From 838d6d3461db0fdbf33fc5f8a69c27b50b4a46da Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Fri, 14 Jan 2022 14:56:15 -0500 Subject: virtio: unexport virtio_finalize_features virtio_finalize_features is only used internally within virtio. No reason to export it. Signed-off-by: Michael S. Tsirkin Reviewed-by: Cornelia Huck Acked-by: Jason Wang --- include/linux/virtio.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/virtio.h b/include/linux/virtio.h index 72292a62cd90..5464f398912a 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -133,7 +133,6 @@ bool is_virtio_device(struct device *dev); void virtio_break_device(struct virtio_device *dev); void virtio_config_changed(struct virtio_device *dev); -int virtio_finalize_features(struct virtio_device *dev); #ifdef CONFIG_PM_SLEEP int virtio_device_freeze(struct virtio_device *dev); int virtio_device_restore(struct virtio_device *dev); -- cgit v1.2.3-70-g09d2 From 4fa59ede95195f267101a1b8916992cf3f245cdb Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Fri, 14 Jan 2022 14:58:41 -0500 Subject: virtio: acknowledge all features before access The feature negotiation was designed in a way that makes it possible for devices to know which config fields will be accessed by drivers. This is broken since commit 404123c2db79 ("virtio: allow drivers to validate features") with fallout in at least block and net. We have a partial work-around in commit 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") which at least lets devices find out which format should config space have, but this is a partial fix: guests should not access config space without acknowledging features since otherwise we'll never be able to change the config space format. To fix, split finalize_features from virtio_finalize_features and call finalize_features with all feature bits before validation, and then - if validation changed any bits - once again after. Since virtio_finalize_features no longer writes out features rename it to virtio_features_ok - since that is what it does: checks that features are ok with the device. As a side effect, this also reduces the amount of hypervisor accesses - we now only acknowledge features once unless we are clearing any features when validating (which is uncommon). IRC I think that this was more or less always the intent in the spec but unfortunately the way the spec is worded does not say this explicitly, I plan to address this at the spec level, too. Acked-by: Jason Wang Cc: stable@vger.kernel.org Fixes: 404123c2db79 ("virtio: allow drivers to validate features") Fixes: 2f9a174f918e ("virtio: write back F_VERSION_1 before validate") Cc: "Halil Pasic" Signed-off-by: Michael S. Tsirkin --- drivers/virtio/virtio.c | 39 ++++++++++++++++++++++----------------- include/linux/virtio_config.h | 3 ++- 2 files changed, 24 insertions(+), 18 deletions(-) (limited to 'include/linux') diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index d891b0a354b0..d6396be0ea83 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -166,14 +166,13 @@ void virtio_add_status(struct virtio_device *dev, unsigned int status) } EXPORT_SYMBOL_GPL(virtio_add_status); -static int virtio_finalize_features(struct virtio_device *dev) +/* Do some validation, then set FEATURES_OK */ +static int virtio_features_ok(struct virtio_device *dev) { - int ret = dev->config->finalize_features(dev); unsigned status; + int ret; might_sleep(); - if (ret) - return ret; ret = arch_has_restricted_virtio_memory_access(); if (ret) { @@ -244,17 +243,6 @@ static int virtio_dev_probe(struct device *_d) driver_features_legacy = driver_features; } - /* - * Some devices detect legacy solely via F_VERSION_1. Write - * F_VERSION_1 to force LE config space accesses before FEATURES_OK for - * these when needed. - */ - if (drv->validate && !virtio_legacy_is_little_endian() - && device_features & BIT_ULL(VIRTIO_F_VERSION_1)) { - dev->features = BIT_ULL(VIRTIO_F_VERSION_1); - dev->config->finalize_features(dev); - } - if (device_features & (1ULL << VIRTIO_F_VERSION_1)) dev->features = driver_features & device_features; else @@ -265,13 +253,26 @@ static int virtio_dev_probe(struct device *_d) if (device_features & (1ULL << i)) __virtio_set_bit(dev, i); + err = dev->config->finalize_features(dev); + if (err) + goto err; + if (drv->validate) { + u64 features = dev->features; + err = drv->validate(dev); if (err) goto err; + + /* Did validation change any features? Then write them again. */ + if (features != dev->features) { + err = dev->config->finalize_features(dev); + if (err) + goto err; + } } - err = virtio_finalize_features(dev); + err = virtio_features_ok(dev); if (err) goto err; @@ -495,7 +496,11 @@ int virtio_device_restore(struct virtio_device *dev) /* We have a driver! */ virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER); - ret = virtio_finalize_features(dev); + ret = dev->config->finalize_features(dev); + if (ret) + goto err; + + ret = virtio_features_ok(dev); if (ret) goto err; diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h index 4d107ad31149..dafdc7f48c01 100644 --- a/include/linux/virtio_config.h +++ b/include/linux/virtio_config.h @@ -64,8 +64,9 @@ struct virtio_shm_region { * Returns the first 64 feature bits (all we currently need). * @finalize_features: confirm what device features we'll be using. * vdev: the virtio_device - * This gives the final feature bits for the device: it can change + * This sends the driver feature bits to the device: it can change * the dev->feature bits if it wants. + * Note: despite the name this can be called any number of times. * Returns 0 on success or error status * @bus_name: return the bus name associated with the device (optional) * vdev: the virtio_device -- cgit v1.2.3-70-g09d2 From e0077cc13b831f8fad5557442f73bf7728683713 Mon Sep 17 00:00:00 2001 From: Si-Wei Liu Date: Fri, 14 Jan 2022 19:27:59 -0500 Subject: vdpa: factor out vdpa_set_features_unlocked for vdpa internal use No functional change introduced. vdpa bus driver such as virtio_vdpa or vhost_vdpa is not supposed to take care of the locking for core by its own. The locked API vdpa_set_features should suffice the bus driver's need. Signed-off-by: Si-Wei Liu Reviewed-by: Eli Cohen Link: https://lore.kernel.org/r/1642206481-30721-2-git-send-email-si-wei.liu@oracle.com Signed-off-by: Michael S. Tsirkin Acked-by: Jason Wang --- drivers/vdpa/vdpa.c | 2 +- drivers/vhost/vdpa.c | 2 +- drivers/virtio/virtio_vdpa.c | 2 +- include/linux/vdpa.h | 18 ++++++++++++------ 4 files changed, 15 insertions(+), 9 deletions(-) (limited to 'include/linux') diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c index 9846c9de4bfa..1ea525433a5c 100644 --- a/drivers/vdpa/vdpa.c +++ b/drivers/vdpa/vdpa.c @@ -393,7 +393,7 @@ static void vdpa_get_config_unlocked(struct vdpa_device *vdev, * If it does happen we assume a legacy guest. */ if (!vdev->features_valid) - vdpa_set_features(vdev, 0, true); + vdpa_set_features_unlocked(vdev, 0); ops->get_config(vdev, offset, buf, len); } diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index 851539807bc9..ec5249e8c32d 100644 --- a/drivers/vhost/vdpa.c +++ b/drivers/vhost/vdpa.c @@ -286,7 +286,7 @@ static long vhost_vdpa_set_features(struct vhost_vdpa *v, u64 __user *featurep) if (copy_from_user(&features, featurep, sizeof(features))) return -EFAULT; - if (vdpa_set_features(vdpa, features, false)) + if (vdpa_set_features(vdpa, features)) return -EINVAL; return 0; diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c index 7767a7f0119b..76504559bc25 100644 --- a/drivers/virtio/virtio_vdpa.c +++ b/drivers/virtio/virtio_vdpa.c @@ -317,7 +317,7 @@ static int virtio_vdpa_finalize_features(struct virtio_device *vdev) /* Give virtio_ring a chance to accept features. */ vring_transport_features(vdev); - return vdpa_set_features(vdpa, vdev->features, false); + return vdpa_set_features(vdpa, vdev->features); } static const char *virtio_vdpa_bus_name(struct virtio_device *vdev) diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h index 2de442ececae..721089bb4c84 100644 --- a/include/linux/vdpa.h +++ b/include/linux/vdpa.h @@ -401,18 +401,24 @@ static inline int vdpa_reset(struct vdpa_device *vdev) return ret; } -static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features, bool locked) +static inline int vdpa_set_features_unlocked(struct vdpa_device *vdev, u64 features) { const struct vdpa_config_ops *ops = vdev->config; int ret; - if (!locked) - mutex_lock(&vdev->cf_mutex); - vdev->features_valid = true; ret = ops->set_driver_features(vdev, features); - if (!locked) - mutex_unlock(&vdev->cf_mutex); + + return ret; +} + +static inline int vdpa_set_features(struct vdpa_device *vdev, u64 features) +{ + int ret; + + mutex_lock(&vdev->cf_mutex); + ret = vdpa_set_features_unlocked(vdev, features); + mutex_unlock(&vdev->cf_mutex); return ret; } -- cgit v1.2.3-70-g09d2