Commit 5ec83c73 authored by Bharata B Rao's avatar Bharata B Rao Committed by Andreas Färber
Browse files

target-ppc: Force CPU threads count to be a power of 2 



PowerPC kernel expects the number of SMT threads in a core to be a power
of 2. Since QEMU doesn't enforce this, it leads to an early guest kernel
crash if invalid threads count is specified.

Prevent this crash and make it a graceful exit from QEMU itself by
validating the user-supplied threads count.

Signed-off-by: default avatarBharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: default avatarEric Blake <eblake@redhat.com>
Reviewed-by: default avatarStewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: default avatarAndreas Färber <afaerber@suse.de>
parent a80172a4

target-ppc/translate_init.c

+6 −0
Original line number Diff line number Diff line
@@ -7848,6 +7848,12 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error **errp) 
                   max_smt, kvm_enabled() ? "KVM" : "TCG");

        return;

    }

    if (!is_power_of_2(smp_threads)) {

        error_setg(errp, "Cannot support %d threads on PPC with %s, "

                   "threads count must be a power of 2.",

                   smp_threads, kvm_enabled() ? "KVM" : "TCG");

        return;

    }



    cpu->cpu_dt_id = (cs->cpu_index / smp_threads) * max_smt

        + (cs->cpu_index % smp_threads);