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Message-ID: <20240422070128.1980027-2-stevensd@chromium.org>
Date: Mon, 22 Apr 2024 16:01:28 +0900
From: David Stevens <stevensd@...omium.org>
To: "Michael S . Tsirkin" <mst@...hat.com>,
Jason Wang <jasowang@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Stefan Hajnoczi <stefanha@...hat.com>
Cc: Eugenio Perez <eperezma@...hat.com>,
Zhu Lingshan <lingshan.zhu@...el.com>,
virtio-dev@...ts.oasis-open.org,
linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org,
David Stevens <stevensd@...omium.org>
Subject: [PATCH v2 1/1] virtio: Add support for the virtio suspend feature
Add support for the VIRTIO_F_SUSPEND feature. When this feature is
negotiated, power management can use it to suspend virtio devices
instead of resorting to resetting the devices entirely.
Signed-off-by: David Stevens <stevensd@...omium.org>
---
drivers/virtio/virtio.c | 60 ++++++++++++++++++++++++++++++
drivers/virtio/virtio_pci_common.c | 34 ++++++++---------
drivers/virtio/virtio_pci_modern.c | 19 ++++++++++
include/linux/virtio.h | 8 ++++
include/uapi/linux/virtio_config.h | 10 ++++-
5 files changed, 112 insertions(+), 19 deletions(-)
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index f4080692b351..c7685a0dc995 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/virtio.h>
+#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <linux/virtio_anchor.h>
@@ -498,6 +499,13 @@ void unregister_virtio_device(struct virtio_device *dev)
}
EXPORT_SYMBOL_GPL(unregister_virtio_device);
+void virtio_device_mark_removed(struct virtio_device *dev)
+{
+ /* Pairs with READ_ONCE() in virtio_device_set_suspend_bit(). */
+ WRITE_ONCE(dev->removed, true);
+}
+EXPORT_SYMBOL_GPL(virtio_device_mark_removed);
+
#ifdef CONFIG_PM_SLEEP
int virtio_device_freeze(struct virtio_device *dev)
{
@@ -580,6 +588,58 @@ int virtio_device_restore(struct virtio_device *dev)
return ret;
}
EXPORT_SYMBOL_GPL(virtio_device_restore);
+
+static int virtio_device_set_suspend_bit(struct virtio_device *dev, bool enabled)
+{
+ u8 status, target;
+
+ status = dev->config->get_status(dev);
+ if (enabled)
+ target = status | VIRTIO_CONFIG_S_SUSPEND;
+ else
+ target = status & ~VIRTIO_CONFIG_S_SUSPEND;
+
+ if (target == status)
+ return 0;
+
+ dev->config->set_status(dev, target);
+
+ while ((status = dev->config->get_status(dev)) != target) {
+ if (status & VIRTIO_CONFIG_S_NEEDS_RESET)
+ return -EIO;
+ /* Pairs with WRITE_ONCE() in virtio_device_mark_removed(). */
+ if (READ_ONCE(dev->removed))
+ return -EIO;
+ msleep(10);
+ }
+ return 0;
+}
+
+bool virtio_device_can_suspend(struct virtio_device *dev)
+{
+ return virtio_has_feature(dev, VIRTIO_F_SUSPEND) &&
+ (dev->config->get_status(dev) & VIRTIO_CONFIG_S_FEATURES_OK);
+}
+EXPORT_SYMBOL_GPL(virtio_device_can_suspend);
+
+int virtio_device_suspend(struct virtio_device *dev)
+{
+ return virtio_device_set_suspend_bit(dev, true);
+}
+EXPORT_SYMBOL_GPL(virtio_device_suspend);
+
+bool virtio_device_can_resume(struct virtio_device *dev)
+{
+ return virtio_has_feature(dev, VIRTIO_F_SUSPEND) &&
+ (dev->config->get_status(dev) & VIRTIO_CONFIG_S_SUSPEND);
+}
+EXPORT_SYMBOL_GPL(virtio_device_can_resume);
+
+int virtio_device_resume(struct virtio_device *dev)
+{
+ return virtio_device_set_suspend_bit(dev, false);
+}
+EXPORT_SYMBOL_GPL(virtio_device_resume);
#endif
static int virtio_init(void)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index b655fccaf773..a6ca7718b5dc 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -495,31 +495,26 @@ 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)
+static int virtio_pci_suspend(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;
- }
+ struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
- return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
-}
+ if (virtio_device_can_suspend(&vp_dev->vdev))
+ return virtio_device_suspend(&vp_dev->vdev);
-static int virtio_pci_suspend(struct device *dev)
-{
- return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_freeze(dev);
+ return virtio_pci_freeze(dev);
}
static int virtio_pci_resume(struct device *dev)
{
- return vp_supports_pm_no_reset(dev) ? 0 : virtio_pci_restore(dev);
+ struct pci_dev *pci_dev = to_pci_dev(dev);
+ struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
+
+ if (virtio_device_can_resume(&vp_dev->vdev))
+ return virtio_device_resume(&vp_dev->vdev);
+
+ return virtio_pci_restore(dev);
}
static const struct dev_pm_ops virtio_pci_pm_ops = {
@@ -623,9 +618,12 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
* Device is marked broken on surprise removal so that virtio upper
* layers can abort any ongoing operation.
*/
- if (!pci_device_is_present(pci_dev))
+ if (!pci_device_is_present(pci_dev)) {
virtio_break_device(&vp_dev->vdev);
+ virtio_device_mark_removed(&vp_dev->vdev);
+ }
+
pci_disable_sriov(pci_dev);
unregister_virtio_device(&vp_dev->vdev);
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index f62b530aa3b5..ac8734526b8d 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -209,6 +209,22 @@ static void vp_modern_avq_deactivate(struct virtio_device *vdev)
__virtqueue_break(admin_vq->info.vq);
}
+static bool vp_supports_pm_no_reset(struct pci_dev *pci_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(&pci_dev->dev, "Unable to query pmcsr");
+ return false;
+ }
+
+ return pmcsr & PCI_PM_CTRL_NO_SOFT_RESET;
+}
+
static void vp_transport_features(struct virtio_device *vdev, u64 features)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -223,6 +239,9 @@ static void vp_transport_features(struct virtio_device *vdev, u64 features)
if (features & BIT_ULL(VIRTIO_F_ADMIN_VQ))
__virtio_set_bit(vdev, VIRTIO_F_ADMIN_VQ);
+
+ if (features & BIT_ULL(VIRTIO_F_SUSPEND) && vp_supports_pm_no_reset(pci_dev))
+ __virtio_set_bit(vdev, VIRTIO_F_SUSPEND);
}
static int __vp_check_common_size_one_feature(struct virtio_device *vdev, u32 fbit,
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b0201747a263..2ca2ae290d4f 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -115,6 +115,7 @@ struct virtio_admin_cmd {
* struct virtio_device - representation of a device using virtio
* @index: unique position on the virtio bus
* @failed: saved value for VIRTIO_CONFIG_S_FAILED bit (for restore)
+ * @removed: whether or not the device was removed from under us
* @config_enabled: configuration change reporting enabled
* @config_change_pending: configuration change reported while disabled
* @config_lock: protects configuration change reporting
@@ -130,6 +131,7 @@ struct virtio_admin_cmd {
struct virtio_device {
int index;
bool failed;
+ bool removed;
bool config_enabled;
bool config_change_pending;
spinlock_t config_lock;
@@ -156,10 +158,16 @@ void __virtio_unbreak_device(struct virtio_device *dev);
void __virtqueue_break(struct virtqueue *_vq);
void __virtqueue_unbreak(struct virtqueue *_vq);
+void virtio_device_mark_removed(struct virtio_device *dev);
+
void virtio_config_changed(struct virtio_device *dev);
#ifdef CONFIG_PM_SLEEP
int virtio_device_freeze(struct virtio_device *dev);
int virtio_device_restore(struct virtio_device *dev);
+bool virtio_device_can_suspend(struct virtio_device *dev);
+bool virtio_device_can_resume(struct virtio_device *dev);
+int virtio_device_suspend(struct virtio_device *dev);
+int virtio_device_resume(struct virtio_device *dev);
#endif
void virtio_reset_device(struct virtio_device *dev);
diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
index 2445f365bce7..4a6e2c28ea76 100644
--- a/include/uapi/linux/virtio_config.h
+++ b/include/uapi/linux/virtio_config.h
@@ -40,6 +40,8 @@
#define VIRTIO_CONFIG_S_DRIVER_OK 4
/* Driver has finished configuring features */
#define VIRTIO_CONFIG_S_FEATURES_OK 8
+/* Driver has suspended the device */
+#define VIRTIO_CONFIG_S_SUSPEND 0x10
/* Device entered invalid state, driver must reset it */
#define VIRTIO_CONFIG_S_NEEDS_RESET 0x40
/* We've given up on this device. */
@@ -52,7 +54,7 @@
* rest are per-device feature bits.
*/
#define VIRTIO_TRANSPORT_F_START 28
-#define VIRTIO_TRANSPORT_F_END 42
+#define VIRTIO_TRANSPORT_F_END 43
#ifndef VIRTIO_CONFIG_NO_LEGACY
/* Do we get callbacks when the ring is completely used, even if we've
@@ -120,4 +122,10 @@
*/
#define VIRTIO_F_ADMIN_VQ 41
+/*
+ * This feature indicates that the driver can suspend the device via the
+ * suspend bit in the device status byte.
+ */
+#define VIRTIO_F_SUSPEND 42
+
#endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
--
2.44.0.769.g3c40516874-goog
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