| Message ID | 20240516100330.1433265-2-xin.wang2@amd.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Remaining patches for dynamic node programming using overlay dtbo | expand |
Hi Henry, On 16/05/2024 11:03, Henry Wang wrote: > If CONFIG_DEBUG=y, below assertion will be triggered: > (XEN) Assertion 'rw_is_locked(&dt_host_lock)' failed at drivers/passthrough/device_tree.c:146 > (XEN) ----[ Xen-4.19-unstable arm64 debug=y Not tainted ]---- > [...] > (XEN) Xen call trace: > (XEN) [<00000a0000257418>] iommu_remove_dt_device+0x8c/0xd4 (PC) > (XEN) [<00000a00002573a0>] iommu_remove_dt_device+0x14/0xd4 (LR) > (XEN) [<00000a000020797c>] dt-overlay.c#remove_node_resources+0x8c/0x90 > (XEN) [<00000a0000207f14>] dt-overlay.c#remove_nodes+0x524/0x648 > (XEN) [<00000a0000208460>] dt_overlay_sysctl+0x428/0xc68 > (XEN) [<00000a00002707f8>] arch_do_sysctl+0x1c/0x2c > (XEN) [<00000a0000230b40>] do_sysctl+0x96c/0x9ec > (XEN) [<00000a0000271e08>] traps.c#do_trap_hypercall+0x1e8/0x288 > (XEN) [<00000a0000273490>] do_trap_guest_sync+0x448/0x63c > (XEN) [<00000a000025c480>] entry.o#guest_sync_slowpath+0xa8/0xd8 > (XEN) > (XEN) > (XEN) **************************************** > (XEN) Panic on CPU 0: > (XEN) Assertion 'rw_is_locked(&dt_host_lock)' failed at drivers/passthrough/device_tree.c:146 > (XEN) **************************************** > > This is because iommu_remove_dt_device() is called without taking the > dt_host_lock. dt_host_lock is meant to ensure that the DT node will not > disappear behind back. So fix the issue by taking the lock as soon as > getting hold of overlay_node. > > Similar issue will be observed in adding the dtbo: > (XEN) Assertion 'system_state < SYS_STATE_active || rw_is_locked(&dt_host_lock)' > failed at xen-source/xen/drivers/passthrough/device_tree.c:192 > (XEN) ----[ Xen-4.19-unstable arm64 debug=y Not tainted ]---- > [...] > (XEN) Xen call trace: > (XEN) [<00000a00002594f4>] iommu_add_dt_device+0x7c/0x17c (PC) > (XEN) [<00000a0000259494>] iommu_add_dt_device+0x1c/0x17c (LR) > (XEN) [<00000a0000267db4>] handle_device+0x68/0x1e8 > (XEN) [<00000a0000208ba8>] dt_overlay_sysctl+0x9d4/0xb84 > (XEN) [<00000a000027342c>] arch_do_sysctl+0x24/0x38 > (XEN) [<00000a0000231ac8>] do_sysctl+0x9ac/0xa34 > (XEN) [<00000a0000274b70>] traps.c#do_trap_hypercall+0x230/0x2dc > (XEN) [<00000a0000276330>] do_trap_guest_sync+0x478/0x688 > (XEN) [<00000a000025e480>] entry.o#guest_sync_slowpath+0xa8/0xd8 > > This is because the lock is released too early. So fix the issue by > releasing the lock after handle_device(). > > Fixes: 7e5c4a8b86f1 ("xen/arm: Implement device tree node removal functionalities") > Signed-off-by: Henry Wang <xin.wang2@amd.com> Reviewed-by: Julien Grall <jgrall@amazon.com> Cheers,
diff --git a/xen/common/dt-overlay.c b/xen/common/dt-overlay.c index 1b197381f6..9cece79067 100644 --- a/xen/common/dt-overlay.c +++ b/xen/common/dt-overlay.c @@ -429,18 +429,24 @@ static int remove_nodes(const struct overlay_track *tracker) if ( overlay_node == NULL ) return -EINVAL; + write_lock(&dt_host_lock); + rc = remove_descendant_nodes_resources(overlay_node); if ( rc ) + { + write_unlock(&dt_host_lock); return rc; + } rc = remove_node_resources(overlay_node); if ( rc ) + { + write_unlock(&dt_host_lock); return rc; + } dt_dprintk("Removing node: %s\n", overlay_node->full_name); - write_lock(&dt_host_lock); - rc = dt_overlay_remove_node(overlay_node); if ( rc ) { @@ -604,8 +610,6 @@ static long add_nodes(struct overlay_track *tr, char **nodes_full_path) return rc; } - write_unlock(&dt_host_lock); - prev_node->allnext = next_node; overlay_node = dt_find_node_by_path(overlay_node->full_name); @@ -619,6 +623,7 @@ static long add_nodes(struct overlay_track *tr, char **nodes_full_path) rc = handle_device(hardware_domain, overlay_node, p2m_mmio_direct_c, tr->iomem_ranges, tr->irq_ranges); + write_unlock(&dt_host_lock); if ( rc ) { printk(XENLOG_ERR "Adding IRQ and IOMMU failed\n");
If CONFIG_DEBUG=y, below assertion will be triggered: (XEN) Assertion 'rw_is_locked(&dt_host_lock)' failed at drivers/passthrough/device_tree.c:146 (XEN) ----[ Xen-4.19-unstable arm64 debug=y Not tainted ]---- [...] (XEN) Xen call trace: (XEN) [<00000a0000257418>] iommu_remove_dt_device+0x8c/0xd4 (PC) (XEN) [<00000a00002573a0>] iommu_remove_dt_device+0x14/0xd4 (LR) (XEN) [<00000a000020797c>] dt-overlay.c#remove_node_resources+0x8c/0x90 (XEN) [<00000a0000207f14>] dt-overlay.c#remove_nodes+0x524/0x648 (XEN) [<00000a0000208460>] dt_overlay_sysctl+0x428/0xc68 (XEN) [<00000a00002707f8>] arch_do_sysctl+0x1c/0x2c (XEN) [<00000a0000230b40>] do_sysctl+0x96c/0x9ec (XEN) [<00000a0000271e08>] traps.c#do_trap_hypercall+0x1e8/0x288 (XEN) [<00000a0000273490>] do_trap_guest_sync+0x448/0x63c (XEN) [<00000a000025c480>] entry.o#guest_sync_slowpath+0xa8/0xd8 (XEN) (XEN) (XEN) **************************************** (XEN) Panic on CPU 0: (XEN) Assertion 'rw_is_locked(&dt_host_lock)' failed at drivers/passthrough/device_tree.c:146 (XEN) **************************************** This is because iommu_remove_dt_device() is called without taking the dt_host_lock. dt_host_lock is meant to ensure that the DT node will not disappear behind back. So fix the issue by taking the lock as soon as getting hold of overlay_node. Similar issue will be observed in adding the dtbo: (XEN) Assertion 'system_state < SYS_STATE_active || rw_is_locked(&dt_host_lock)' failed at xen-source/xen/drivers/passthrough/device_tree.c:192 (XEN) ----[ Xen-4.19-unstable arm64 debug=y Not tainted ]---- [...] (XEN) Xen call trace: (XEN) [<00000a00002594f4>] iommu_add_dt_device+0x7c/0x17c (PC) (XEN) [<00000a0000259494>] iommu_add_dt_device+0x1c/0x17c (LR) (XEN) [<00000a0000267db4>] handle_device+0x68/0x1e8 (XEN) [<00000a0000208ba8>] dt_overlay_sysctl+0x9d4/0xb84 (XEN) [<00000a000027342c>] arch_do_sysctl+0x24/0x38 (XEN) [<00000a0000231ac8>] do_sysctl+0x9ac/0xa34 (XEN) [<00000a0000274b70>] traps.c#do_trap_hypercall+0x230/0x2dc (XEN) [<00000a0000276330>] do_trap_guest_sync+0x478/0x688 (XEN) [<00000a000025e480>] entry.o#guest_sync_slowpath+0xa8/0xd8 This is because the lock is released too early. So fix the issue by releasing the lock after handle_device(). Fixes: 7e5c4a8b86f1 ("xen/arm: Implement device tree node removal functionalities") Signed-off-by: Henry Wang <xin.wang2@amd.com> --- v2: - Take the lock as soon as getting hold of overlay_node. Also release the lock after handle_device() when adding dtbo. v1.1: - Move the unlock position before the check of rc. --- xen/common/dt-overlay.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)