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(). > 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 > >>>>>> > >>>> > >> >
