Hi Oleksandr,
On 17/11/2021 06:56, Oleksandr Andrushchenko wrote:
Hi, Julien!
On 16.11.21 20:48, Julien Grall wrote:
Hi Oleksander,
On 05/11/2021 06:33, Oleksandr Andrushchenko wrote:
From: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
If a PCI host bridge device is present in the device tree, but is
disabled, then its PCI host bridge driver was not instantiated.
This results in the failure of the pci_get_host_bridge_segment()
and the following panic during Xen start:
(XEN) Device tree generation failed (-22).
(XEN)
(XEN) ****************************************
(XEN) Panic on CPU 0:
(XEN) Could not set up DOM0 guest OS
(XEN) ****************************************
Fix this by adding "linux,pci-domain" property for all device tree nodes
which have "pci" device type, so we know which segments will be used by
the guest for which bridges.
Fixes: 4cfab4425d39 ("xen/arm: Add linux,pci-domain property for hwdom if not
available.")
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushche...@epam.com>
---
New in v6
---
xen/arch/arm/domain_build.c | 15 ++++++++++++++-
xen/arch/arm/pci/pci-host-common.c | 2 +-
xen/include/asm-arm/pci.h | 8 ++++++++
3 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 491f5e2c316e..f7fcb1400c19 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -753,9 +753,22 @@ static int __init write_properties(struct domain *d,
struct kernel_info *kinfo,
{
uint16_t segment;
+ /*
+ * The node doesn't have "linux,pci-domain" property and it is
+ * possible that:
+ * - Xen only has drivers for a part of the host bridges
+ * - some host bridges are disabled
+ * Make sure we insert the correct "linux,pci-domain" property
+ * in any case, so we know which segments will be used
+ * by Linux for which bridges.
The check above will check the node type is "pci". AFAICT, this would also cover PCI
devices. I am not aware of any issue to add "linux,pci-domain" for them. However, this
feels a bit odd.
From my understanding, a PCI device would always be described as a child of the
hostbridges. So I would rework the 'if' to also check if the parent type is not
"pci".
We may have "bridge -> bridge -> device" topology as well.
Do you have an example of Device-Tree?
So, I prefer to have the check as it is.
I don't really like the idea to spuriously add "linux,pci-domain" to PCI
DT node. But if there are no other solution, then this should at least
be mentionned in the commit message and code.
[...]
Yes, this sounds reasonable, I will add this change and print an error message
so it is
easier to understand what Xen doesn't like (it took me a while to debug and
understand
why I have "(XEN) Device tree generation failed (-22).")
Sounds good to me. The current error is indeed confusing.
Cheers,
--
Julien Grall
