On Wed, 16 Sept 2026 at 09:51, Mathieu Poirier <[email protected]> wrote: > > On Tue, Sep 15, 2026 at 12:20:34PM -0500, Shah, Tanmay wrote: > > > > > > On 9/14/2026 11:47 AM, Mathieu Poirier wrote: > > > On Fri, 11 Sept 2026 at 12:03, Shah, Tanmay <[email protected]> wrote: > > >> > > >> > > >> > > >> On 9/11/2026 9:57 AM, Mathieu Poirier wrote: > > >>> On Tue, Sep 08, 2026 at 02:21:53PM -0500, Shah, Tanmay wrote: > > >>>> Hello, > > >>>> > > >>>> Thank you for the reviews. > > >>>> > > >>>> On 9/8/2026 1:02 PM, Mathieu Poirier wrote: > > >>>>> Good day, > > >>>>> > > >>>>> On Wed, Sep 02, 2026 at 02:44:54PM -0700, Tanmay Shah wrote: > > >>>>>> The existing remoteproc virtio reset path clears the vdev status > > >>>>>> locally > > >>>>>> without notifying the remote processor. As a result, the host cannot > > >>>>>> tell > > >>>>>> whether the remote side has observed the reset request or completed > > >>>>>> its > > >>>>>> cleanup. > > >>>>>> > > >>>>>> Add a new resource type, RSC_VDEV_V2, for virtio vdevs that support > > >>>>>> an > > >>>>>> acknowledged reset protocol. For these resources, encode a reset > > >>>>>> request > > >>>>>> in the virtio status byte, kick the remote processor using the vdev > > >>>>>> notify > > >>>>>> ID, and wait for the remote side to clear the status back to 0. > > >>>>>> > > >>>>>> Keep the existing RSC_VDEV behavior for backwards compatibility by > > >>>>>> clearing the status locally. Also reset remoteproc-created virtio > > >>>>>> devices before unregistering them, and expose RSC_VDEV_V2 reset state > > >>>>>> in debugfs. > > >>>>>> > > >>>>>> Assisted-by: Codex:GPT-5 > > >>>>>> Signed-off-by: Tanmay Shah <[email protected]> > > >>>>>> --- > > >>>>>> drivers/remoteproc/remoteproc_core.c | 3 +- > > >>>>>> drivers/remoteproc/remoteproc_debugfs.c | 29 +++++++++++++++- > > >>>>>> drivers/remoteproc/remoteproc_internal.h | 21 +++++++++++ > > >>>>>> drivers/remoteproc/remoteproc_virtio.c | 44 > > >>>>>> ++++++++++++++++++++++-- > > >>>>>> include/linux/rsc_table.h | 5 ++- > > >>>>>> 5 files changed, 97 insertions(+), 5 deletions(-) > > >>>>>> > > >>>>>> diff --git a/drivers/remoteproc/remoteproc_core.c > > >>>>>> b/drivers/remoteproc/remoteproc_core.c > > >>>>>> index 1ed406714849..31d79684977c 100644 > > >>>>>> --- a/drivers/remoteproc/remoteproc_core.c > > >>>>>> +++ b/drivers/remoteproc/remoteproc_core.c > > >>>>>> @@ -471,6 +471,7 @@ void rproc_remove_rvdev(struct rproc_vdev *rvdev) > > >>>>>> static int rproc_handle_vdev(struct rproc *rproc, void *ptr, > > >>>>>> int offset, int avail) > > >>>>>> { > > >>>>>> + struct fw_rsc_hdr *hdr = ptr - sizeof(*hdr); > > >>>>> > > >>>>> Spurious change. > > >>>>> > > >>>> > > >>>> Ack will remove it. > > >>>> > > >>>>>> struct fw_rsc_vdev *rsc = ptr; > > >>>>>> struct device *dev = &rproc->dev; > > >>>>>> struct rproc_vdev *rvdev; > > >>>>>> @@ -485,7 +486,6 @@ static int rproc_handle_vdev(struct rproc > > >>>>>> *rproc, void *ptr, > > >>>>>> return -EINVAL; > > >>>>>> } > > >>>>>> > > >>>>>> - /* make sure reserved bytes are zeroes */ > > >>>>> > > >>>>> Same > > >>>> > > >>>> Ack, will be removed. > > >>>> > > >>>>> > > >>>>>> if (rsc->reserved[0] || rsc->reserved[1]) { > > >>>>>> dev_err(dev, "vdev rsc has non zero reserved bytes\n"); > > >>>>>> return -EINVAL; > > >>>>>> @@ -1009,6 +1009,7 @@ static rproc_handle_resource_t > > >>>>>> rproc_loading_handlers[RSC_LAST] = { > > >>>>>> [RSC_DEVMEM] = rproc_handle_devmem, > > >>>>>> [RSC_TRACE] = rproc_handle_trace, > > >>>>>> [RSC_VDEV] = rproc_handle_vdev, > > >>>>>> + [RSC_VDEV_V2] = rproc_handle_vdev, > > >>>>>> }; > > >>>>>> > > >>>>>> struct rproc_rsc_cb_data { > > >>>>>> diff --git a/drivers/remoteproc/remoteproc_debugfs.c > > >>>>>> b/drivers/remoteproc/remoteproc_debugfs.c > > >>>>>> index b86c1d09c70c..1fe99749f5b4 100644 > > >>>>>> --- a/drivers/remoteproc/remoteproc_debugfs.c > > >>>>>> +++ b/drivers/remoteproc/remoteproc_debugfs.c > > >>>>>> @@ -274,7 +274,7 @@ static const struct file_operations > > >>>>>> rproc_crash_ops = { > > >>>>>> /* Expose resource table content via debugfs */ > > >>>>>> static int rproc_rsc_table_show(struct seq_file *seq, void *p) > > >>>>>> { > > >>>>>> - static const char * const types[] = {"carveout", "devmem", > > >>>>>> "trace", "vdev"}; > > >>>>>> + static const char * const types[] = {"carveout", "devmem", > > >>>>>> "trace", "vdev", "vdev_v2"}; > > >>>>>> struct rproc *rproc = seq->private; > > >>>>>> struct resource_table *table = rproc->table_ptr; > > >>>>>> struct fw_rsc_carveout *c; > > >>>>>> @@ -336,6 +336,33 @@ static int rproc_rsc_table_show(struct seq_file > > >>>>>> *seq, void *p) > > >>>>>> seq_printf(seq, " Reserved (should be zero) > > >>>>>> [%d][%d]\n\n", > > >>>>>> v->reserved[0], v->reserved[1]); > > >>>>>> > > >>>>>> + for (j = 0; j < v->num_of_vrings; j++) { > > >>>>>> + seq_printf(seq, " Vring %d\n", j); > > >>>>>> + seq_printf(seq, " Device Address > > >>>>>> 0x%x\n", v->vring[j].da); > > >>>>>> + seq_printf(seq, " Alignment %d\n", > > >>>>>> v->vring[j].align); > > >>>>>> + seq_printf(seq, " Number of buffers > > >>>>>> %d\n", v->vring[j].num); > > >>>>>> + seq_printf(seq, " Notify ID %d\n", > > >>>>>> v->vring[j].notifyid); > > >>>>>> + seq_printf(seq, " Physical Address > > >>>>>> 0x%x\n\n", > > >>>>>> + v->vring[j].pa); > > >>>>>> + } > > >>>>>> + break; > > >>>>>> + case RSC_VDEV_V2: > > >>>>>> + v = rsc; > > >>>>>> + seq_printf(seq, "Entry %d is of type %s\n", i, > > >>>>>> types[hdr->type]); > > >>>>>> + > > >>>>>> + seq_printf(seq, " ID %d\n", v->id); > > >>>>>> + seq_printf(seq, " Notify ID %d\n", v->notifyid); > > >>>>>> + seq_printf(seq, " Device features 0x%x\n", > > >>>>>> v->dfeatures); > > >>>>>> + seq_printf(seq, " Guest features 0x%x\n", > > >>>>>> v->gfeatures); > > >>>>>> + seq_printf(seq, " Config length 0x%x\n", > > >>>>>> v->config_len); > > >>>>>> + seq_printf(seq, " Status 0x%x\n", v->status); > > >>>>>> + seq_printf(seq, " Number of vrings %d\n", > > >>>>>> v->num_of_vrings); > > >>>>>> + seq_printf(seq, " Reset request pending %s\n", > > >>>>>> + > > >>>>>> rproc_rsc_vdev_reset_requested(v->status) ? > > >>>>>> + "yes" : "no"); > > >>>>>> + seq_printf(seq, " Reserved (should be zero) > > >>>>>> [%d][%d]\n\n", > > >>>>>> + v->reserved[0], v->reserved[1]); > > >>>>>> + > > >>>>>> for (j = 0; j < v->num_of_vrings; j++) { > > >>>>>> seq_printf(seq, " Vring %d\n", j); > > >>>>>> seq_printf(seq, " Device Address > > >>>>>> 0x%x\n", v->vring[j].da); > > >>>>>> diff --git a/drivers/remoteproc/remoteproc_internal.h > > >>>>>> b/drivers/remoteproc/remoteproc_internal.h > > >>>>>> index 3a742ef6ef60..f07a96ff82a4 100644 > > >>>>>> --- a/drivers/remoteproc/remoteproc_internal.h > > >>>>>> +++ b/drivers/remoteproc/remoteproc_internal.h > > >>>>>> @@ -14,6 +14,7 @@ > > >>>>>> > > >>>>>> #include <linux/irqreturn.h> > > >>>>>> #include <linux/firmware.h> > > >>>>>> +#include <linux/virtio_config.h> > > >>>>>> #ifdef CONFIG_HAS_IOMEM > > >>>>>> #include <linux/io.h> > > >>>>>> #endif > > >>>>>> @@ -42,6 +43,26 @@ struct rproc_vdev_data { > > >>>>>> struct fw_rsc_vdev *rsc; > > >>>>>> }; > > >>>>>> > > >>>>>> +/* > > >>>>>> + * RSC_VDEV_V2 requests an acknowledged reset by writing an > > >>>>>> otherwise > > >>>>>> + * impossible virtio status pattern: DRIVER and FAILED set while > > >>>>>> + * ACKNOWLEDGE is clear. Other status bits are left unchanged. > > >>>>>> + */ > > >>>>>> +static inline u8 rproc_rsc_vdev_reset_status(u8 status) > > >>>>>> +{ > > >>>>>> + status |= VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_FAILED; > > >>>>>> + status &= ~VIRTIO_CONFIG_S_ACKNOWLEDGE; > > >>>>>> + > > >>>>>> + return status; > > >>>>>> +} > > >>>>>> + > > >>>>>> +static inline bool rproc_rsc_vdev_reset_requested(u8 status) > > >>>>>> +{ > > >>>>>> + return !(status & VIRTIO_CONFIG_S_ACKNOWLEDGE) && > > >>>>>> + (status & VIRTIO_CONFIG_S_DRIVER) && > > >>>>>> + (status & VIRTIO_CONFIG_S_FAILED); > > >>>>>> +} > > >>>>>> + > > >>>>>> static inline bool rproc_has_feature(struct rproc *rproc, unsigned > > >>>>>> int feature) > > >>>>>> { > > >>>>>> return test_bit(feature, rproc->features); > > >>>>>> diff --git a/drivers/remoteproc/remoteproc_virtio.c > > >>>>>> b/drivers/remoteproc/remoteproc_virtio.c > > >>>>>> index d5e9ff045a28..e682caa546b2 100644 > > >>>>>> --- a/drivers/remoteproc/remoteproc_virtio.c > > >>>>>> +++ b/drivers/remoteproc/remoteproc_virtio.c > > >>>>>> @@ -13,6 +13,7 @@ > > >>>>>> #include <linux/dma-map-ops.h> > > >>>>>> #include <linux/dma-mapping.h> > > >>>>>> #include <linux/export.h> > > >>>>>> +#include <linux/iopoll.h> > > >>>>>> #include <linux/of_reserved_mem.h> > > >>>>>> #include <linux/platform_device.h> > > >>>>>> #include <linux/remoteproc.h> > > >>>>>> @@ -234,12 +235,48 @@ static void rproc_virtio_set_status(struct > > >>>>>> virtio_device *vdev, u8 status) > > >>>>>> static void rproc_virtio_reset(struct virtio_device *vdev) > > >>>>>> { > > >>>>>> struct rproc_vdev *rvdev = vdev_to_rvdev(vdev); > > >>>>>> + struct rproc *rproc = rvdev->rproc; > > >>>>>> struct fw_rsc_vdev *rsc; > > >>>>>> + struct fw_rsc_hdr *hdr; > > >>>>>> + int ret; > > >>>>>> + u8 val; > > >>>>>> + > > >>>>>> + /* > > >>>>>> + * During crash recovery, vdev can be stopped. But the driver > > >>>>>> can't reset > > >>>>>> + * the device, as device is already crashed. In this case, reset > > >>>>>> becomes > > >>>>>> + * no op. > > >>>>>> + */ > > >>>>>> + if (rproc->state == RPROC_CRASHED) > > >>>>>> + return; > > >>>>>> > > >>>>>> rsc = (void *)rvdev->rproc->table_ptr + rvdev->rsc_offset; > > >>>>>> + hdr = (void *)rsc - sizeof(*hdr); > > >>>>>> + > > >>>>>> + if (hdr->type == RSC_VDEV_V2) { > > >>>>>> + /* > > >>>>>> + * RSC_VDEV_V2 encodes an acknowledged reset request in > > >>>>>> the > > >>>>>> + * status byte. The remote is expected to complete the > > >>>>>> reset > > >>>>>> + * and then clear status back to 0. > > >>>>>> + */ > > >>>>>> + rsc->status = rproc_rsc_vdev_reset_status(rsc->status); > > >>>>>> + > > >>>>>> + /* after setting reset request, kick the device */ > > >>>>>> + rproc->ops->kick(rproc, rsc->notifyid); > > >>>>>> > > >>>>>> - rsc->status = 0; > > >>>>>> - dev_dbg(&vdev->dev, "reset !\n"); > > >>>>>> + /* > > >>>>>> + * When device completes reset, it is expected to set > > >>>>>> status > > >>>>>> + * to 0. > > >>>>>> + */ > > >>>>>> + ret = readb_poll_timeout(&rsc->status, val, val == 0, > > >>>>>> + 1000, /* 1ms between reads > > >>>>>> */ > > >>>>>> + 3000000); /* 3s total timeout */ > > >>>>>> + if (ret) > > >>>>>> + dev_warn(&vdev->dev, "vdev reset timed out\n"); > > >>>>> > > >>>>> The problem here is that we are introducing behavior that is not > > >>>>> compliant with > > >>>>> the virtio specifications. One way to acheive the same behavior > > >>>>> could be for > > >>>>> the remote processor to check rsc->status before sending a interrupt > > >>>>> of using > > >>>>> the virtqueues. > > >>>>> > > >>>> > > >>>> That is what remote is supposed to do. But what if remote do not > > >>>> respond? If remote is deadlocked for some reason, then the Linux will > > >>>> hang at this point too. That is why we need some kind of timeout. > > >>> > > >>> If the remote is dead then a watchdog timer should fire at some point. > > >>> Moreover, that situation won't be different from other circumstances > > >>> where a > > >>> remote processor locks up. > > >>> > > >> > > >> There are few concerns: > > >> > > >> 1) Heterogeneous system where Linux is handling many remotes, the > > >> watchdog might not be available to all the remotes or watchdog mechanism > > >> is not implemented at all on the remote side. > > > > > > If a watchdog is not available adding a timeout upon resetting > > > rsc-status won't help. > > > > > >> > > >> 2) Let's say watchdog is configured for 10s, or so then for that long > > >> Linux will be stuck too. I am trying to avoid this case where Linux gets > > >> stuck for long time. > > > > > > Same resoning as above - if the remote processor dies and a watchdog > > > timeout is set for 10 seconds, adding a shorter timeout when > > > rsc->status is modified will do very little. > > > > > >>> Looking at your patch, sending a kick() won't do anything for a dead > > >>> remote > > >>> processor. If the remote processor is alive, it should monitor > > >>> rsc->status and > > >>> take action when it is set to '0' by the host. If it is locked-up, the > > >>> normal > > >>> lockup procedure should apply. > > >>> > > >> > > >> Notifying virtio device on the status change is standard virtio > > >> mechanism. In the virtio statck it's done via virtqueue_notify so I am > > >> trying to do the same. It also helps remote to avoid polling on status. > > >> > > > > > > Can you point me to that code? Having the same mental picture will help. > > > > > >>> I'm not sure what problem this patch is trying to address. > > >>> > > >> > > >> Some platforms allow Linux and Remote boot independently. > > >> > > >> Let's say Linux reboots without reseting the remote then during next > > >> boot Linux will find virtio status is not in the reset state. > > >> > > > > > > That should be handled via the attach()/detach() state machine. > > > > > >> In such case, linux need to issue virtio device reset, and wait until > > >> RPU completes the reset and start the device again. The virtio framework > > >> already issues the reset during boot here: > > >> https://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux.git/tree/drivers/virtio/virtio.c?h=for-next#n570 > > >> > > >> However, the virtio_reset implementation for remoteproc_virtio simply > > >> set the status to 0, and doesn't wait for the remote to complete the > > >> reset. Due to this, attach operation becomes successfull, but the rpmsg > > >> channels are not created on the linux side. > > >> > > > > > > I think this situation should be handled in driver code rather than > > > the remoteproc framework. We can consider adding this to the > > > remoteproc framework if/when several platforms implement the same > > > logic. Otherwise I fear we'll bloat the framework with something that > > > isn't generic. > > > > > > > Hi Mathieu, > > > > The previous patch sent in this matter was doing the same: > > https://lore.kernel.org/linux-remoteproc/[email protected]/ > > > > I think this is a much better approach. That said, I would really like to see > something like wait_for_completion_timeout() being used rather than > usleep_range(). >
Thinking back on this, function wait_event_timeout() would be a better choice. > > If you are okay, can I resend it ? I think if that is accepted then we > > don't need this patch atleast for now. > > > > Thank You, > > Tanmay > > > > >> This patch solves this issue. It changes the reset mechanism while > > >> maintaining the backward compatibility for old way of reseting the > > >> device. > > >> > > >> I had sent a different patch regarding this before: > > >> https://lore.kernel.org/linux-remoteproc/[email protected]/ > > >> > > >> Old patch was rejected because we decided to modify the reset mechanism > > >> instead: > > >> https://lists.openampproject.org/archives/list/[email protected]/thread/DDIFUMGQQ2R7CQZJHK7EB6UDO3ISAAVU/ > > >> > > >> Thank You, > > >> Tanmay > > >> > > >> > > >>>> > > >>>> I think timeout mechanism is better for AMP systems over waiting > > >>>> forever > > >>>> for remote to clear the status. > > >>>> > > >>>> Thanks, > > >>>> Tanmay > > >>>> > > >>>> > > >>>>>> + } else { > > >>>>>> + /* back compatible for RSC_VDEV type of rsc vdev */ > > >>>>>> + rsc->status = 0; > > >>>>>> + } > > >>>>>> + dev_info(&vdev->dev, "reset !\n"); > > >>>>>> } > > >>>>>> > > >>>>>> /* provide the vdev features as retrieved from the firmware */ > > >>>>>> @@ -469,6 +506,9 @@ static int rproc_remove_virtio_dev(struct device > > >>>>>> *dev, void *data) > > >>>>>> { > > >>>>>> struct virtio_device *vdev = dev_to_virtio(dev); > > >>>>>> > > >>>>>> + /* reset virtio device before unregister */ > > >>>>>> + virtio_reset_device(vdev); > > >>>>>> + > > >>>>> > > >>>>> Regardless of this feature, I think it is wise to reset the device > > >>>>> before > > >>>>> unregistering with the virtio subsystem. > > >>>>> > > >>>> > > >>>> Agreed. I intend to keep this. > > >>>> > > >>>>> Thanks, > > >>>>> Mathieu > > >>>>> > > >>>>>> unregister_virtio_device(vdev); > > >>>>>> return 0; > > >>>>>> } > > >>>>>> diff --git a/include/linux/rsc_table.h b/include/linux/rsc_table.h > > >>>>>> index 71b60125310e..2398a6d7033e 100644 > > >>>>>> --- a/include/linux/rsc_table.h > > >>>>>> +++ b/include/linux/rsc_table.h > > >>>>>> @@ -66,6 +66,8 @@ struct fw_rsc_hdr { > > >>>>>> * the remote processor will be writing logs. > > >>>>>> * @RSC_VDEV: declare support for a virtio device, and serve > > >>>>>> as its > > >>>>>> * virtio header. > > >>>>>> + * @RSC_VDEV_V2: declare support for a virtio device whose reset > > >>>>>> request is > > >>>>>> + * encoded in the virtio status byte. > > >>>>>> * @RSC_LAST: just keep this one at the end of standard > > >>>>>> resources > > >>>>>> * @RSC_VENDOR_START: start of the vendor specific resource > > >>>>>> types range > > >>>>>> * @RSC_VENDOR_END: end of the vendor specific resource types > > >>>>>> range > > >>>>>> @@ -83,7 +85,8 @@ enum fw_resource_type { > > >>>>>> RSC_DEVMEM = 1, > > >>>>>> RSC_TRACE = 2, > > >>>>>> RSC_VDEV = 3, > > >>>>>> - RSC_LAST = 4, > > >>>>>> + RSC_VDEV_V2 = 4, > > >>>>>> + RSC_LAST = 5, > > >>>>>> RSC_VENDOR_START = 128, > > >>>>>> RSC_VENDOR_END = 512, > > >>>>>> }; > > >>>>>> > > >>>>>> base-commit: d4d61a4b0a52e8f3cdb3e1578602850a3452ec3e > > >>>>>> -- > > >>>>>> 2.43.0 > > >>>>>> > > >>>> > > >> > >
