On 11/15/2025 2:27 PM, Naman Jain wrote:
From: Long Li <[email protected]> Hyper-V may offer a non latency sensitive device with subchannels without monitor bit enabled. The decision is entirely on the Hyper-V host not configurable within guest. When a device has subchannels, also signal events for the subchannel if its monitor bit is disabled. This patch also removes the memory barrier when monitor bit is enabled as it is not necessary. The memory barrier is only needed between setting up interrupt mask and calling vmbus_set_event() when monitor bit is disabled. This is a backport of the upstream commit d062463edf17 ("uio_hv_generic: Set event for all channels on the device") with minor modifications to resolve merge conflicts. Original change was not a fix, but it needs to be backported to fix a NULL pointer crash resulting from missing interrupt mask setting. Commit 37bd91f22794 ("uio_hv_generic: Let userspace take care of interrupt mask") removed the default setting of interrupt_mask for channels (including subchannels) in the uio_hv_generic driver, as it relies on the user space to take care of managing it. This approach works fine when user space can control this setting using the irqcontrol interface provided for uio devices. Support for setting the interrupt mask through this interface for subchannels came only after commit d062463edf17 ("uio_hv_generic: Set event for all channels on the device"). On older kernels, this change is not present. With uio_hv_generic no longer setting the interrupt_mask, and userspace not having the capability to set it, it remains unset, and interrupts can come for the subchannels, which can result in a crash in hv_uio_channel_cb. Backport the change to older kernels, where this change was not present, to allow userspace to set the interrupt mask properly for subchannels. Additionally, this patch also adds certain checks for primary vs subchannels in the hv_uio_channel_cb, which can gracefully handle these two cases and prevent the NULL pointer crashes. Signed-off-by: Long Li <[email protected]> Reviewed-by: Michael Kelley <[email protected]> Reviewed-by: Saurabh Sengar <[email protected]> Fixes: 37bd91f22794 ("uio_hv_generic: Let userspace take care of interrupt mask")
Sorry for missing this, please add Closes tag, if possible before merging. Closes: https://bugs.debian.org/1120602 I have kept it in the other patch for 6.6 and prior kernels. Regards, Naman
Cc: <[email protected]> # 6.12.x Signed-off-by: Naman Jain <[email protected]> ---
Regards, Naman
