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Message-ID: <9fb51bfc-576a-4c7b-92c2-c161e7f08ae7@redhat.com> Date: Thu, 14 Dec 2023 10:47:50 +0100 From: David Hildenbrand <david@...hat.com> To: David Stevens <stevensd@...omium.org>, "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com> Cc: virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] virtio: Add support for no-reset virtio PCI PM 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@...omium.org> > --- > 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@...0 ~]# echo "s2idle" > /sys/power/mem_sleep [root@...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 -- Cheers, David / dhildenb
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