linux-kernel - [RFC PATCH 16/42] iommufd: Enable device feature IOPF during device attachment to KVM HWPT

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Message-Id: <20231202092311.14392-1-yan.y.zhao@intel.com>
Date:   Sat,  2 Dec 2023 17:23:11 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     alex.williamson@...hat.com, jgg@...dia.com, pbonzini@...hat.com,
        seanjc@...gle.com, joro@...tes.org, will@...nel.org,
        robin.murphy@....com, kevin.tian@...el.com,
        baolu.lu@...ux.intel.com, dwmw2@...radead.org, yi.l.liu@...el.com,
        Yan Zhao <yan.y.zhao@...el.com>
Subject: [RFC PATCH 16/42] iommufd: Enable device feature IOPF during device attachment to KVM HWPT

Enable device feature IOPF during device attachment to KVM HWPT and abort
the attachment if feature enabling is failed.

"pin" is not done by KVM HWPT. If VMM wants to create KVM HWPT, it must
know that all devices attached to this HWPT support IOPF so that pin-all
is skipped.

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 drivers/iommu/iommufd/device.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 83af6b7e2784b..4ea447e052ce1 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -381,10 +381,26 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 			goto err_unresv;
 		idev->igroup->hwpt = hwpt;
 	}
+	if (hwpt_is_kvm(hwpt)) {
+		/*
+		 * Feature IOPF requires ats is enabled which is true only
+		 * after device is attached to iommu domain.
+		 * So enable dev feature IOPF after iommu_attach_group().
+		 * -EBUSY will be returned if feature IOPF is already on.
+		 */
+		rc = iommu_dev_enable_feature(idev->dev, IOMMU_DEV_FEAT_IOPF);
+		if (rc && rc != -EBUSY)
+			goto err_detach;
+	}
 	refcount_inc(&hwpt->obj.users);
 	list_add_tail(&idev->group_item, &idev->igroup->device_list);
 	mutex_unlock(&idev->igroup->lock);
 	return 0;
+err_detach:
+	if (list_empty(&idev->igroup->device_list)) {
+		iommu_detach_group(hwpt->domain, idev->igroup->group);
+		idev->igroup->hwpt = NULL;
+	}
 err_unresv:
 	if (hwpt_is_paging(hwpt))
 		iopt_remove_reserved_iova(&to_hwpt_paging(hwpt)->ioas->iopt,
@@ -408,6 +424,8 @@ iommufd_hw_pagetable_detach(struct iommufd_device *idev)
 	if (hwpt_is_paging(hwpt))
 		iopt_remove_reserved_iova(&to_hwpt_paging(hwpt)->ioas->iopt,
 					  idev->dev);
+	if (hwpt_is_kvm(hwpt))
+		iommu_dev_disable_feature(idev->dev, IOMMU_DEV_FEAT_IOPF);
 	mutex_unlock(&idev->igroup->lock);
 
 	/* Caller must destroy hwpt */
-- 
2.17.1