[Qemu-devel] [PATCH v3] spapr: set vsmt to MAX(8, smp_threads)

[Laurent Vivier]

We ignore silently the value of smp_threads when we set
the default VSMT value, and if smp_threads is greater than VSMT
kernel is going into trouble later.

Fixes: 8904e5a750
("spapr: Adjust default VSMT value for better migration compatibility")

Signed-off-by: Laurent Vivier <address@hidden>
---

Notes:
    v3: use MAX(8, smp_threads) and let KVM to return an error
        if nb_threads is too big
        update subject to reflect the change
    
    v2: display a specific error message when the default VSMT is used
        fix subject

 hw/ppc/spapr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 32a876be56..c8a1eefa17 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -2310,7 +2310,7 @@ static void spapr_set_vsmt_mode(sPAPRMachineState *spapr, 
Error **errp)
          * the value that we'd get with KVM on POWER8, the
          * overwhelmingly common case in production systems.
          */
-        spapr->vsmt = 8;
+        spapr->vsmt = MAX(8, smp_threads);
     }
 
     /* KVM: If necessary, set the SMT mode: */
-- 
2.14.3