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

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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: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Andreas Färber <afaerber@suse.de>
This commit is contained in:
Bharata B Rao 2014-03-05 14:02:36 +05:30 committed by Andreas Färber
parent a80172a476
commit 5ec83c73e5
1 changed files with 6 additions and 0 deletions
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6
target-ppc/translate_init.c
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@ -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);