4.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Michael Kelley <mikelley@xxxxxxxxxxxxx> commit 13b9abfc92be7c4454bff912021b9f835dea6e15 upstream. Extend the disabling of preemption to include the hypercall so that another thread can't get the CPU and corrupt the per-cpu page used for hypercall arguments. Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hv/hv.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/drivers/hv/hv.c +++ b/drivers/hv/hv.c @@ -82,10 +82,15 @@ int hv_post_message(union hv_connection_ aligned_msg->message_type = message_type; aligned_msg->payload_size = payload_size; memcpy((void *)aligned_msg->payload, payload, payload_size); - put_cpu_ptr(hv_cpu); status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL); + /* Preemption must remain disabled until after the hypercall + * so some other thread can't get scheduled onto this cpu and + * corrupt the per-cpu post_msg_page + */ + put_cpu_ptr(hv_cpu); + return status & 0xFFFF; }