On Tue, Jan 04, 2022 at 09:15:27AM -0800, Dave Hansen wrote: > > From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > > == Problem == > > Nathan Chancellor reported an oops when aceessing the > 'sgx_total_bytes' sysfs file: > > https://lore.kernel.org/all/YbzhBrimHGGpddDM@archlinux-ax161/ > > The sysfs output code accesses the sgx_numa_nodes[] array > unconditionally. However, this array is allocated during SGX > initialization, which only occurs on systems where SGX is > supported. > > If the sysfs file is accessed on systems without SGX support, > sgx_numa_nodes[] is NULL and an oops occurs. > > == Solution == > > To fix this, hide the entire nodeX/x86/ attribute group on > systems without SGX support using the ->is_visible attribute > group callback. > > Unfortunately, SGX is initialized via a device_initcall() which > occurs _after_ the ->is_visible() callback. Instead of moving > SGX initialization earlier, call sysfs_update_group() during > SGX initialization to update the group visiblility. > > This update requires moving the SGX sysfs code earlier in > sgx/main.c. There are no code changes other than the addition of > arch_update_sysfs_visibility() and a minor whitespace fixup to > arch_node_attr_is_visible() which checkpatch caught. > > Fixes: 50468e431335 ("x86/sgx: Add an attribute for the amount of SGX memory in a NUMA node") > Reported-by: Nathan Chancellor <nathan@xxxxxxxxxx> > Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> > CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > Cc: Jarkko Sakkinen <jarkko@xxxxxxxxxx> > Cc: linux-sgx@xxxxxxxxxxxxxxx > Cc: x86@xxxxxxxxxx > --- > > b/arch/x86/kernel/cpu/sgx/main.c | 65 ++++++++++++++++++++++++++++----------- > 1 file changed, 47 insertions(+), 18 deletions(-) Reviewed-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
