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Subject[PATCH] ACPI / PCI: Bail early in acpi_pci_add_bus() if there is no ACPI handle
Date
Hyper-V instances support PCI pass-through which is implemented through
PV pci-hyperv driver. When a device is passed through a new root PCI bus
is created in the guest. The bus sits on top of VMBus and has no
associated information in ACPI. acpi_pci_add_bus() in this case proceeds
all the way to acpi_evaluate_dsm() with reports

ACPI: \: failed to evaluate _DSM (0x1001)

While acpi_pci_slot_enumerate() and acpiphp_enumerate_slots() are protected
against ACPI_HANDLE() being NULL and do nothing acpi_evaluate_dsm() is not
and gives us the error. It seems the correct fix is to not do anything in
acpi_pci_add_bus() in such cases.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
drivers/pci/pci-acpi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index a8da543b3814..4708eb9df71b 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -624,7 +624,7 @@ void acpi_pci_add_bus(struct pci_bus *bus)
union acpi_object *obj;
struct pci_host_bridge *bridge;

- if (acpi_pci_disabled || !bus->bridge)
+ if (acpi_pci_disabled || !bus->bridge || !ACPI_HANDLE(bus->bridge))
return;

acpi_pci_slot_enumerate(bus);
--
2.13.5
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