motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-05 08:43:55 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

hw/pci: Basic support for PCI power management

Browse source 
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>
This commit is contained in:
Alex Williamson 2025-02-25 14:52:25 -07:00 • committed by Cédric Le Goater
parent 3f8f6ef701
commit 9461afd200
4 changed files with 99 additions and 2 deletions
Download patch file Download diff file Expand all files Collapse all files

2
hw/pci/trace-events
View file

@ -1,6 +1,8 @@
# See docs/devel/tracing.rst for syntax documentation.
# pci.c
pci_pm_bad_transition(const char *dev, uint32_t bus, uint32_t slot, uint32_t func, uint8_t old, uint8_t new) "%s %02x:%02x.%x REJECTED PM transition D%d->D%d"
pci_pm_transition(const char *dev, uint32_t bus, uint32_t slot, uint32_t func, uint8_t old, uint8_t new) "%s %02x:%02x.%x PM transition D%d->D%d"
pci_update_mappings_del(const char *dev, uint32_t bus, uint32_t slot, uint32_t func, int bar, uint64_t addr, uint64_t size) "%s %02x:%02x.%x %d,0x%"PRIx64"+0x%"PRIx64
pci_update_mappings_add(const char *dev, uint32_t bus, uint32_t slot, uint32_t func, int bar, uint64_t addr, uint64_t size) "%s %02x:%02x.%x %d,0x%"PRIx64"+0x%"PRIx64
pci_route_irq(int dev_irq, const char *dev_path, int parent_irq, const char *parent_path) "IRQ %d @%s -> IRQ %d @%s"