hw: add .min_cpus and .default_cpus fields to machine_class

max_cpus needs to be an upper bound on the number of vCPUs
initialized; otherwise TCG region initialization breaks.

Some boards initialize a hard-coded number of vCPUs, which is not
captured by the global max_cpus and therefore breaks TCG initialization.
Fix it by adding the .min_cpus field to machine_class.

This commit also changes some user-facing behaviour: we now die if
-smp is below this hard-coded vCPU minimum instead of silently
ignoring the passed -smp value (sometimes announcing this by printing
a warning). However, the introduction of .default_cpus lessens the
likelihood that users will notice this: if -smp isn't set, we now
assign the value in .default_cpus to both smp_cpus and max_cpus. IOW,
if a user does not set -smp, they always get a correct number of vCPUs.

This change fixes 3468b59 ("tcg: enable multiple TCG contexts in
softmmu", 2017-10-24), which broke TCG initialization for some
ARM boards.

Fixes: 3468b59e18b179bc63c7ce934de912dfa9596122
Reported-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Message-id: 1510343626-25861-6-git-send-email-cota@braap.org
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Emilio G. Cota <cota@braap.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 4 insertions, 8 deletions

diff --git a/hw/arm/exynos4_boards.c b/hw/arm/exynos4_boards.c
index f1441ec6cf..750162cc95 100644
--- a/hw/arm/exynos4_boards.c
+++ b/hw/arm/exynos4_boards.c
@@ -27,7 +27,6 @@
 #include "qemu-common.h"
 #include "cpu.h"
 #include "sysemu/sysemu.h"
-#include "sysemu/qtest.h"
 #include "hw/sysbus.h"
 #include "net/net.h"
 #include "hw/arm/arm.h"
@@ -129,13 +128,6 @@ exynos4_boards_init_common(MachineState *machine,
                            Exynos4BoardType board_type)
 {
     Exynos4BoardState *s = g_new(Exynos4BoardState, 1);
-    MachineClass *mc = MACHINE_GET_CLASS(machine);
-
-    if (smp_cpus != EXYNOS4210_NCPUS && !qtest_enabled()) {
-        error_report("%s board supports only %d CPU cores, ignoring smp_cpus"
-                     " value",
-                     mc->name, EXYNOS4210_NCPUS);
-    }
 
     exynos4_board_binfo.ram_size = exynos4_board_ram_size[board_type];
     exynos4_board_binfo.board_id = exynos4_board_id[board_type];
@@ -189,6 +181,8 @@ static void nuri_class_init(ObjectClass *oc, void *data)
     mc->desc = "Samsung NURI board (Exynos4210)";
     mc->init = nuri_init;
     mc->max_cpus = EXYNOS4210_NCPUS;
+    mc->min_cpus = EXYNOS4210_NCPUS;
+    mc->default_cpus = EXYNOS4210_NCPUS;
     mc->ignore_memory_transaction_failures = true;
 }
 
@@ -205,6 +199,8 @@ static void smdkc210_class_init(ObjectClass *oc, void *data)
     mc->desc = "Samsung SMDKC210 board (Exynos4210)";
     mc->init = smdkc210_init;
     mc->max_cpus = EXYNOS4210_NCPUS;
+    mc->min_cpus = EXYNOS4210_NCPUS;
+    mc->default_cpus = EXYNOS4210_NCPUS;
     mc->ignore_memory_transaction_failures = true;
 }