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The memory and IO BARs for devices are only accessible in the D0 power state. In other power states the PCI spec defines that the device responds to TLPs and messages with an Unsupported Request response. To approximate this behavior, consider the BARs as unmapped when the device is not in the D0 power state. This makes the BARs inaccessible and has the additional bonus for vfio-pci that we don't attempt to DMA map BARs for devices in a non-D0 power state. To support this, an interface is added for devices to register the PM capability, which allows central tracking to enforce valid transitions and unmap BARs in non-D0 states. NB. We currently have device models (eepro100 and pcie_pci_bridge) that register a PM capability but do not set wmask to enable writes to the power state field. In order to maintain migration compatibility, this new helper does not manage the wmask to enable guest writes to initiate a power state change. The contents and write access of the PM capability are still managed by the caller. Cc: Michael S. Tsirkin <mst@redhat.com> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Eric Auger <eric.auger@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Link: https://lore.kernel.org/qemu-devel/20250225215237.3314011-2-alex.williamson@redhat.com Signed-off-by: Cédric Le Goater <clg@redhat.com> |
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| block | ||
| chardev | ||
| crypto | ||
| disas | ||
| exec | ||
| fpu | ||
| gdbstub | ||
| hw | ||
| io | ||
| libdecnumber | ||
| migration | ||
| monitor | ||
| net | ||
| qapi | ||
| qemu | ||
| qobject | ||
| qom | ||
| scsi | ||
| semihosting | ||
| standard-headers | ||
| system | ||
| tcg | ||
| ui | ||
| user | ||
| elf.h | ||
| glib-compat.h | ||
| qemu-io.h | ||
| qemu-main.h | ||