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Message-ID: <20220329143848.2e763727@jacob-builder>
Date: Tue, 29 Mar 2022 14:38:48 -0700
From: Jacob Pan <jacob.jun.pan@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>
Cc: Joerg Roedel <joro@...tes.org>, Jason Gunthorpe <jgg@...dia.com>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
jacob.jun.pan@...el.com
Subject: Re: [PATCH RFC v2 03/11] iommu/sva: Add iommu_domain type for SVA
Hi BaoLu,
On Tue, 29 Mar 2022 13:37:52 +0800, Lu Baolu <baolu.lu@...ux.intel.com>
wrote:
> Add a new iommu domain type IOMMU_DOMAIN_SVA to represent an I/O page
> table which is shared from CPU host VA. Add some helpers to get and
> put an SVA domain and implement SVA domain life cycle management.
>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> ---
> include/linux/iommu.h | 7 +++
> drivers/iommu/iommu-sva-lib.h | 10 ++++
> drivers/iommu/iommu-sva-lib.c | 89 +++++++++++++++++++++++++++++++++++
> 3 files changed, 106 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 36f43af0af53..29c4c2edd706 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -42,6 +42,7 @@ struct notifier_block;
> struct iommu_sva;
> struct iommu_fault_event;
> struct iommu_dma_cookie;
> +struct iommu_sva_cookie;
>
> /* iommu fault flags */
> #define IOMMU_FAULT_READ 0x0
> @@ -64,6 +65,9 @@ struct iommu_domain_geometry {
> #define __IOMMU_DOMAIN_PT (1U << 2) /* Domain is identity mapped
> */ #define __IOMMU_DOMAIN_DMA_FQ (1U << 3) /* DMA-API uses
> flush queue */
> +#define __IOMMU_DOMAIN_SHARED (1U << 4) /* Page table shared
> from CPU */ +#define __IOMMU_DOMAIN_HOST_VA (1U << 5) /* Host
> CPU virtual address */ +
> /*
> * This are the possible domain-types
> *
> @@ -86,6 +90,8 @@ struct iommu_domain_geometry {
> #define IOMMU_DOMAIN_DMA_FQ (__IOMMU_DOMAIN_PAGING | \
> __IOMMU_DOMAIN_DMA_API | \
> __IOMMU_DOMAIN_DMA_FQ)
> +#define IOMMU_DOMAIN_SVA (__IOMMU_DOMAIN_SHARED | \
> + __IOMMU_DOMAIN_HOST_VA)
>
> struct iommu_domain {
> unsigned type;
> @@ -95,6 +101,7 @@ struct iommu_domain {
> void *handler_token;
> struct iommu_domain_geometry geometry;
> struct iommu_dma_cookie *iova_cookie;
> + struct iommu_sva_cookie *sva_cookie;
> };
>
> static inline bool iommu_is_dma_domain(struct iommu_domain *domain)
> diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
> index 8909ea1094e3..1a71218b07f5 100644
> --- a/drivers/iommu/iommu-sva-lib.h
> +++ b/drivers/iommu/iommu-sva-lib.h
> @@ -10,6 +10,7 @@
>
> int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t
> max); struct mm_struct *iommu_sva_find(ioasid_t pasid);
> +struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain);
>
> /* I/O Page fault */
> struct device;
> @@ -26,6 +27,8 @@ int iopf_queue_flush_dev(struct device *dev);
> struct iopf_queue *iopf_queue_alloc(const char *name);
> void iopf_queue_free(struct iopf_queue *queue);
> int iopf_queue_discard_partial(struct iopf_queue *queue);
> +bool iommu_sva_domain_get_user(struct iommu_domain *domain);
> +void iommu_sva_domain_put_user(struct iommu_domain *domain);
>
> #else /* CONFIG_IOMMU_SVA */
> static inline int iommu_queue_iopf(struct iommu_fault *fault, void
> *cookie) @@ -63,5 +66,12 @@ static inline int
> iopf_queue_discard_partial(struct iopf_queue *queue) {
> return -ENODEV;
> }
> +
> +static inline bool iommu_sva_domain_get_user(struct iommu_domain *domain)
> +{
> + return false;
> +}
> +
> +static inline void iommu_sva_domain_put_user(struct iommu_domain
> *domain) { } #endif /* CONFIG_IOMMU_SVA */
> #endif /* _IOMMU_SVA_LIB_H */
> diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
> index 106506143896..78820be23f15 100644
> --- a/drivers/iommu/iommu-sva-lib.c
> +++ b/drivers/iommu/iommu-sva-lib.c
> @@ -3,12 +3,21 @@
> * Helpers for IOMMU drivers implementing SVA
> */
> #include <linux/mutex.h>
> +#include <linux/iommu.h>
> +#include <linux/slab.h>
> #include <linux/sched/mm.h>
>
> #include "iommu-sva-lib.h"
>
> static DEFINE_MUTEX(iommu_sva_lock);
> static DECLARE_IOASID_SET(iommu_sva_pasid);
> +static DEFINE_XARRAY_ALLOC(sva_domain_array);
> +
> +struct iommu_sva_cookie {
> + struct mm_struct *mm;
> + ioasid_t pasid;
> + refcount_t users;
> +};
>
> /**
> * iommu_sva_alloc_pasid - Allocate a PASID for the mm
> @@ -69,3 +78,83 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid)
> return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
> }
> EXPORT_SYMBOL_GPL(iommu_sva_find);
> +
> +static struct iommu_domain *
> +iommu_sva_alloc_domain(struct device *dev, struct mm_struct *mm)
> +{
> + struct bus_type *bus = dev->bus;
> + struct iommu_sva_cookie *cookie;
> + struct iommu_domain *domain;
> + void *curr;
> +
> + if (!bus || !bus->iommu_ops)
> + return NULL;
> +
> + cookie = kzalloc(sizeof(*cookie), GFP_KERNEL);
> + if (!cookie)
> + return NULL;
> +
> + domain = bus->iommu_ops->domain_alloc(IOMMU_DOMAIN_SVA);
> + if (!domain)
> + goto err_domain_alloc;
> +
> + cookie->mm = mm;
> + cookie->pasid = mm->pasid;
How do you manage the mm life cycle? do you require caller take mm reference?
Or this should be limited to the current mm?
> + refcount_set(&cookie->users, 1);
> + domain->type = IOMMU_DOMAIN_SVA;
> + domain->sva_cookie = cookie;
> + curr = xa_store(&sva_domain_array, mm->pasid, domain,
> GFP_KERNEL);
> + if (xa_err(curr))
> + goto err_xa_store;
> +
> + return domain;
> +err_xa_store:
> + domain->ops->free(domain);
> +err_domain_alloc:
> + kfree(cookie);
> + return NULL;
> +}
> +
> +static void iommu_sva_free_domain(struct iommu_domain *domain)
> +{
> + xa_erase(&sva_domain_array, domain->sva_cookie->pasid);
> + kfree(domain->sva_cookie);
> + domain->ops->free(domain);
> +}
> +
> +bool iommu_sva_domain_get_user(struct iommu_domain *domain)
> +{
> + struct iommu_sva_cookie *cookie = domain->sva_cookie;
> +
> + return refcount_inc_not_zero(&cookie->users);
> +}
> +
> +void iommu_sva_domain_put_user(struct iommu_domain *domain)
> +{
> + struct iommu_sva_cookie *cookie = domain->sva_cookie;
> +
> + if (refcount_dec_and_test(&cookie->users))
> + iommu_sva_free_domain(domain);
> +}
> +
> +static __maybe_unused struct iommu_domain *
> +iommu_sva_get_domain(struct device *dev, struct mm_struct *mm)
> +{
> + struct iommu_domain *domain;
> + ioasid_t pasid = mm->pasid;
> +
> + if (pasid == INVALID_IOASID)
> + return NULL;
> +
> + domain = xa_load(&sva_domain_array, pasid);
> + if (!domain)
> + return iommu_sva_alloc_domain(dev, mm);
> + iommu_sva_domain_get_user(domain);
> +
> + return domain;
> +}
> +
> +struct mm_struct *iommu_sva_domain_mm(struct iommu_domain *domain)
> +{
> + return domain->sva_cookie->mm;
> +}
Thanks,
Jacob
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