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Message-ID: <b0403334-1b88-e75a-418d-71a78ef97c9c@intel.com>
Date: Sun, 31 Jul 2022 20:50:33 +0800
From: Yi Liu <yi.l.liu@...el.com>
To: Lu Baolu <baolu.lu@...ux.intel.com>,
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>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>
CC: Eric Auger <eric.auger@...hat.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
Zhangfei Gao <zhangfei.gao@...aro.org>,
Zhu Tony <tony.zhu@...el.com>, <iommu@...ts.linux.dev>,
<linux-kernel@...r.kernel.org>,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v10 10/12] iommu: Prepare IOMMU domain for IOPF
On 2022/7/5 13:07, Lu Baolu wrote:
> This adds some mechanisms around the iommu_domain so that the I/O page
> fault handling framework could route a page fault to the domain and
> call the fault handler from it.
>
> Add pointers to the page fault handler and its private data in struct
> iommu_domain. The fault handler will be called with the private data
> as a parameter once a page fault is routed to the domain. Any kernel
> component which owns an iommu domain could install handler and its
> private parameter so that the page fault could be further routed and
> handled.
>
> This also prepares the SVA implementation to be the first consumer of
> the per-domain page fault handling model. The I/O page fault handler
> for SVA is copied to the SVA file with mmget_not_zero() added before
> mmap_read_lock().
>
> Suggested-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>
> Tested-by: Tony Zhu <tony.zhu@...el.com>
> ---
> include/linux/iommu.h | 3 ++
> drivers/iommu/iommu-sva-lib.h | 8 +++++
> drivers/iommu/io-pgfault.c | 7 +++++
> drivers/iommu/iommu-sva-lib.c | 58 +++++++++++++++++++++++++++++++++++
> drivers/iommu/iommu.c | 4 +++
> 5 files changed, 80 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index ae0cfca064e6..47610f21d451 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -105,6 +105,9 @@ struct iommu_domain {
> unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
> struct iommu_domain_geometry geometry;
> struct iommu_dma_cookie *iova_cookie;
> + enum iommu_page_response_code (*iopf_handler)(struct iommu_fault *fault,
> + void *data);
> + void *fault_data;
> union {
> struct {
> iommu_fault_handler_t handler;
> diff --git a/drivers/iommu/iommu-sva-lib.h b/drivers/iommu/iommu-sva-lib.h
> index 8909ea1094e3..1b3ace4b5863 100644
> --- a/drivers/iommu/iommu-sva-lib.h
> +++ b/drivers/iommu/iommu-sva-lib.h
> @@ -26,6 +26,8 @@ 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);
> +enum iommu_page_response_code
> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data);
>
> #else /* CONFIG_IOMMU_SVA */
> static inline int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> @@ -63,5 +65,11 @@ static inline int iopf_queue_discard_partial(struct iopf_queue *queue)
> {
> return -ENODEV;
> }
> +
> +static inline enum iommu_page_response_code
> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
> +{
> + return IOMMU_PAGE_RESP_INVALID;
> +}
> #endif /* CONFIG_IOMMU_SVA */
> #endif /* _IOMMU_SVA_LIB_H */
> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
> index 1df8c1dcae77..aee9e033012f 100644
> --- a/drivers/iommu/io-pgfault.c
> +++ b/drivers/iommu/io-pgfault.c
> @@ -181,6 +181,13 @@ static void iopf_handle_group(struct work_struct *work)
> * request completes, outstanding faults will have been dealt with by the time
> * the PASID is freed.
> *
> + * Any valid page fault will be eventually routed to an iommu domain and the
> + * page fault handler installed there will get called. The users of this
> + * handling framework should guarantee that the iommu domain could only be
> + * freed after the device has stopped generating page faults (or the iommu
> + * hardware has been set to block the page faults) and the pending page faults
> + * have been flushed.
> + *
> * Return: 0 on success and <0 on error.
> */
> int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
> diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
> index 751366980232..536d34855c74 100644
> --- a/drivers/iommu/iommu-sva-lib.c
> +++ b/drivers/iommu/iommu-sva-lib.c
> @@ -167,3 +167,61 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> return domain->mm->pasid;
> }
> EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
> +
> +/*
> + * I/O page fault handler for SVA
> + */
> +enum iommu_page_response_code
> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
> +{
> + vm_fault_t ret;
> + struct vm_area_struct *vma;
> + struct mm_struct *mm = data;
> + unsigned int access_flags = 0;
> + unsigned int fault_flags = FAULT_FLAG_REMOTE;
> + struct iommu_fault_page_request *prm = &fault->prm;
> + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
> +
> + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
> + return status;
> +
> + if (IS_ERR_OR_NULL(mm) || !mmget_not_zero(mm))
is it possible to be ERR or NULL? The mm life circle should have been
guaranteed by the mmgrab() in iommu_sva_domain_alloc(). Perhaps coding
issue if it happens. :-)
> + return status;
> +
> + mmap_read_lock(mm);
> +
> + vma = find_extend_vma(mm, prm->addr);
> + if (!vma)
> + /* Unmapped area */
> + goto out_put_mm;
> +
> + if (prm->perm & IOMMU_FAULT_PERM_READ)
> + access_flags |= VM_READ;
> +
> + if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
> + access_flags |= VM_WRITE;
> + fault_flags |= FAULT_FLAG_WRITE;
> + }
> +
> + if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
> + access_flags |= VM_EXEC;
> + fault_flags |= FAULT_FLAG_INSTRUCTION;
> + }
> +
> + if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
> + fault_flags |= FAULT_FLAG_USER;
> +
> + if (access_flags & ~vma->vm_flags)
> + /* Access fault */
> + goto out_put_mm;
> +
> + ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
> + status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
> + IOMMU_PAGE_RESP_SUCCESS;
> +
> +out_put_mm:
> + mmap_read_unlock(mm);
> + mmput(mm);
> +
> + return status;
> +}
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index e1491eb3c7b6..c6e9c8e82771 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -29,6 +29,8 @@
> #include <trace/events/iommu.h>
> #include <linux/sched/mm.h>
>
> +#include "iommu-sva-lib.h"
> +
> static struct kset *iommu_group_kset;
> static DEFINE_IDA(iommu_group_ida);
>
> @@ -3199,6 +3201,8 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev,
> domain->type = IOMMU_DOMAIN_SVA;
> mmgrab(mm);
> domain->mm = mm;
> + domain->iopf_handler = iommu_sva_handle_iopf;
> + domain->fault_data = mm;
>
> return domain;
> }
--
Regards,
Yi Liu
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