplicate stream ID (%d)\n", streamid);
> +                     return -EEXIST;
> +             }
> +
>               master->cfg.streamids[i] = streamid;
>       }
>       return insert_smmu_master(smmu, master);
> @@ -1977,6 +1987,7 @@ static int arm_smmu_device_dt_probe(struct 
> platform_device *pdev)
>       struct device *dev = &pdev->dev;
>       struct rb_node *node;
>       struct of_phandle_args masterspec;
> +     unsigned long *smmu_sids;
>       int num_irqs, i, err;
>  
>       smmu = devm_kzalloc(dev, sizeof(*smmu), GFP_KERNEL);
> @@ -2035,20 +2046,30 @@ static int arm_smmu_device_dt_probe(struct 
> platform_device *pdev)
>       if (err)
>               return err;
>  
> +     smmu_sids = kzalloc(BITS_TO_LONGS(ARM_SMMU_MAX_STREAMID) *
> +                     sizeof(long), GFP_KERNEL);
> +     if (!smmu_sids) {
> +             dev_err(dev,
> +                     "failed to allocate bitmap for stream ID tracking\n");
> +             return -ENOMEM;
> +     }
> +
>       i = 0;
>       smmu->masters = RB_ROOT;
>       while (!of_parse_phandle_with_args(dev->of_node, "mmu-masters",
>                                          "#stream-id-cells", i,
>                                          &masterspec)) {
> -             err = register_smmu_master(smmu, dev, &masterspec);
> +             err = register_smmu_master(smmu, dev, &masterspec, smmu_sids);
>               if (err) {
>                       dev_err(dev, "failed to add master %s\n",
>                               masterspec.np->name);
> +                     kfree(smmu_sids);
>                       goto out_put_masters;
>               }
>  
>               i++;
>       }
> +     kfree(smmu_sids);
>       dev_notice(dev, "registered %d master devices\n", i);
>  
>       parse_driver_options(smmu);
> -- 
> 2.1.4
> 

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