On a Xen dom0 boot, this feature does not behave, and we end up calculating:

num_roots = 1 num_nodes = 2 roots_per_node = 0

This causes a divide-by-zero in the modulus inside the loop.

This change adds a couple of guards for invalid states where we might get a divide-by-zero.

Signed-off-by: Steven Noonan steven@uplinklabs.net Signed-off-by: Ariadne Conill ariadne@ariadne.space CC: Yazen Ghannam yazen.ghannam@amd.com CC: x86@vger.kernel.org CC: stable@vger.kernel.org --- arch/x86/kernel/amd_node.c | 11 +++++++++++ 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kernel/amd_node.c b/arch/x86/kernel/amd_node.c index 3d0a4768d603c..cdc6ba224d4ad 100644 --- a/arch/x86/kernel/amd_node.c +++ b/arch/x86/kernel/amd_node.c @@ -282,6 +282,17 @@ static int __init amd_smn_init(void) return -ENODEV;

num_nodes = amd_num_nodes(); + + if (!num_nodes) + return -ENODEV; + + /* Possibly a virtualized environment (e.g. Xen) where we wi ll get + * roots_per_node=0 if the number of roots is fewer than number of + * nodes + */ + if (num_roots < num_nodes) + return -ENODEV; + amd_roots = kcalloc(num_nodes, sizeof(*amd_roots), GFP_KERNEL); if (!amd_roots) return -ENOMEM;