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SubjectRe: [PATCH v1 7/9] iommu/tegra: gart: Provide single domain and group for all devices
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On 08.05.2018 21:16, Dmitry Osipenko wrote:
> GART aperture is shared by all devices, hence there is a single IOMMU
> domain and group shared by these devices. Allocation of a group per
> device only wastes resources and allowance of having more than one domain
> is simply wrong because IOMMU mappings made by the users of "different"
> domains will stomp on each other.
>
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
> drivers/iommu/tegra-gart.c | 107 +++++++++----------------------------
> 1 file changed, 24 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
> index 5b2d27620350..ebc105c201bd 100644
> --- a/drivers/iommu/tegra-gart.c
> +++ b/drivers/iommu/tegra-gart.c
> @@ -19,7 +19,6 @@
>
> #include <linux/io.h>
> #include <linux/iommu.h>
> -#include <linux/list.h>
> #include <linux/module.h>
> #include <linux/of_device.h>
> #include <linux/slab.h>
> @@ -44,22 +43,17 @@
> #define GART_PAGE_MASK \
> (~(GART_PAGE_SIZE - 1) & ~GART_ENTRY_PHYS_ADDR_VALID)
>
> -struct gart_client {
> - struct device *dev;
> - struct list_head list;
> -};
> -
> struct gart_device {
> void __iomem *regs;
> u32 *savedata;
> u32 page_count; /* total remappable size */
> dma_addr_t iovmm_base; /* offset to vmm_area */
> spinlock_t pte_lock; /* for pagetable */
> - struct list_head client;
> - spinlock_t client_lock; /* for client list */
> struct device *dev;
>
> struct iommu_device iommu; /* IOMMU Core handle */
> + struct iommu_group *group; /* Common IOMMU group */
> + struct gart_domain *domain; /* Unique IOMMU domain */
>
> struct tegra_mc_gart_handle mc_gart_handle;
> };
> @@ -169,81 +163,31 @@ static inline bool gart_iova_range_valid(struct gart_device *gart,
> static int gart_iommu_attach_dev(struct iommu_domain *domain,
> struct device *dev)
> {
> - struct gart_domain *gart_domain = to_gart_domain(domain);
> - struct gart_device *gart = gart_domain->gart;
> - struct gart_client *client, *c;
> - int err = 0;
> -
> - client = devm_kzalloc(gart->dev, sizeof(*c), GFP_KERNEL);
> - if (!client)
> - return -ENOMEM;
> - client->dev = dev;
> -
> - spin_lock(&gart->client_lock);
> - list_for_each_entry(c, &gart->client, list) {
> - if (c->dev == dev) {
> - dev_err(gart->dev,
> - "%s is already attached\n", dev_name(dev));
> - err = -EINVAL;
> - goto fail;
> - }
> - }
> - list_add(&client->list, &gart->client);
> - spin_unlock(&gart->client_lock);
> - dev_dbg(gart->dev, "Attached %s\n", dev_name(dev));
> return 0;
> -
> -fail:
> - devm_kfree(gart->dev, client);
> - spin_unlock(&gart->client_lock);
> - return err;
> }
>
> static void gart_iommu_detach_dev(struct iommu_domain *domain,
> struct device *dev)
> {
> - struct gart_domain *gart_domain = to_gart_domain(domain);
> - struct gart_device *gart = gart_domain->gart;
> - struct gart_client *c;
> -
> - spin_lock(&gart->client_lock);
> -
> - list_for_each_entry(c, &gart->client, list) {
> - if (c->dev == dev) {
> - list_del(&c->list);
> - devm_kfree(gart->dev, c);
> - dev_dbg(gart->dev, "Detached %s\n", dev_name(dev));
> - goto out;
> - }
> - }
> - dev_err(gart->dev, "Couldn't find\n");
> -out:
> - spin_unlock(&gart->client_lock);
> }
>
> static struct iommu_domain *gart_iommu_domain_alloc(unsigned type)
> {
> - struct gart_domain *gart_domain;
> - struct gart_device *gart;
> -
> - if (type != IOMMU_DOMAIN_UNMANAGED)
> - return NULL;
> + struct gart_device *gart = gart_handle;
>
> - gart = gart_handle;
> - if (!gart)
> + if (type != IOMMU_DOMAIN_UNMANAGED || gart->domain)
> return NULL;
>
> - gart_domain = kzalloc(sizeof(*gart_domain), GFP_KERNEL);
> - if (!gart_domain)
> - return NULL;
> -
> - gart_domain->gart = gart;
> - gart_domain->domain.geometry.aperture_start = gart->iovmm_base;
> - gart_domain->domain.geometry.aperture_end = gart->iovmm_base +
> + gart->domain = kzalloc(sizeof(*gart->domain), GFP_KERNEL);
> + if (gart->domain) {
> + gart->domain->domain.geometry.aperture_start = gart->iovmm_base;
> + gart->domain->domain.geometry.aperture_end = gart->iovmm_base +
> gart->page_count * GART_PAGE_SIZE - 1;
> - gart_domain->domain.geometry.force_aperture = true;
> + gart->domain->domain.geometry.force_aperture = true;
> + gart->domain->gart = gart;
> + }
>
> - return &gart_domain->domain;
> + return &gart->domain->domain;
> }

I've missed a NULL-check and locking here, this will be fixed in v2. For now
I'll wait for the review comments (please review).

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