pcihp: reduce number of device check events
PIIX created a made-up value for the UP register since it was read by
guest 32 times for each interrupt.
There's no reason to do this for the new PCIHP: register is only read
once for each interrupt, so clean up code by making read act as an
interrupt acknowledgement: the new UP register clear on read.
In this way we cut down the number of bus rescans
by a factor of 32, and drop a bunch of code that's
now unused.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c
index 3fa3d7c..4345f5d 100644
--- a/hw/acpi/pcihp.c
+++ b/hw/acpi/pcihp.c
@@ -116,7 +116,6 @@
{
BusChild *kid, *next;
int slot = ffs(slots) - 1;
- bool slot_free = true;
PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel);
if (!bus) {
@@ -125,21 +124,17 @@
/* Mark request as complete */
s->acpi_pcihp_pci_status[bsel].down &= ~(1U << slot);
+ s->acpi_pcihp_pci_status[bsel].up &= ~(1U << slot);
QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) {
DeviceState *qdev = kid->child;
PCIDevice *dev = PCI_DEVICE(qdev);
if (PCI_SLOT(dev->devfn) == slot) {
- if (acpi_pcihp_pc_no_hotplug(s, dev)) {
- slot_free = false;
- } else {
+ if (!acpi_pcihp_pc_no_hotplug(s, dev)) {
object_unparent(OBJECT(qdev));
}
}
}
- if (slot_free) {
- s->acpi_pcihp_pci_status[bsel].device_present &= ~(1U << slot);
- }
}
static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel)
@@ -153,7 +148,6 @@
}
s->acpi_pcihp_pci_status[bsel].hotplug_enable = ~0;
- s->acpi_pcihp_pci_status[bsel].device_present = 0;
if (!bus) {
return;
@@ -166,8 +160,6 @@
if (acpi_pcihp_pc_no_hotplug(s, pdev)) {
s->acpi_pcihp_pci_status[bsel].hotplug_enable &= ~(1U << slot);
}
-
- s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot);
}
}
@@ -187,7 +179,7 @@
static void enable_device(AcpiPciHpState *s, unsigned bsel, int slot)
{
- s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot);
+ s->acpi_pcihp_pci_status[bsel].up |= (1U << slot);
}
static void disable_device(AcpiPciHpState *s, unsigned bsel, int slot)
@@ -208,7 +200,6 @@
* it is present on boot, no hotplug event is necessary. We do send an
* event when the device is disabled later. */
if (state == PCI_COLDPLUG_ENABLED) {
- s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot);
return 0;
}
@@ -233,10 +224,8 @@
switch (addr) {
case PCI_UP_BASE - PCI_HOTPLUG_ADDR:
- /* Manufacture an "up" value to cause a device check on any hotplug
- * slot with a device. Extra device checks are harmless. */
- val = s->acpi_pcihp_pci_status[bsel].device_present &
- s->acpi_pcihp_pci_status[bsel].hotplug_enable;
+ val = s->acpi_pcihp_pci_status[bsel].up;
+ s->acpi_pcihp_pci_status[bsel].up = 0;
ACPI_PCIHP_DPRINTF("pci_up_read %" PRIu32 "\n", val);
break;
case PCI_DOWN_BASE - PCI_HOTPLUG_ADDR:
