hv_hypercall_pg page permissios

[Christoph Hellwig]

Hi all,

The x86 Hyper-V hypercall page (hv_hypercall_pg) is the only allocation
in the kernel using __vmalloc with exectutable persmissions, and the
only user of PAGE_KERNEL_RX.  Is there any good reason it needs to
be readable?  Otherwise we could use vmalloc_exec and kill off
PAGE_KERNEL_RX.  Note that before 372b1e91343e6 ("drivers: hv: Turn off
write permission on the hypercall page") it was even mapped writable..