Re: [PATCH RFC v1 09/11] iommu/virtio: Implement sva bind/unbind calls

From: Jean-Philippe Brucker
Date: Tue Sep 21 2021 - 12:09:55 EST

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On Fri, Apr 23, 2021 at 03:21:45PM +0530, Vivek Gautam wrote:
> SVA bind and unbind implementations will allow to prepare translation
> context with CPU page tables that can be programmed into host iommu
> hardware to realize shared address space utilization between the CPU
> and virtualized devices using virtio-iommu.
>
> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxx>
> ---
> drivers/iommu/virtio-iommu.c | 199 +++++++++++++++++++++++++++++-
> include/uapi/linux/virtio_iommu.h | 2 +
> 2 files changed, 199 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/virtio-iommu.c b/drivers/iommu/virtio-iommu.c
> index 250c137a211b..08f1294baeab 100644
> --- a/drivers/iommu/virtio-iommu.c
> +++ b/drivers/iommu/virtio-iommu.c
> @@ -14,6 +14,9 @@
> #include <linux/interval_tree.h>
> #include <linux/iommu.h>
> #include <linux/io-pgtable.h>
> +#include <linux/mm.h>
> +#include <linux/mmu_context.h>
> +#include <linux/mmu_notifier.h>
> #include <linux/module.h>
> #include <linux/of_iommu.h>
> #include <linux/of_platform.h>
> @@ -28,6 +31,7 @@
> #include <uapi/linux/virtio_iommu.h>
> #include "iommu-pasid-table.h"
> #include "iommu-sva-lib.h"
> +#include "io-pgtable-arm.h"

Is this used here?

>
> #define MSI_IOVA_BASE 0x8000000
> #define MSI_IOVA_LENGTH 0x100000
> @@ -41,6 +45,7 @@ DEFINE_XARRAY_ALLOC1(viommu_asid_xa);
>
> static DEFINE_MUTEX(sva_lock);
> static DEFINE_MUTEX(iopf_lock);
> +static DEFINE_MUTEX(viommu_asid_lock);
>
> struct viommu_dev_pri_work {
> struct work_struct work;
> @@ -88,10 +93,22 @@ struct viommu_mapping {
> struct viommu_mm {
> int pasid;
> u64 archid;
> + struct viommu_sva_bond *bond;
> struct io_pgtable_ops *ops;
> struct viommu_domain *domain;
> };
>
> +struct viommu_sva_bond {
> + struct iommu_sva sva;
> + struct mm_struct *mm;
> + struct iommu_psdtable_mmu_notifier *viommu_mn;
> + struct list_head list;
> + refcount_t refs;
> +};
> +
> +#define sva_to_viommu_bond(handle) \
> + container_of(handle, struct viommu_sva_bond, sva)
> +
> struct viommu_domain {
> struct iommu_domain domain;
> struct viommu_dev *viommu;
> @@ -136,6 +153,7 @@ struct viommu_endpoint {
> bool pri_supported;
> bool sva_enabled;
> bool iopf_enabled;
> + struct list_head bonds;
> };
>
> struct viommu_ep_entry {
> @@ -1423,14 +1441,15 @@ static int viommu_attach_pasid_table(struct viommu_endpoint *vdev,
>
> pst_cfg->iommu_dev = viommu->dev->parent;
>
> + mutex_lock(&viommu_asid_lock);
> /* Prepare PASID tables info to allocate a new table */
> ret = viommu_prepare_pst(vdev, pst_cfg, fmt);
> if (ret)
> - return ret;
> + goto err_out_unlock;
>
> ret = iommu_psdtable_alloc(tbl, pst_cfg);
> if (ret)
> - return ret;
> + goto err_out_unlock;
>
> pst_cfg->iommu_dev = viommu->dev->parent;
> pst_cfg->fmt = PASID_TABLE_ARM_SMMU_V3;
> @@ -1452,6 +1471,7 @@ static int viommu_attach_pasid_table(struct viommu_endpoint *vdev,
> if (ret)
> goto err_free_ops;
> }
> + mutex_unlock(&viommu_asid_lock);
> } else {
> /* TODO: otherwise, check for compatibility with vdev. */
> return -ENOSYS;
> @@ -1467,6 +1487,8 @@ static int viommu_attach_pasid_table(struct viommu_endpoint *vdev,
> err_free_psdtable:
> iommu_psdtable_free(tbl, &tbl->cfg);
>
> +err_out_unlock:
> + mutex_unlock(&viommu_asid_lock);
> return ret;
> }
>
> @@ -1706,6 +1728,7 @@ static struct iommu_device *viommu_probe_device(struct device *dev)
> vdev->dev = dev;
> vdev->viommu = viommu;
> INIT_LIST_HEAD(&vdev->resv_regions);
> + INIT_LIST_HEAD(&vdev->bonds);
> dev_iommu_priv_set(dev, vdev);
>
> if (viommu->probe_size) {
> @@ -1755,6 +1778,175 @@ static int viommu_of_xlate(struct device *dev, struct of_phandle_args *args)
> return iommu_fwspec_add_ids(dev, args->args, 1);
> }
>
> +static u32 viommu_sva_get_pasid(struct iommu_sva *handle)
> +{
> + struct viommu_sva_bond *bond = sva_to_viommu_bond(handle);
> +
> + return bond->mm->pasid;
> +}
> +
> +static void viommu_mmu_notifier_free(struct mmu_notifier *mn)
> +{
> + kfree(mn_to_pstiommu(mn));
> +}
> +
> +static struct mmu_notifier_ops viommu_mmu_notifier_ops = {
> + .free_notifier = viommu_mmu_notifier_free,

.invalidate_range and .release will be needed as well, to keep up to date
with changes to the address space

> +};
> +
> +/* Allocate or get existing MMU notifier for this {domain, mm} pair */
> +static struct iommu_psdtable_mmu_notifier *
> +viommu_mmu_notifier_get(struct viommu_domain *vdomain, struct mm_struct *mm,
> + u32 asid_bits)
> +{
> + int ret;
> + struct iommu_psdtable_mmu_notifier *viommu_mn;
> + struct iommu_pasid_table *tbl = vdomain->pasid_tbl;
> +
> + list_for_each_entry(viommu_mn, &tbl->mmu_notifiers, list) {
> + if (viommu_mn->mn.mm == mm) {
> + refcount_inc(&viommu_mn->refs);
> + return viommu_mn;
> + }
> + }
> +
> + mutex_lock(&viommu_asid_lock);
> + viommu_mn = iommu_psdtable_alloc_shared(tbl, mm, &viommu_asid_xa,
> + asid_bits);
> + mutex_unlock(&viommu_asid_lock);
> + if (IS_ERR(viommu_mn))
> + return ERR_CAST(viommu_mn);
> +
> + refcount_set(&viommu_mn->refs, 1);
> + viommu_mn->cookie = vdomain;
> + viommu_mn->mn.ops = &viommu_mmu_notifier_ops;
> +
> + ret = mmu_notifier_register(&viommu_mn->mn, mm);
> + if (ret)
> + goto err_free_cd;
> +
> + ret = iommu_psdtable_write(tbl, &tbl->cfg, mm->pasid,
> + viommu_mn->vendor.cd);
> + if (ret)
> + goto err_put_notifier;
> +
> + list_add(&viommu_mn->list, &tbl->mmu_notifiers);
> + return viommu_mn;
> +
> +err_put_notifier:
> + /* Frees viommu_mn */
> + mmu_notifier_put(&viommu_mn->mn);
> +err_free_cd:
> + iommu_psdtable_free_shared(tbl, &viommu_asid_xa, viommu_mn->vendor.cd);
> + return ERR_PTR(ret);
> +}
> +
> +static void
> +viommu_mmu_notifier_put(struct iommu_psdtable_mmu_notifier *viommu_mn)
> +{
> + struct mm_struct *mm = viommu_mn->mn.mm;
> + struct viommu_domain *vdomain = viommu_mn->cookie;
> + struct iommu_pasid_table *tbl = vdomain->pasid_tbl;
> + u16 asid = viommu_mn->vendor.cd->asid;
> +
> + if (!refcount_dec_and_test(&viommu_mn->refs))
> + return;
> +
> + list_del(&viommu_mn->list);
> + iommu_psdtable_write(tbl, &tbl->cfg, mm->pasid, NULL);
> +
> + /*
> + * If we went through clear(), we've already invalidated, and no
> + * new TLB entry can have been formed.
> + */
> + if (!viommu_mn->cleared)
> + iommu_psdtable_flush_tlb(tbl, vdomain, asid);
> +
> + /* Frees smmu_mn */
> + mmu_notifier_put(&viommu_mn->mn);
> + iommu_psdtable_free_shared(tbl, &viommu_asid_xa, viommu_mn->vendor.cd);
> +}
> +
> +static struct iommu_sva *
> +__viommu_sva_bind(struct device *dev, struct mm_struct *mm)
> +{
> + int ret;
> + struct viommu_sva_bond *bond;
> + struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> + struct viommu_domain *vdomain = to_viommu_domain(domain);
> + struct viommu_endpoint *vdev = dev_iommu_priv_get(dev);
> + struct virtio_iommu_probe_table_format *desc = vdev->pgtf;
> +
> + if (!vdev || !vdev->sva_enabled)
> + return ERR_PTR(-ENODEV);
> +
> + /* If bind() was already called for this {dev, mm} pair, reuse it. */
> + list_for_each_entry(bond, &vdev->bonds, list) {
> + if (bond->mm == mm) {
> + refcount_inc(&bond->refs);
> + return &bond->sva;
> + }
> + }
> +
> + bond = kzalloc(sizeof(*bond), GFP_KERNEL);
> + if (!bond)
> + return ERR_PTR(-ENOMEM);
> +
> + /* Allocate a PASID for this mm if necessary */
> + ret = iommu_sva_alloc_pasid(mm, 1, (1U << vdev->pasid_bits) - 1);
> + if (ret)
> + goto err_free_bond;
> +
> + bond->mm = mm;
> + bond->sva.dev = dev;
> + refcount_set(&bond->refs, 1);
> +
> + bond->viommu_mn = viommu_mmu_notifier_get(vdomain, mm, desc->asid_bits);
> + if (IS_ERR(bond->viommu_mn)) {
> + ret = PTR_ERR(bond->viommu_mn);
> + goto err_free_pasid;
> + }
> +
> + list_add(&bond->list, &vdev->bonds);
> + return &bond->sva;
> +
> +err_free_pasid:
> + iommu_sva_free_pasid(mm);
> +err_free_bond:
> + kfree(bond);
> + return ERR_PTR(ret);
> +}
> +
> +/* closely follows arm_smmu_sva_bind() */
> +static struct iommu_sva *viommu_sva_bind(struct device *dev,
> + struct mm_struct *mm, void *drvdata)
> +{
> + struct iommu_sva *handle;
> +
> + mutex_lock(&sva_lock);
> + handle = __viommu_sva_bind(dev, mm);
> + mutex_unlock(&sva_lock);
> + return handle;
> +}
> +
> +void viommu_sva_unbind(struct iommu_sva *handle)
> +{
> + struct viommu_sva_bond *bond = sva_to_viommu_bond(handle);
> + struct viommu_endpoint *vdev = dev_iommu_priv_get(handle->dev);
> +
> + if (vdev->pri_supported)
> + iopf_queue_flush_dev(handle->dev);
> +
> + mutex_lock(&sva_lock);
> + if (refcount_dec_and_test(&bond->refs)) {
> + list_del(&bond->list);
> + viommu_mmu_notifier_put(bond->viommu_mn);
> + iommu_sva_free_pasid(bond->mm);
> + kfree(bond);
> + }
> + mutex_unlock(&sva_lock);
> +}
> +
> static bool viommu_endpoint_iopf_supported(struct viommu_endpoint *vdev)
> {
> /* TODO: support Stall model later */
> @@ -1960,6 +2152,9 @@ static struct iommu_ops viommu_ops = {
> .dev_feat_enabled = viommu_dev_feature_enabled,
> .dev_enable_feat = viommu_dev_enable_feature,
> .dev_disable_feat = viommu_dev_disable_feature,
> + .sva_bind = viommu_sva_bind,
> + .sva_unbind = viommu_sva_unbind,
> + .sva_get_pasid = viommu_sva_get_pasid,
> };
>
> static int viommu_init_vqs(struct viommu_dev *viommu)
> diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
> index 88a3db493108..c12d9b6a7243 100644
> --- a/include/uapi/linux/virtio_iommu.h
> +++ b/include/uapi/linux/virtio_iommu.h
> @@ -122,6 +122,8 @@ struct virtio_iommu_req_attach_pst_arm {
> #define VIRTIO_IOMMU_PGTF_ARM_HPD0 (1ULL << 41)
> #define VIRTIO_IOMMU_PGTF_ARM_EPD1 (1 << 23)
>
> +#define VIRTIO_IOMMU_PGTF_ARM_IPS_SHIFT 32
> +#define VIRTIO_IOMMU_PGTF_ARM_IPS_MASK 0x7

Probably not the right place for this change

Thanks,
Jean

> #define VIRTIO_IOMMU_PGTF_ARM_TG0_SHIFT 14
> #define VIRTIO_IOMMU_PGTF_ARM_TG0_MASK 0x3
> #define VIRTIO_IOMMU_PGTF_ARM_SH0_SHIFT 12
> --
> 2.17.1
>

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