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c9c4c070e0
Prevent calling roundup_pow_of_two() with value of 0 as it causes the below UBSAN note. Move this code and its few extra related lines to be called only when it's really applicable. UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 15 PID: 1639 Comm: live_migration Not tainted 6.1.0-rc4 #1116 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x45/0x59 ubsan_epilogue+0x5/0x36 __ubsan_handle_shift_out_of_bounds.cold+0x61/0xef ? lock_is_held_type+0x98/0x110 ? rcu_read_lock_sched_held+0x3f/0x70 mlx5vf_create_rc_qp.cold+0xe4/0xf2 [mlx5_vfio_pci] mlx5vf_start_page_tracker+0x769/0xcd0 [mlx5_vfio_pci] vfio_device_fops_unl_ioctl+0x63f/0x700 [vfio] __x64_sys_ioctl+0x433/0x9a0 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd </TASK> Fixes: 79c3cf279926 ("vfio/mlx5: Init QP based resources for dirty tracking") Signed-off-by: Yishai Hadas <yishaih@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Link: https://lore.kernel.org/r/20230108154427.32609-2-yishaih@nvidia.com Signed-off-by: Alex Williamson <alex.williamson@redhat.com>