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Tsirkin" Cc: "Kirill A. Shutemov" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Zhenzhong Duan , virtualization@lists.linux.dev, linux-kernel@vger.kernel.org References: <20240808075141.3433253-1-kirill.shutemov@linux.intel.com> <20250203094700-mutt-send-email-mst@kernel.org> <7cee3c9e-515e-41de-a15c-04c7591e83eb@redhat.com> <6bce0f4c-636f-456b-ab21-4a25d3dc8803@redhat.com> Content-Language: en-US From: "Ning, Hongyu" In-Reply-To: <6bce0f4c-636f-456b-ab21-4a25d3dc8803@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2025/2/6 16:59, Eric Auger wrote: > Hi, > > On 2/4/25 12:46 PM, Eric Auger wrote: >> Hi, >> >> On 2/3/25 3:48 PM, Michael S. Tsirkin wrote: >>> On Fri, Jan 31, 2025 at 10:53:15AM +0100, Eric Auger wrote: >>>> Hi Kirill, Michael >>>> >>>> On 8/8/24 9:51 AM, Kirill A. Shutemov wrote: >>>>> Hongyu reported a hang on kexec in a VM. QEMU reported invalid memory >>>>> accesses during the hang. >>>>> >>>>> Invalid read at addr 0x102877002, size 2, region '(null)', reason: rejected >>>>> Invalid write at addr 0x102877A44, size 2, region '(null)', reason: rejected >>>>> ... >>>>> >>>>> It was traced down to virtio-console. Kexec works fine if virtio-console >>>>> is not in use. >>>>> >>>>> Looks like virtio-console continues to write to the MMIO even after >>>>> underlying virtio-pci device is removed. >>>>> >>>>> The problem can be mitigated by removing all virtio devices on virtio >>>>> bus shutdown. >>>>> >>>>> Signed-off-by: Kirill A. Shutemov >>>>> Reported-by: Hongyu Ning >>>> >>>> Gentle ping on that patch that seems to have fallen though the cracks. >>>> >>>> I think this fix is really needed. I have another test case with a >>>> rebooting guest exposed with virtio-net (backed by vhost-net) and >>>> viommu. Since there is currently no shutdown for the virtio-net, on >>>> reboot, the IOMMU is disabled through the native_machine_shutdown()/ >>>> x86_platform.iommu_shutdown() while the virtio-net is still alive. >>>> >>>> Normally device_shutdown() should call virtio-net shutdown before the >>>> IOMMU tear down and we wouldn't see any spurious transactions after >>>> iommu shutdown. >>>> >>>> With that fix, the above test case is fixed and I do not see spurious >>>> vhost IOTLB miss spurious requests. >>>> >>>> For more details, see qemu thread ([PATCH] hw/virtio/vhost: Disable >>>> IOTLB callbacks when IOMMU gets disabled, >>>> https://lore.kernel.org/all/20250120173339.865681-1-eric.auger@redhat.com/) >>>> >>>> >>>> Reviewed-by: Eric Auger >>>> Tested-by: Eric Auger >>>> >>>> Thanks >>>> >>>> Eric >>>> >>>>> --- >>>>> drivers/virtio/virtio.c | 10 ++++++++++ >>>>> 1 file changed, 10 insertions(+) >>>>> >>>>> diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c >>>>> index a9b93e99c23a..6c2f908eb22c 100644 >>>>> --- a/drivers/virtio/virtio.c >>>>> +++ b/drivers/virtio/virtio.c >>>>> @@ -356,6 +356,15 @@ static void virtio_dev_remove(struct device *_d) >>>>> of_node_put(dev->dev.of_node); >>>>> } >>>>> >>>>> +static void virtio_dev_shutdown(struct device *_d) >>>>> +{ >>>>> + struct virtio_device *dev = dev_to_virtio(_d); >>>>> + struct virtio_driver *drv = drv_to_virtio(dev->dev.driver); >>>>> + >>>>> + if (drv && drv->remove) >>>>> + drv->remove(dev); >>> >>> >>> I am concerned that full remove is a heavyweight operation. >>> Do not want to slow down reboots even more. >>> How about just doing a reset, instead? >> >> I tested with >> >> static void virtio_dev_shutdown(struct device *_d) >> { >> struct virtio_device *dev = dev_to_virtio(_d); >> >> virtio_reset_device(dev); >> } >> >> >> and it fixes my issue. >> >> Kirill, would that fix you issue too? Hi, sorry for my late response, I synced with Kirill offline and did a retest. The issue is still reproduced on my side, kexec will be stuck in case of "console=hvc0" append in kernel cmdline and even with such patch applied. my kernel code base is 6.14.0-rc2. let me know if any more experiments needed. --- drivers/virtio/virtio.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index ba37665188b5..f9f885d04763 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -395,6 +395,13 @@ static const struct cpumask *virtio_irq_get_affinity(struct device *_d, return dev->config->get_vq_affinity(dev, irq_vec); } +static void virtio_dev_shutdown(struct device *_d) +{ + struct virtio_device *dev = dev_to_virtio(_d); + + virtio_reset_device(dev); +} + static const struct bus_type virtio_bus = { .name = "virtio", .match = virtio_dev_match, @@ -403,6 +410,7 @@ static const struct bus_type virtio_bus = { .probe = virtio_dev_probe, .remove = virtio_dev_remove, .irq_get_affinity = virtio_irq_get_affinity, + .shutdown = virtio_dev_shutdown, }; int __register_virtio_driver(struct virtio_driver *driver, struct module *owner) -- 2.43.0 > gentle ping. > > this also fixes another issue with qemu vSMMU + virtio-scsi-pci. With > the above addition I get rid of spurious warning in qemu on guest reboot. > > qemu-system-aarch64: virtio: zero sized buffers are not allowed > qemu-system-aarch64: vhost vring error in virtqueue 0: Invalid argument (22) > > Would you mind if I respin? > > Thanks > > Eric > > > > >> >> Thanks >> >> Eric >>> >>>>> +} >>>>> + >>>>> static const struct bus_type virtio_bus = { >>>>> .name = "virtio", >>>>> .match = virtio_dev_match, >>>>> @@ -363,6 +372,7 @@ static const struct bus_type virtio_bus = { >>>>> .uevent = virtio_uevent, >>>>> .probe = virtio_dev_probe, >>>>> .remove = virtio_dev_remove, >>>>> + .shutdown = virtio_dev_shutdown, >>>>> }; >>>>> >>>>> int __register_virtio_driver(struct virtio_driver *driver, struct module *owner) >>> >> >