linux-kernel - [PATCH v4 2/7] vhost-vdpa: reset vendor specific mapping to initial state in .release

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Message-Id: <1697880319-4937-3-git-send-email-si-wei.liu@oracle.com>
Date:   Sat, 21 Oct 2023 02:25:14 -0700
From:   Si-Wei Liu <si-wei.liu@...cle.com>
To:     jasowang@...hat.com, mst@...hat.com, eperezma@...hat.com,
        sgarzare@...hat.com, dtatulea@...dia.com
Cc:     virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/7] vhost-vdpa: reset vendor specific mapping to initial state in .release

Devices with on-chip IOMMU or vendor specific IOTLB implementation may
need to restore iotlb mapping to the initial or default state using the
.reset_map op, as it's desirable for some parent devices to not work
with DMA ops and maintain a simple IOMMU model with .reset_map. In
particular, device reset should not cause mapping to go away on such
IOTLB model, so persistent mapping is implied across reset. Before the
userspace process using vhost-vdpa is gone, give it a chance to reset
iotlb back to the initial state in vhost_vdpa_cleanup().

Signed-off-by: Si-Wei Liu <si-wei.liu@...cle.com>
Acked-by: Eugenio Pérez <eperezma@...hat.com>
---
 drivers/vhost/vdpa.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 851535f57b95..c6bfe9bdde42 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -131,6 +131,15 @@ static struct vhost_vdpa_as *vhost_vdpa_find_alloc_as(struct vhost_vdpa *v,
 	return vhost_vdpa_alloc_as(v, asid);
 }
 
+static void vhost_vdpa_reset_map(struct vhost_vdpa *v, u32 asid)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+
+	if (ops->reset_map)
+		ops->reset_map(vdpa, asid);
+}
+
 static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
 {
 	struct vhost_vdpa_as *as = asid_to_as(v, asid);
@@ -140,6 +149,14 @@ static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid)
 
 	hlist_del(&as->hash_link);
 	vhost_vdpa_iotlb_unmap(v, &as->iotlb, 0ULL, 0ULL - 1, asid);
+	/*
+	 * Devices with vendor specific IOMMU may need to restore
+	 * iotlb to the initial or default state, which cannot be
+	 * cleaned up in the all range unmap call above. Give them
+	 * a chance to clean up or reset the map to the desired
+	 * state.
+	 */
+	vhost_vdpa_reset_map(v, asid);
 	kfree(as);
 
 	return 0;
-- 
2.39.3