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[Qemu-devel] [RFC PATCH v0] ppc: Force CPU threads count to be a power o
From: |
Bharata B Rao |
Subject: |
[Qemu-devel] [RFC PATCH v0] ppc: Force CPU threads count to be a power of 2. |
Date: |
Tue, 4 Mar 2014 10:32:54 +0530 |
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 <address@hidden>
---
target-ppc/translate_init.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index 445c360..f3eff5e 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -18,6 +18,7 @@
* License along with this library; if not, see <http://www.gnu.org/licenses/>.
*/
+#include <math.h>
#include "disas/bfd.h"
#include "exec/gdbstub.h"
#include <sysemu/kvm.h>
@@ -7979,6 +7980,7 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error
**errp)
Error *local_err = NULL;
#if !defined(CONFIG_USER_ONLY)
int max_smt = kvm_enabled() ? kvmppc_smt_threads() : 1;
+ int threads_shift;
#endif
#if !defined(CONFIG_USER_ONLY)
@@ -7987,6 +7989,12 @@ static void ppc_cpu_realizefn(DeviceState *dev, Error
**errp)
max_smt, kvm_enabled() ? "KVM" : "TCG");
return;
}
+ threads_shift = log2(smp_threads);
+ if (smp_threads != (1 << threads_shift)) {
+ error_setg(errp, "Cannot support %d threads on PPC with %s",
+ smp_threads, kvm_enabled() ? "KVM" : "TCG");
+ return;
+ }
#endif
if (kvm_enabled()) {
--
1.7.11.7
- [Qemu-devel] [RFC PATCH v0] ppc: Force CPU threads count to be a power of 2.,
Bharata B Rao <=