[PATCH v3 6/8] iommu/arm-smmu: Add impl hook for inherit boot mappings
Robin Murphy
robin.murphy at arm.com
Fri Sep 11 13:13:01 EDT 2020
On 2020-09-04 16:55, Bjorn Andersson wrote:
> Add a new operation to allow platform implementations to inherit any
> stream mappings from the boot loader.
Is there a reason we need an explicit step for this? The aim of the
cfg_probe hook is that the SMMU software state should all be set up by
then, and you can mess about with it however you like before
arm_smmu_reset() actually commits anything to hardware. I would have
thought you could permanently steal a context bank, configure it as your
bypass hole, read out the previous SME configuration and tweak
smmu->smrs and smmu->s2crs appropriately all together "invisibly" at
that point. If that can't work, I'm very curious as to what I've overlooked.
Robin.
> Signed-off-by: Bjorn Andersson <bjorn.andersson at linaro.org>
> ---
>
> Changes since v2:
> - New patch/interface
>
> drivers/iommu/arm/arm-smmu/arm-smmu.c | 11 ++++++-----
> drivers/iommu/arm/arm-smmu/arm-smmu.h | 6 ++++++
> 2 files changed, 12 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.c b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> index eb5c6ca5c138..4c4d302cd747 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.c
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.c
> @@ -85,11 +85,6 @@ static inline void arm_smmu_rpm_put(struct arm_smmu_device *smmu)
> pm_runtime_put_autosuspend(smmu->dev);
> }
>
> -static struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
> -{
> - return container_of(dom, struct arm_smmu_domain, domain);
> -}
> -
> static struct platform_driver arm_smmu_driver;
> static struct iommu_ops arm_smmu_ops;
>
> @@ -2188,6 +2183,12 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
> if (err)
> return err;
>
> + if (smmu->impl->inherit_mappings) {
> + err = smmu->impl->inherit_mappings(smmu);
> + if (err)
> + return err;
> + }
> +
> if (smmu->version == ARM_SMMU_V2) {
> if (smmu->num_context_banks > smmu->num_context_irqs) {
> dev_err(dev,
> diff --git a/drivers/iommu/arm/arm-smmu/arm-smmu.h b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> index 235d9a3a6ab6..f58164976e74 100644
> --- a/drivers/iommu/arm/arm-smmu/arm-smmu.h
> +++ b/drivers/iommu/arm/arm-smmu/arm-smmu.h
> @@ -378,6 +378,11 @@ struct arm_smmu_domain {
> struct iommu_domain domain;
> };
>
> +static inline struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
> +{
> + return container_of(dom, struct arm_smmu_domain, domain);
> +}
> +
> struct arm_smmu_master_cfg {
> struct arm_smmu_device *smmu;
> s16 smendx[];
> @@ -442,6 +447,7 @@ struct arm_smmu_impl {
> int (*alloc_context_bank)(struct arm_smmu_domain *smmu_domain,
> struct arm_smmu_device *smmu,
> struct device *dev, int start);
> + int (*inherit_mappings)(struct arm_smmu_device *smmu);
> };
>
> #define INVALID_SMENDX -1
>
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