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Message-ID: <3356d18f-d1ce-4995-2b95-16938df1b7d6@arm.com>
Date: Thu, 30 Mar 2023 16:09:03 +0100
From: Robin Murphy <robin.murphy@....com>
To: Steven Price <steven.price@....com>,
Heiko Stuebner <heiko@...ech.de>,
Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...pe.ca>
Cc: Will Deacon <will@...nel.org>, iommu@...ts.linux.dev,
linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
linux-rockchip@...ts.infradead.org,
John Keeping <john@...anate.com>,
Jason Gunthorpe <jgg@...dia.com>
Subject: Re: [PATCH v3] iommu/rockchip: Add missing set_platform_dma_ops
callback
On 2023-03-30 15:46, Steven Price wrote:
> Similar to exynos, we need a set_platform_dma_ops() callback for proper
> operation on ARM 32 bit after recent changes in the IOMMU framework
> (detach ops removal). But also the use of a NULL domain is confusing.
>
> Rework the code to have a singleton rk_identity_domain which is assigned
> to domain when using an identity mapping rather than "detaching". This
> makes the code easier to reason about.
Really this is adding complete support for IOMMU_DOMAIN_IDENTITY in
general, which will also be visible on arm64. The part then using it to
bodge a pseudo-default-domain for Arm seems more incidental ;)
> Signed-off-by: Steven Price <steven.price@....com>
> Reviewed-by: Jason Gunthorpe <jgg@...dia.com>
> ---
> Changes since v2[1]:
>
> * Fixed suspend/resume handlers to check against rk_identity_domain
> rather than NULL (thanks John).
>
> [1] https://lore.kernel.org/r/20230324111127.221640-1-steven.price%40arm.com
>
> drivers/iommu/rockchip-iommu.c | 56 +++++++++++++++++++++++++---------
> 1 file changed, 42 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
> index f30db22ea5d7..4f97af471671 100644
> --- a/drivers/iommu/rockchip-iommu.c
> +++ b/drivers/iommu/rockchip-iommu.c
> @@ -124,6 +124,7 @@ struct rk_iommudata {
>
> static struct device *dma_dev;
> static const struct rk_iommu_ops *rk_ops;
> +static struct iommu_domain rk_identity_domain;
>
> static inline void rk_table_flush(struct rk_iommu_domain *dom, dma_addr_t dma,
> unsigned int count)
> @@ -646,7 +647,7 @@ static irqreturn_t rk_iommu_irq(int irq, void *dev_id)
> * Ignore the return code, though, since we always zap cache
> * and clear the page fault anyway.
> */
> - if (iommu->domain)
> + if (iommu->domain != &rk_identity_domain)
> report_iommu_fault(iommu->domain, iommu->dev, iova,
> flags);
> else
> @@ -980,26 +981,27 @@ static int rk_iommu_enable(struct rk_iommu *iommu)
> return ret;
> }
>
> -static void rk_iommu_detach_device(struct iommu_domain *domain,
> - struct device *dev)
> +static int rk_iommu_identity_attach(struct iommu_domain *identity_domain,
> + struct device *dev)
> {
> struct rk_iommu *iommu;
> - struct rk_iommu_domain *rk_domain = to_rk_domain(domain);
> + struct rk_iommu_domain *rk_domain;
> unsigned long flags;
> int ret;
>
> /* Allow 'virtual devices' (eg drm) to detach from domain */
> iommu = rk_iommu_from_dev(dev);
> if (!iommu)
> - return;
> + return -ENODEV;
> +
> + rk_domain = to_rk_domain(iommu->domain);
>
> dev_dbg(dev, "Detaching from iommu domain\n");
>
> - /* iommu already detached */
> - if (iommu->domain != domain)
> - return;
> + if (iommu->domain == identity_domain)
> + return 0;
>
> - iommu->domain = NULL;
> + iommu->domain = identity_domain;
>
> spin_lock_irqsave(&rk_domain->iommus_lock, flags);
> list_del_init(&iommu->node);
> @@ -1011,7 +1013,25 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
> rk_iommu_disable(iommu);
> pm_runtime_put(iommu->dev);
> }
> +
> + return 0;
> +}
> +
> +static struct iommu_domain_ops rk_identity_ops = {
> + .attach_dev = rk_iommu_identity_attach,
Since it's going to behave like a regular identity domain and be treated
as one, it needs to support .free as well.
Thanks,
Robin.
> +};
> +
> +static struct iommu_domain rk_identity_domain = {
> + .type = IOMMU_DOMAIN_IDENTITY,
> + .ops = &rk_identity_ops,
> +};
> +
> +#ifdef CONFIG_ARM
> +static void rk_iommu_set_platform_dma(struct device *dev)
> +{
> + WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));
> }
> +#endif
>
> static int rk_iommu_attach_device(struct iommu_domain *domain,
> struct device *dev)
> @@ -1035,8 +1055,9 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
> if (iommu->domain == domain)
> return 0;
>
> - if (iommu->domain)
> - rk_iommu_detach_device(iommu->domain, dev);
> + ret = rk_iommu_identity_attach(&rk_identity_domain, dev);
> + if (ret)
> + return ret;
>
> iommu->domain = domain;
>
> @@ -1050,7 +1071,7 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
>
> ret = rk_iommu_enable(iommu);
> if (ret)
> - rk_iommu_detach_device(iommu->domain, dev);
> + WARN_ON(rk_iommu_identity_attach(&rk_identity_domain, dev));
>
> pm_runtime_put(iommu->dev);
>
> @@ -1061,6 +1082,9 @@ static struct iommu_domain *rk_iommu_domain_alloc(unsigned type)
> {
> struct rk_iommu_domain *rk_domain;
>
> + if (type == IOMMU_DOMAIN_IDENTITY)
> + return &rk_identity_domain;
> +
> if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
> return NULL;
>
> @@ -1176,6 +1200,7 @@ static int rk_iommu_of_xlate(struct device *dev,
> iommu_dev = of_find_device_by_node(args->np);
>
> data->iommu = platform_get_drvdata(iommu_dev);
> + data->iommu->domain = &rk_identity_domain;
> dev_iommu_priv_set(dev, data);
>
> platform_device_put(iommu_dev);
> @@ -1188,6 +1213,9 @@ static const struct iommu_ops rk_iommu_ops = {
> .probe_device = rk_iommu_probe_device,
> .release_device = rk_iommu_release_device,
> .device_group = rk_iommu_device_group,
> +#ifdef CONFIG_ARM
> + .set_platform_dma_ops = rk_iommu_set_platform_dma,
> +#endif
> .pgsize_bitmap = RK_IOMMU_PGSIZE_BITMAP,
> .of_xlate = rk_iommu_of_xlate,
> .default_domain_ops = &(const struct iommu_domain_ops) {
> @@ -1343,7 +1371,7 @@ static int __maybe_unused rk_iommu_suspend(struct device *dev)
> {
> struct rk_iommu *iommu = dev_get_drvdata(dev);
>
> - if (!iommu->domain)
> + if (iommu->domain == &rk_identity_domain)
> return 0;
>
> rk_iommu_disable(iommu);
> @@ -1354,7 +1382,7 @@ static int __maybe_unused rk_iommu_resume(struct device *dev)
> {
> struct rk_iommu *iommu = dev_get_drvdata(dev);
>
> - if (!iommu->domain)
> + if (iommu->domain == &rk_identity_domain)
> return 0;
>
> return rk_iommu_enable(iommu);
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