From: Alex Williamson Date: Sat, 9 Feb 2019 20:43:30 +0000 (-0700) Subject: vfio/pci: Restore device state on PM transition X-Git-Tag: v5.4-rc1~1552^2~1 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=51ef3a004b1eb6241e56b3aa8495769a092a4dc2;p=platform%2Fkernel%2Flinux-rpi.git vfio/pci: Restore device state on PM transition PCI core handles save and restore of device state around reset, but when using pci_set_power_state() we can unintentionally trigger a soft reset of the device, where PCI core only restores the BAR state. If we're using vfio-pci's idle D3 support to try to put devices into low power when unused, this might trigger a reset when the device is woken for use. Also power state management by the user, or within a guest, can put the device into D3 power state with potentially limited ability to restore the device if it should undergo a reset. The PCI spec does not define the extent of a soft reset and many devices reporting soft reset on D3->D0 transition do not undergo a PCI config space reset. It's therefore assumed safe to unconditionally restore the remainder of the state if the device indicates soft reset support, even on a user initiated wakeup. Implement a wrapper in vfio-pci to tag devices reporting PM reset support, save their state on transitions into D3 and restore on transitions back to D0. Reported-by: Alexander Duyck Signed-off-by: Alex Williamson --- diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index ff60bd1..84b593b 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -209,6 +209,57 @@ static bool vfio_pci_nointx(struct pci_dev *pdev) return false; } +static void vfio_pci_probe_power_state(struct vfio_pci_device *vdev) +{ + struct pci_dev *pdev = vdev->pdev; + u16 pmcsr; + + if (!pdev->pm_cap) + return; + + pci_read_config_word(pdev, pdev->pm_cap + PCI_PM_CTRL, &pmcsr); + + vdev->needs_pm_restore = !(pmcsr & PCI_PM_CTRL_NO_SOFT_RESET); +} + +/* + * pci_set_power_state() wrapper handling devices which perform a soft reset on + * D3->D0 transition. Save state prior to D0/1/2->D3, stash it on the vdev, + * restore when returned to D0. Saved separately from pci_saved_state for use + * by PM capability emulation and separately from pci_dev internal saved state + * to avoid it being overwritten and consumed around other resets. + */ +int vfio_pci_set_power_state(struct vfio_pci_device *vdev, pci_power_t state) +{ + struct pci_dev *pdev = vdev->pdev; + bool needs_restore = false, needs_save = false; + int ret; + + if (vdev->needs_pm_restore) { + if (pdev->current_state < PCI_D3hot && state >= PCI_D3hot) { + pci_save_state(pdev); + needs_save = true; + } + + if (pdev->current_state >= PCI_D3hot && state <= PCI_D0) + needs_restore = true; + } + + ret = pci_set_power_state(pdev, state); + + if (!ret) { + /* D3 might be unsupported via quirk, skip unless in D3 */ + if (needs_save && pdev->current_state >= PCI_D3hot) { + vdev->pm_save = pci_store_saved_state(pdev); + } else if (needs_restore) { + pci_load_and_free_saved_state(pdev, &vdev->pm_save); + pci_restore_state(pdev); + } + } + + return ret; +} + static int vfio_pci_enable(struct vfio_pci_device *vdev) { struct pci_dev *pdev = vdev->pdev; @@ -216,7 +267,7 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev) u16 cmd; u8 msix_pos; - pci_set_power_state(pdev, PCI_D0); + vfio_pci_set_power_state(vdev, PCI_D0); /* Don't allow our initial saved state to include busmaster */ pci_clear_master(pdev); @@ -407,7 +458,7 @@ out: vfio_pci_try_bus_reset(vdev); if (!disable_idle_d3) - pci_set_power_state(pdev, PCI_D3hot); + vfio_pci_set_power_state(vdev, PCI_D3hot); } static void vfio_pci_release(void *device_data) @@ -1286,6 +1337,8 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) vfio_pci_set_vga_decode(vdev, false)); } + vfio_pci_probe_power_state(vdev); + if (!disable_idle_d3) { /* * pci-core sets the device power state to an unknown value at @@ -1296,8 +1349,8 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) * be able to get to D3. Therefore first do a D0 transition * before going to D3. */ - pci_set_power_state(pdev, PCI_D0); - pci_set_power_state(pdev, PCI_D3hot); + vfio_pci_set_power_state(vdev, PCI_D0); + vfio_pci_set_power_state(vdev, PCI_D3hot); } return ret; @@ -1316,6 +1369,11 @@ static void vfio_pci_remove(struct pci_dev *pdev) vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev); kfree(vdev->region); mutex_destroy(&vdev->ioeventfds_lock); + + if (!disable_idle_d3) + vfio_pci_set_power_state(vdev, PCI_D0); + + kfree(vdev->pm_save); kfree(vdev); if (vfio_pci_is_vga(pdev)) { @@ -1324,9 +1382,6 @@ static void vfio_pci_remove(struct pci_dev *pdev) VGA_RSRC_NORMAL_IO | VGA_RSRC_NORMAL_MEM | VGA_RSRC_LEGACY_IO | VGA_RSRC_LEGACY_MEM); } - - if (!disable_idle_d3) - pci_set_power_state(pdev, PCI_D0); } static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev, @@ -1551,7 +1606,7 @@ put_devs: tmp->needs_reset = false; if (tmp != vdev && !disable_idle_d3) - pci_set_power_state(tmp->pdev, PCI_D3hot); + vfio_pci_set_power_state(tmp, PCI_D3hot); } vfio_device_put(devs.devices[i]); diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c index 423ea1f..e82b511 100644 --- a/drivers/vfio/pci/vfio_pci_config.c +++ b/drivers/vfio/pci/vfio_pci_config.c @@ -691,7 +691,7 @@ static int vfio_pm_config_write(struct vfio_pci_device *vdev, int pos, break; } - pci_set_power_state(vdev->pdev, state); + vfio_pci_set_power_state(vdev, state); } return count; diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h index 8c0009f..1812cf2 100644 --- a/drivers/vfio/pci/vfio_pci_private.h +++ b/drivers/vfio/pci/vfio_pci_private.h @@ -114,7 +114,9 @@ struct vfio_pci_device { bool has_vga; bool needs_reset; bool nointx; + bool needs_pm_restore; struct pci_saved_state *pci_saved_state; + struct pci_saved_state *pm_save; struct vfio_pci_reflck *reflck; int refcnt; int ioeventfds_nr; @@ -161,6 +163,10 @@ extern int vfio_pci_register_dev_region(struct vfio_pci_device *vdev, unsigned int type, unsigned int subtype, const struct vfio_pci_regops *ops, size_t size, u32 flags, void *data); + +extern int vfio_pci_set_power_state(struct vfio_pci_device *vdev, + pci_power_t state); + #ifdef CONFIG_VFIO_PCI_IGD extern int vfio_pci_igd_init(struct vfio_pci_device *vdev); #else