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* [PATCH] vhost: mask VIRTIO_F_RING_RESET for vhost and vhost-user devices
@ 2022-11-21 10:11 Stefano Garzarella
  2022-11-21 16:20 ` Stefan Hajnoczi
                   ` (2 more replies)
  0 siblings, 3 replies; 6+ messages in thread
From: Stefano Garzarella @ 2022-11-21 10:11 UTC (permalink / raw)
  To: qemu-devel
  Cc: qemu-block, virtio-fs, Alex Bennée, Viresh Kumar,
	Michael S. Tsirkin, Fam Zheng, Mathieu Poirier, Raphael Norwitz,
	Kevin Wolf, Dr. David Alan Gilbert, Stefan Hajnoczi,
	Paolo Bonzini, Hanna Reitz, kangjie.xu, Jason Wang,
	Stefano Garzarella

Commit 69e1c14aa2 ("virtio: core: vq reset feature negotation support")
enabled VIRTIO_F_RING_RESET by default for all virtio devices.

This feature is not currently emulated by QEMU, so for vhost and
vhost-user devices we need to make sure it is supported by the offloaded
device emulation (in-kernel or in another process).
To do this we need to add VIRTIO_F_RING_RESET to the features bitmap
passed to vhost_get_features(). This way it will be masked if the device
does not support it.

This issue was initially discovered with vhost-vsock and vhost-user-vsock,
and then also tested with vhost-user-rng which confirmed the same issue.
They fail when sending features through VHOST_SET_FEATURES ioctl or
VHOST_USER_SET_FEATURES message, since VIRTIO_F_RING_RESET is negotiated
by the guest (Linux >= v6.0), but not supported by the device.

Fixes: 69e1c14aa2 ("virtio: core: vq reset feature negotation support")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1318
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
---

To prevent this problem in the future, perhaps we should provide a function
(e.g. vhost_device_get_features) where we go to mask all non-device-specific
features (e.g VIRTIO_F_*, VIRTIO_RING_F_*) that are not emulated by QEMU but
we expect them to be emulated by the vhost or vhost-user devices.
Then we can call it in all .get_features callbacks just before return the
features.

What do you think?

But maybe better to do that for the next release, I will send an RFC.

Thanks,
Stefano
---
 hw/block/vhost-user-blk.c      |  1 +
 hw/net/vhost_net.c             |  1 +
 hw/scsi/vhost-scsi.c           |  1 +
 hw/scsi/vhost-user-scsi.c      |  1 +
 hw/virtio/vhost-user-fs.c      |  1 +
 hw/virtio/vhost-user-gpio.c    |  1 +
 hw/virtio/vhost-user-i2c.c     |  1 +
 hw/virtio/vhost-user-rng.c     | 11 +++++++++--
 hw/virtio/vhost-vsock-common.c |  1 +
 net/vhost-vdpa.c               |  1 +
 10 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c
index 16ad400889..0d5190accf 100644
--- a/hw/block/vhost-user-blk.c
+++ b/hw/block/vhost-user-blk.c
@@ -52,6 +52,7 @@ static const int user_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_F_RING_PACKED,
     VIRTIO_F_IOMMU_PLATFORM,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index feda448878..26e4930676 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -75,6 +75,7 @@ static const int user_feature_bits[] = {
     VIRTIO_NET_F_MTU,
     VIRTIO_F_IOMMU_PLATFORM,
     VIRTIO_F_RING_PACKED,
+    VIRTIO_F_RING_RESET,
     VIRTIO_NET_F_RSS,
     VIRTIO_NET_F_HASH_REPORT,
 
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index bdf337a7a2..6a0fd0dfb1 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -38,6 +38,7 @@ static const int kernel_feature_bits[] = {
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,
     VIRTIO_SCSI_F_HOTPLUG,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c
index bc37317d55..b7a71a802c 100644
--- a/hw/scsi/vhost-user-scsi.c
+++ b/hw/scsi/vhost-user-scsi.c
@@ -36,6 +36,7 @@ static const int user_feature_bits[] = {
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,
     VIRTIO_SCSI_F_HOTPLUG,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c
index 1c40f42045..dc4014cdef 100644
--- a/hw/virtio/vhost-user-fs.c
+++ b/hw/virtio/vhost-user-fs.c
@@ -32,6 +32,7 @@ static const int user_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_F_RING_PACKED,
     VIRTIO_F_IOMMU_PLATFORM,
+    VIRTIO_F_RING_RESET,
 
     VHOST_INVALID_FEATURE_BIT
 };
diff --git a/hw/virtio/vhost-user-gpio.c b/hw/virtio/vhost-user-gpio.c
index 677d1c7730..5851cb3bc9 100644
--- a/hw/virtio/vhost-user-gpio.c
+++ b/hw/virtio/vhost-user-gpio.c
@@ -24,6 +24,7 @@ static const int feature_bits[] = {
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,
     VIRTIO_GPIO_F_IRQ,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/hw/virtio/vhost-user-i2c.c b/hw/virtio/vhost-user-i2c.c
index 864eba695e..1c9f3d20dc 100644
--- a/hw/virtio/vhost-user-i2c.c
+++ b/hw/virtio/vhost-user-i2c.c
@@ -16,6 +16,7 @@
 
 static const int feature_bits[] = {
     VIRTIO_I2C_F_ZERO_LENGTH_REQUEST,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/hw/virtio/vhost-user-rng.c b/hw/virtio/vhost-user-rng.c
index 8b47287875..f9084cde58 100644
--- a/hw/virtio/vhost-user-rng.c
+++ b/hw/virtio/vhost-user-rng.c
@@ -16,6 +16,11 @@
 #include "qemu/error-report.h"
 #include "standard-headers/linux/virtio_ids.h"
 
+static const int feature_bits[] = {
+    VIRTIO_F_RING_RESET,
+    VHOST_INVALID_FEATURE_BIT
+};
+
 static void vu_rng_start(VirtIODevice *vdev)
 {
     VHostUserRNG *rng = VHOST_USER_RNG(vdev);
@@ -106,8 +111,10 @@ static void vu_rng_set_status(VirtIODevice *vdev, uint8_t status)
 static uint64_t vu_rng_get_features(VirtIODevice *vdev,
                                     uint64_t requested_features, Error **errp)
 {
-    /* No feature bits used yet */
-    return requested_features;
+    VHostUserRNG *rng = VHOST_USER_RNG(vdev);
+
+    return vhost_get_features(&rng->vhost_dev, feature_bits,
+                              requested_features);
 }
 
 static void vu_rng_handle_output(VirtIODevice *vdev, VirtQueue *vq)
diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
index 29b9ab4f72..a67a275de2 100644
--- a/hw/virtio/vhost-vsock-common.c
+++ b/hw/virtio/vhost-vsock-common.c
@@ -21,6 +21,7 @@
 
 const int feature_bits[] = {
     VIRTIO_VSOCK_F_SEQPACKET,
+    VIRTIO_F_RING_RESET,
     VHOST_INVALID_FEATURE_BIT
 };
 
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 6811089231..2b4b85d8f8 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -69,6 +69,7 @@ const int vdpa_feature_bits[] = {
     VIRTIO_NET_F_CTRL_VQ,
     VIRTIO_F_IOMMU_PLATFORM,
     VIRTIO_F_RING_PACKED,
+    VIRTIO_F_RING_RESET,
     VIRTIO_NET_F_RSS,
     VIRTIO_NET_F_HASH_REPORT,
     VIRTIO_NET_F_GUEST_ANNOUNCE,
-- 
2.38.1



^ permalink raw reply related	[flat|nested] 6+ messages in thread
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Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2022-11-21 10:11 [PATCH] vhost: mask VIRTIO_F_RING_RESET for vhost and vhost-user devices Stefano Garzarella
2022-11-21 16:20 ` Stefan Hajnoczi
2022-11-22  3:13 ` Jason Wang
2022-11-22 18:01   ` Eugenio Perez Martin
2022-11-23 14:24     ` Stefano Garzarella
2022-11-22  4:27 ` Raphael Norwitz

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