Drivers: hv: balloon: account for vmbus packet header in max_pkt_size

Commit adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V
out of the ring buffer") introduced a notion of maximum packet size in
vmbus channel and used that size to initialize a buffer holding all
incoming packet along with their vmbus packet header. hv_balloon uses
the default maximum packet size VMBUS_DEFAULT_MAX_PKT_SIZE which matches
its maximum message size, however vmbus_open expects this size to also
include vmbus packet header. This leads to 4096 bytes
dm_unballoon_request messages being truncated to 4080 bytes. When the
driver tries to read next packet it starts from a wrong read_index,
receives garbage and prints a lot of "Unhandled message: type:
<garbage>" in dmesg.

Allocate the buffer with HV_HYP_PAGE_SIZE more bytes to make room for
the header.

Fixes: adae1e931acd ("Drivers: hv: vmbus: Copy packets sent by Hyper-V out of the ring buffer")
Suggested-by: Michael Kelley (LINUX) <[email protected]>
Suggested-by: Andrea Parri (Microsoft) <[email protected]>
Signed-off-by: Yanming Liu <[email protected]>
Reviewed-by: Michael Kelley <[email protected]>
Reviewed-by: Andrea Parri (Microsoft) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Wei Liu <[email protected]>

0 files changed, 0 insertions, 0 deletions