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[PATCH v10 04/13] Fix a gap where acpi_pcihp_find_hotplug_bus() returns
From: |
Ani Sinha |
Subject: |
[PATCH v10 04/13] Fix a gap where acpi_pcihp_find_hotplug_bus() returns a non-hotpluggable bus |
Date: |
Fri, 18 Sep 2020 14:11:02 +0530 |
When ACPI hotplug for the root bus is disabled, the bsel property for that
bus is not set. Please see the following commit:
3d7e78aa7777f ("Introduce a new flag for i440fx to disable PCI hotplug on the
root bus").
As a result, when acpi_pcihp_find_hotplug_bus() is called
with bsel set to 0, it may return the root bus. This can cause devices
attached to the root bus to get hot-unplugged if the user issues the following
set of commmands:
outl 0xae10 0
outl 0xae08 your_slot
Thanks to Julia for pointing this out here:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg734548.html
In this patch, we fix the issue in this function by checking if the bus which
is returned by the function is actually hotpluggable. If not, we simply return
NULL. This avoids the scenario where we were returning a non-hotpluggable bus.
Signed-off-by: Ani Sinha <ani@anisinha.ca>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
---
hw/acpi/pcihp.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index 39b1f74442..32ae8b2c0a 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -147,6 +147,21 @@ static PCIBus *acpi_pcihp_find_hotplug_bus(AcpiPciHpState
*s, int bsel)
if (!bsel && !find.bus) {
find.bus = s->root;
}
+
+ /*
+ * Check if find.bus is actually hotpluggable. If bsel is set to
+ * NULL for example on the root bus in order to make it
+ * non-hotpluggable, find.bus will match the root bus when bsel
+ * is 0. See acpi_pcihp_test_hotplug_bus() above. Since the
+ * bus is not hotpluggable however, we should not select the bus.
+ * Instead, we should set find.bus to NULL in that case. In the check
+ * below, we generalize this case for all buses, not just the root bus.
+ * The callers of this function check for a null return value and
+ * handle them appropriately.
+ */
+ if (find.bus && !qbus_is_hotpluggable(BUS(find.bus))) {
+ find.bus = NULL;
+ }
return find.bus;
}
--
2.17.1
- [PATCH v10 00/13] i440fx/acpi: addition of feature and bug fixes., Ani Sinha, 2020/09/18
- [PATCH v10 01/13] tests/acpi: mark addition of table DSDT.roothp for unit testing root pci hotplug, Ani Sinha, 2020/09/18
- [PATCH v10 02/13] tests/acpi: add new unit test to test hotplug off/on feature on the root pci bus, Ani Sinha, 2020/09/18
- [PATCH v10 03/13] tests/acpi: add a new ACPI table in order to test root pci hotplug on/off, Ani Sinha, 2020/09/18
- [PATCH v10 04/13] Fix a gap where acpi_pcihp_find_hotplug_bus() returns a non-hotpluggable bus,
Ani Sinha <=
- [PATCH v10 05/13] i440fx/acpi: do not add hotplug related amls for cold plugged bridges, Ani Sinha, 2020/09/18
- [PATCH v10 06/13] tests/acpi: list added acpi table binary file for pci bridge hotplug test, Ani Sinha, 2020/09/18
- [PATCH v10 07/13] tests/acpi: unit test for 'acpi-pci-hotplug-with-bridge-support' bridge flag, Ani Sinha, 2020/09/18
- [PATCH v10 08/13] tests/acpi: add newly added acpi DSDT table blob for pci bridge hotplug flag, Ani Sinha, 2020/09/18
- [PATCH v10 09/13] Add ACPI DSDT tables for q35 that are being updated by the next patch, Ani Sinha, 2020/09/18
- [PATCH v10 10/13] piix4: don't reserve hw resources when hotplug is off globally, Ani Sinha, 2020/09/18
- [PATCH v10 11/13] tests/acpi: update golden master DSDT binary table blobs for q35, Ani Sinha, 2020/09/18
- [PATCH v10 12/13] tests/acpi: unit test exercising global pci hotplug off for i440fx, Ani Sinha, 2020/09/18
- [PATCH v10 13/13] tests/acpi: add DSDT.hpbrroot DSDT table blob to test global i440fx hotplug, Ani Sinha, 2020/09/18