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pci: implement power state

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This allows to power off pci devices.  In "off" state the devices will
not be visible.  No pci config space access, no pci bar access, no dma.

Default state is "on", so this patch (alone) should not change behavior.

Use case:  Allows hotplug controllers implement slot power.  Hotplug
controllers doing so should set the inital power state for devices in
the ->plug callback.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-Id: <20211111130859.1171890-2-kraxel@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Gerd Hoffmann 2021-11-11 14:08:54 +01:00 • committed by Michael S. Tsirkin
parent c829540401
commit 23786d1344
3 changed files with 29 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

6
hw/pci/pci_host.c
View file

@ -74,7 +74,8 @@ void pci_host_config_write_common(PCIDevice *pci_dev, uint32_t addr,
/* non-zero functions are only exposed when function 0 is present,
* allowing direct removal of unexposed functions.
*/
if (pci_dev->qdev.hotplugged && !pci_get_function_0(pci_dev)) {
if ((pci_dev->qdev.hotplugged && !pci_get_function_0(pci_dev)) ||
!pci_dev->has_power) {
return;
}
@ -97,7 +98,8 @@ uint32_t pci_host_config_read_common(PCIDevice *pci_dev, uint32_t addr,
/* non-zero functions are only exposed when function 0 is present,
* allowing direct removal of unexposed functions.
*/
if (pci_dev->qdev.hotplugged && !pci_get_function_0(pci_dev)) {
if ((pci_dev->qdev.hotplugged && !pci_get_function_0(pci_dev)) ||
!pci_dev->has_power) {
return ~0x0;
}