Hi,
On 02/06/2023 01:48, Vikram Garhwal wrote:
Rename iommu_dt_device_is_assigned() to iommu_dt_device_is_assigned_locked().
Remove static type so this can also be used by SMMU drivers to check if the
device is being used before removing.
Moving spin_lock to caller was done to prevent the concurrent access to
iommu_dt_device_is_assigned while doing add/remove/assign/deassign.
Can you explain if you are trying to resolve an existing bug, or this is
something that will be necessary in a follow-up patch?
Signed-off-by: Vikram Garhwal <vikram.garh...@amd.com>
---
Changes from v6:
Created a private header and moved iommu_dt_device_is_assigned() to header.
---
xen/drivers/passthrough/device_tree.c | 20 ++++++++++++++++----
xen/include/xen/iommu-private.h | 27 +++++++++++++++++++++++++++
2 files changed, 43 insertions(+), 4 deletions(-)
create mode 100644 xen/include/xen/iommu-private.h
diff --git a/xen/drivers/passthrough/device_tree.c
b/xen/drivers/passthrough/device_tree.c
index 1c32d7b50c..52e370db01 100644
--- a/xen/drivers/passthrough/device_tree.c
+++ b/xen/drivers/passthrough/device_tree.c
@@ -18,6 +18,7 @@
#include <xen/device_tree.h>
#include <xen/guest_access.h>
#include <xen/iommu.h>
+#include <xen/iommu-private.h>
#include <xen/lib.h>
#include <xen/sched.h>
#include <xsm/xsm.h>
@@ -83,16 +84,14 @@ fail:
return rc;
}
-static bool_t iommu_dt_device_is_assigned(const struct dt_device_node *dev)
+bool_t iommu_dt_device_is_assigned_locked(const struct dt_device_node *dev)
{
Please add an ASSERT() checking the lock is taken.
bool_t assigned = 0;
if ( !dt_device_is_protected(dev) )
return 0;
- spin_lock(&dtdevs_lock);
assigned = !list_empty(&dev->domain_list);
- spin_unlock(&dtdevs_lock);
return assigned;
}
@@ -213,27 +212,40 @@ int iommu_do_dt_domctl(struct xen_domctl *domctl, struct
domain *d,
if ( (d && d->is_dying) || domctl->u.assign_device.flags )
break;
+ spin_lock(&dtdevs_lock);
+
'dtdevs_lock' was intended to protect modification related to any IOMMU
change. But here...
ret = dt_find_node_by_gpath(domctl->u.assign_device.u.dt.path,
domctl->u.assign_device.u.dt.size,
&dev);
... you also include "dt_find_node_by_gpath". Can you explain why and
add a comment on top of 'dtdevs_lock' to explain what it is intended use?
if ( ret )
+ {
+ spin_unlock(&dtdevs_lock);
break;
+ }
ret = xsm_assign_dtdevice(XSM_HOOK, d, dt_node_full_name(dev));
if ( ret )
+ {
+ spin_unlock(&dtdevs_lock);
break;
+ }
if ( domctl->cmd == XEN_DOMCTL_test_assign_device )
{
- if ( iommu_dt_device_is_assigned(dev) )
+
+ if ( iommu_dt_device_is_assigned_locked(dev) )
{
printk(XENLOG_G_ERR "%s already assigned.\n",
dt_node_full_name(dev));
ret = -EINVAL;
}
+
+ spin_unlock(&dtdevs_lock);
break;
}
+ spin_unlock(&dtdevs_lock);
+
if ( d == dom_io )
return -EINVAL;
diff --git a/xen/include/xen/iommu-private.h b/xen/include/xen/iommu-private.h
new file mode 100644
index 0000000000..5615decaff
--- /dev/null
+++ b/xen/include/xen/iommu-private.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+ /*
+ * xen/iommu-private.h
+ *
+ *
+ * Copyright (C) 2023, Advanced Micro Devices, Inc. All Rights Reserved.
+ * Written by Vikram Garhwal <vikram.garh...@amd.com>
+ *
+ */
+#ifndef __XEN_IOMMU_PRIVATE_H__
+#define __XEN_IOMMU_PRIVATE_H__
+
+#ifdef CONFIG_HAS_DEVICE_TREE
+#include <xen/device_tree.h>
+bool_t iommu_dt_device_is_assigned_locked(const struct dt_device_node *dev);
+#endif
+
+#endif /* __XEN_IOMMU_PRIVATE_H__ */
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
Julien Grall
