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Date: Wed, 1 Mar 2023 18:03:17 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Jacob Pan <jacob.jun.pan@...ux.intel.com>,
LKML <linux-kernel@...r.kernel.org>, iommu@...ts.linux.dev,
Jason Gunthorpe <jgg@...dia.com>,
Lu Baolu <baolu.lu@...ux.intel.com>,
Joerg Roedel <joro@...tes.org>, dmaengine@...r.kernel.org,
vkoul@...nel.org
Cc: Robin Murphy <robin.murphy@....com>, Will Deacon <will@...nel.org>,
David Woodhouse <dwmw2@...radead.org>,
Raj Ashok <ashok.raj@...el.com>,
"Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>,
"Yu, Fenghua" <fenghua.yu@...el.com>,
Tony Luck <tony.luck@...el.com>,
"Zanussi, Tom" <tom.zanussi@...el.com>
Subject: Re: [PATCH 4/4] dmaengine/idxd: Re-enable kernel workqueue under DMA
API
On 3/1/23 5:59 PM, Jacob Pan wrote:
> Kernel workqueues were disabled due to flawed use of kernel VA and SVA
> API. Now That we have the support for attaching PASID to the device's
> default domain and the ability to reserve global PASIDs from SVA APIs,
> we can re-enable the kernel work queues and use them under DMA API.
>
> We also use non-privileged access for in-kernel DMA to be consistent
> with the IOMMU settings. Consequently, interrupt for user privilege is
> enabled for work completion IRQs.
>
> Link:https://lore.kernel.org/linux-iommu/20210511194726.GP1002214@nvidia.com/
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> ---
> drivers/dma/idxd/device.c | 30 +++++--------------------
> drivers/dma/idxd/init.c | 47 +++++++++++++++++++++++++++++++++++----
> drivers/dma/idxd/sysfs.c | 7 ------
> 3 files changed, 48 insertions(+), 36 deletions(-)
>
> diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
> index 125652a8bb29..96faf4d3445e 100644
> --- a/drivers/dma/idxd/device.c
> +++ b/drivers/dma/idxd/device.c
> @@ -299,21 +299,6 @@ void idxd_wqs_unmap_portal(struct idxd_device *idxd)
> }
> }
>
> -static void __idxd_wq_set_priv_locked(struct idxd_wq *wq, int priv)
> -{
> - struct idxd_device *idxd = wq->idxd;
> - union wqcfg wqcfg;
> - unsigned int offset;
> -
> - offset = WQCFG_OFFSET(idxd, wq->id, WQCFG_PRIVL_IDX);
> - spin_lock(&idxd->dev_lock);
> - wqcfg.bits[WQCFG_PRIVL_IDX] = ioread32(idxd->reg_base + offset);
> - wqcfg.priv = priv;
> - wq->wqcfg->bits[WQCFG_PRIVL_IDX] = wqcfg.bits[WQCFG_PRIVL_IDX];
> - iowrite32(wqcfg.bits[WQCFG_PRIVL_IDX], idxd->reg_base + offset);
> - spin_unlock(&idxd->dev_lock);
> -}
> -
> static void __idxd_wq_set_pasid_locked(struct idxd_wq *wq, int pasid)
> {
> struct idxd_device *idxd = wq->idxd;
> @@ -1324,15 +1309,14 @@ int drv_enable_wq(struct idxd_wq *wq)
> }
>
> /*
> - * In the event that the WQ is configurable for pasid and priv bits.
> - * For kernel wq, the driver should setup the pasid, pasid_en, and priv bit.
> - * However, for non-kernel wq, the driver should only set the pasid_en bit for
> - * shared wq. A dedicated wq that is not 'kernel' type will configure pasid and
> + * In the event that the WQ is configurable for pasid, the driver
> + * should setup the pasid, pasid_en bit. This is true for both kernel
> + * and user shared workqueues. There is no need to setup priv bit in
> + * that in-kernel DMA will also do user privileged requests.
> + * A dedicated wq that is not 'kernel' type will configure pasid and
> * pasid_en later on so there is no need to setup.
> */
> if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags)) {
> - int priv = 0;
> -
> if (wq_pasid_enabled(wq)) {
> if (is_idxd_wq_kernel(wq) || wq_shared(wq)) {
> u32 pasid = wq_dedicated(wq) ? idxd->pasid : 0;
> @@ -1340,10 +1324,6 @@ int drv_enable_wq(struct idxd_wq *wq)
> __idxd_wq_set_pasid_locked(wq, pasid);
> }
> }
> -
> - if (is_idxd_wq_kernel(wq))
> - priv = 1;
> - __idxd_wq_set_priv_locked(wq, priv);
> }
>
> rc = 0;
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index f30eef701970..dadc908318aa 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -501,14 +501,52 @@ static struct idxd_device *idxd_alloc(struct pci_dev *pdev, struct idxd_driver_d
>
> static int idxd_enable_system_pasid(struct idxd_device *idxd)
> {
> - return -EOPNOTSUPP;
> + struct pci_dev *pdev = idxd->pdev;
> + struct device *dev = &pdev->dev;
> + struct iommu_domain *domain;
> + union gencfg_reg gencfg;
> + ioasid_t pasid;
> + int ret;
> +
> + domain = iommu_get_domain_for_dev(dev);
> + if (!domain || domain->type == IOMMU_DOMAIN_BLOCKED)
> + return -EPERM;
> +
> + pasid = iommu_sva_reserve_pasid(1, dev->iommu->max_pasids);
> + if (pasid == IOMMU_PASID_INVALID)
> + return -ENOSPC;
> +
> + ret = iommu_attach_device_pasid(domain, dev, pasid);
> + if (ret) {
> + dev_err(dev, "failed to attach device pasid %d, domain type %d",
> + pasid, domain->type);
> + iommu_sva_unreserve_pasid(pasid);
> + return ret;
> + }
> +
> + /* Since we set user privilege for kernel DMA, enable completion IRQ */
> + gencfg.bits = ioread32(idxd->reg_base + IDXD_GENCFG_OFFSET);
> + gencfg.user_int_en = 1;
> + iowrite32(gencfg.bits, idxd->reg_base + IDXD_GENCFG_OFFSET);
> + idxd->pasid = pasid;
> +
> + return ret;
> }
>
> static void idxd_disable_system_pasid(struct idxd_device *idxd)
> {
> + struct pci_dev *pdev = idxd->pdev;
> + struct device *dev = &pdev->dev;
> + struct iommu_domain *domain;
> +
> + domain = iommu_get_domain_for_dev(dev);
> + if (!domain || domain->type == IOMMU_DOMAIN_BLOCKED)
> + return;
>
> - iommu_sva_unbind_device(idxd->sva);
> + iommu_detach_device_pasid(domain, dev, idxd->pasid);
> + iommu_sva_unreserve_pasid(idxd->pasid);
> idxd->sva = NULL;
> + idxd->pasid = IOMMU_PASID_INVALID;
> }
>
> static int idxd_probe(struct idxd_device *idxd)
> @@ -530,8 +568,9 @@ static int idxd_probe(struct idxd_device *idxd)
> } else {
> set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
>
> - if (idxd_enable_system_pasid(idxd))
> - dev_warn(dev, "No in-kernel DMA with PASID.\n");
> + rc = idxd_enable_system_pasid(idxd);
> + if (rc)
> + dev_warn(dev, "No in-kernel DMA with PASID. %d\n", rc);
> else
> set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
> }
> diff --git a/drivers/dma/idxd/sysfs.c b/drivers/dma/idxd/sysfs.c
> index 3229dfc78650..09f5c3f2a992 100644
> --- a/drivers/dma/idxd/sysfs.c
> +++ b/drivers/dma/idxd/sysfs.c
> @@ -944,13 +944,6 @@ static ssize_t wq_name_store(struct device *dev,
> if (strlen(buf) > WQ_NAME_SIZE || strlen(buf) == 0)
> return -EINVAL;
>
> - /*
> - * This is temporarily placed here until we have SVM support for
> - * dmaengine.
> - */
> - if (wq->type == IDXD_WQT_KERNEL && device_pasid_enabled(wq->idxd))
> - return -EOPNOTSUPP;
> -
> input = kstrndup(buf, count, GFP_KERNEL);
> if (!input)
> return -ENOMEM;
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