KVM: PPC: Book3S: Suppress failed alloc warning in H_COPY_TOFROM_GUEST

Browse source

H_COPY_TOFROM_GUEST is an hcall for an upper level VM to access its nested
VMs memory. The userspace can trigger WARN_ON_ONCE(!(gfp & __GFP_NOWARN))
in __alloc_pages() by constructing a tiny VM which only does
H_COPY_TOFROM_GUEST with a too big GPR9 (number of bytes to copy).

This silences the warning by adding __GFP_NOWARN.

Spotted by syzkaller.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210901084550.1658699-1-aik@ozlabs.ru

...

This commit is contained in:

Alexey Kardashevskiy 2021-09-01 18:45:50 +10:00 • committed by Michael Ellerman

parent 511d25d6b7

commit 792020907b

1 changed files with 1 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

2

arch/powerpc/kvm/book3s_hv_nested.c

View file