qemu-kvm passes numa/SRAT topology information for smp_cpus to SeaBIOS. However SeaBIOS always expects to setup max_cpus number of SRAT cpu entries (MaxCountCPUs variable in build_srat function of Seabios). When qemu-kvm runs with smp_cpus != max_cpus (e.g. -smp 2,maxcpus=4), Seabios will mistakenly use memory SRAT info for setting up CPU SRAT entries for the offline CPUs. Wrong SRAT memory entries are also created. This breaks NUMA in a guest. Fix by setting up SRAT info for max_cpus in qemu-kvm.
Signed-off-by: Vasilis Liaskovitis vasilis.liaskovitis@profitbricks.com --- hw/pc.c | 8 ++++---- vl.c | 2 +- 2 files changed, 5 insertions(+), 5 deletions(-)
diff --git a/hw/pc.c b/hw/pc.c index fb49612..e0a65da 100644 --- a/hw/pc.c +++ b/hw/pc.c @@ -626,9 +626,9 @@ static void *bochs_bios_init(void) * of nodes, one word for each VCPU->node and one word for each node to * hold the amount of memory. */ - numa_fw_cfg = g_malloc0((1 + smp_cpus + nb_numa_nodes) * 8); + numa_fw_cfg = g_malloc0((1 + max_cpus + nb_numa_nodes) * 8); numa_fw_cfg[0] = cpu_to_le64(nb_numa_nodes); - for (i = 0; i < smp_cpus; i++) { + for (i = 0; i < max_cpus; i++) { for (j = 0; j < nb_numa_nodes; j++) { if (node_cpumask[j] & (1 << i)) { numa_fw_cfg[i + 1] = cpu_to_le64(j); @@ -637,10 +637,10 @@ static void *bochs_bios_init(void) } } for (i = 0; i < nb_numa_nodes; i++) { - numa_fw_cfg[smp_cpus + 1 + i] = cpu_to_le64(node_mem[i]); + numa_fw_cfg[max_cpus + 1 + i] = cpu_to_le64(node_mem[i]); } fw_cfg_add_bytes(fw_cfg, FW_CFG_NUMA, (uint8_t *)numa_fw_cfg, - (1 + smp_cpus + nb_numa_nodes) * 8); + (1 + max_cpus + nb_numa_nodes) * 8);
return fw_cfg; } diff --git a/vl.c b/vl.c index aeed54a..a3ae262 100644 --- a/vl.c +++ b/vl.c @@ -3410,7 +3410,7 @@ int main(int argc, char **argv, char **envp) * real machines which also use this scheme. */ if (i == nb_numa_nodes) { - for (i = 0; i < smp_cpus; i++) { + for (i = 0; i < max_cpus; i++) { node_cpumask[i % nb_numa_nodes] |= 1 << i; } }