On 15.12.23 02:00, David Stevens wrote:
On Thu, Dec 14, 2023 at 6:47 PM David Hildenbrand <david@xxxxxxxxxx> wrote:
On 08.12.23 08:07, David Stevens wrote:
If a virtio_pci_device supports native PCI power management and has the
No_Soft_Reset bit set, then skip resetting and reinitializing the device
when suspending and restoring the device. This allows system-wide low
power states like s2idle to be used in systems with stateful virtio
devices that can't simply be re-initialized (e.g. virtio-fs).
Signed-off-by: David Stevens <stevensd@xxxxxxxxxxxx>
---
v1 -> v2:
- Check the No_Soft_Reset bit
drivers/virtio/virtio_pci_common.c | 34 +++++++++++++++++++++++++++++-
1 file changed, 33 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index c2524a7207cf..3a95ecaf12dc 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -492,8 +492,40 @@ static int virtio_pci_restore(struct device *dev)
return virtio_device_restore(&vp_dev->vdev);
}
+static bool vp_supports_pm_no_reset(struct device *dev)
+{
+ struct pci_dev *pci_dev = to_pci_dev(dev);
+ u16 pmcsr;
+
+ if (!pci_dev->pm_cap)
+ return false;
+
+ pci_read_config_word(pci_dev, pci_dev->pm_cap + PCI_PM_CTRL, &pmcsr);
+ if (PCI_POSSIBLE_ERROR(pmcsr)) {
+ dev_err(dev, "Unable to query pmcsr");
+ return false;
+ }
+
+ return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
+}
+
+static int virtio_pci_suspend(struct device *dev)
+{
+ return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
+}
+
+static int virtio_pci_resume(struct device *dev)
+{
+ return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
+}
+
static const struct dev_pm_ops virtio_pci_pm_ops = {
- SET_SYSTEM_SLEEP_PM_OPS(virtio_pci_freeze, virtio_pci_restore)
+ .suspend = virtio_pci_suspend,
+ .resume = virtio_pci_resume,
+ .freeze = virtio_pci_freeze,
+ .thaw = virtio_pci_restore,
+ .poweroff = virtio_pci_freeze,
+ .restore = virtio_pci_restore,
};
#endif
Am I correct with my assumption that this will make s2idle work with virtio-mem-pci as well?
Right now, all suspending is disabled, but really only s4/hibernate is problematic.
[root@vm-0 ~]# echo "s2idle" > /sys/power/mem_sleep
[root@vm-0 ~]# echo "mem" > /sys/power/state
[ 101.822991] PM: suspend entry (s2idle)
[ 101.828978] Filesystems sync: 0.004 seconds
[ 101.831618] Freezing user space processes
[ 101.834569] Freezing user space processes completed (elapsed 0.001 seconds)
[ 101.836915] OOM killer disabled.
[ 101.838072] Freezing remaining freezable tasks
[ 101.841054] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[ 101.843538] printk: Suspending console(s) (use no_console_suspend to debug)
[ 101.957676] virtio_mem virtio0: save/restore not supported.
[ 101.957683] virtio-pci 0000:00:02.0: PM: pci_pm_suspend(): virtio_pci_freeze+0x0/0x50 returns -1
[ 101.957702] virtio-pci 0000:00:02.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x170 returns -1
[ 101.957718] virtio-pci 0000:00:02.0: PM: failed to suspend async: error -1
QEMU's virtio-pci devices don't advertise no_soft_reset, so this patch
won't affect vanilla QEMU. But if you add PCI_PM_CTRL_NO_SOFT_RESET to
the capability, then it should work. I'm working with crosvm, which
doesn't have virtio-mem implemented, but this patch makes virtio-fs
work with no extra kernel changes.
Thanks for the explanation, makes sense to me.
--
Cheers,
David / dhildenb
