Commit 5a2223ca authored by Michael S. Tsirkin's avatar Michael S. Tsirkin
Browse files

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: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 2b2449f7

hw/acpi/pcihp.c

+5 −16
Original line number Diff line number Diff line
@@ -116,7 +116,6 @@ static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slo 
{

    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 @@ static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slo 


    /* 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 @@ static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel) 
    }



    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 @@ static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel) 
        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 @@ void acpi_pcihp_reset(AcpiPciHpState *s) 


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 @@ int acpi_pcihp_device_hotplug(AcpiPciHpState *s, PCIDevice *dev, 
     * 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 @@ static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size) 


    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:

include/hw/acpi/pcihp.h

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ 
#include "hw/pci/pci.h" /* for PCIHotplugState */



typedef struct AcpiPciHpPciStatus {

    uint32_t up; /* deprecated, maintained for migration compatibility */

    uint32_t up;

    uint32_t down;

    uint32_t hotplug_enable;

    uint32_t device_present;