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[PULL,20/56] pcihp: piix4: do not call acpi_pcihp_reset() when ACPI PCI hotplug is disabled

Message ID 20230130201810.11518-21-mst@redhat.com (mailing list archive)
State New, archived
Headers show
Series [PULL,01/56] shpc: disallow unplug when power indicator is blinking | expand

Commit Message

Michael S. Tsirkin Jan. 30, 2023, 8:19 p.m. UTC
From: Igor Mammedov <imammedo@redhat.com>

piix4_pm_reset() is calling acpi_pcihp_reset() when ACPI PCI hotplug
is disabled, which leads to assigning BSEL properties to bridges on path
       if (qbus_is_hotpluggable(BUS(bus))) {
          // above happens to be true by default (though it's SHPC hotplug handler)
          // set BSEL

At the moment the issue is masked by the fact that we use not only BSEL,
to decide if we should generated hoplug AML but also pcihp_bridge_en knob.
However the later patches will drop dependency on pcihp_bridge_en,
and use only BSEL exclusively to decide if hotplug AML for slots should be built,
which exposes issue.

We should not ever call acpi_pcihp_reset() if ACPI PCI hotplug is disabled,
make it so.

 * Q35 does the right thing (i.e. it calls acpi_pcihp_reset only when pcihp is enabled)
 * the issue also makes acpi_pcihp_update() logic run on SHPC enabled bridges,
   which seems to be harmless

Fixes: 3d7e78aa777 ("Introduce a new flag for i440fx to disable PCI hotplug on the root bus")
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Message-Id: <20230112140312.3096331-11-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
 hw/acpi/piix4.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
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diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index 2ab4930f11..724294b378 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -304,7 +304,9 @@  static void piix4_pm_reset(DeviceState *dev)
     acpi_update_sci(&s->ar, s->irq);
-    acpi_pcihp_reset(&s->acpi_pci_hotplug, !s->use_acpi_root_pci_hotplug);
+    if (s->use_acpi_hotplug_bridge || s->use_acpi_root_pci_hotplug) {
+        acpi_pcihp_reset(&s->acpi_pci_hotplug, !s->use_acpi_root_pci_hotplug);
+    }
 static void piix4_pm_powerdown_req(Notifier *n, void *opaque)