Drivers: hv: Introduce per-cpu event ring tail

Add a pointer hv_synic_eventring_tail to track the tail pointer for the
SynIC event ring buffer for each SINT.

This will be used by the mshv driver, but must be tracked independently
since the driver module could be removed and re-inserted.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Link: https://lore.kernel.org/r/1741980536-3865-8-git-send-email-nunodasneves@linux.microsoft.com


Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1741980536-3865-8-git-send-email-nunodasneves@linux.microsoft.com>