From dff4fa0e57856045359440d05af9e9b7f7048f52 Mon Sep 17 00:00:00 2001 From: David Stevens Date: Fri, 8 Dec 2023 16:07:54 +0900 Subject: virtio: Add support for no-reset virtio PCI PM 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 Message-Id: <20231208070754.3132339-1-stevensd@chromium.org> Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang --- drivers/virtio/virtio_pci_common.c | 34 +++++++++++++++++++++++++++++++++- 1 file changed, 33 insertions(+), 1 deletion(-) (limited to 'drivers/virtio') diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c index 7a5593997e0e..1d21d1a1b3f5 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 -- cgit v1.2.3