Re: [Qemu-devel] [PATCH v4 05/13] pc: leave max apic_id_limit only in legacy cpu hotplug code

[Eduardo Habkost]

On Tue, Oct 18, 2016 at 01:37:46PM +0200, Igor Mammedov wrote:
> that's enough to make old code that depends on it
> to prevent QEMU starting with more than 255 CPUs.
> 
> Signed-off-by: Igor Mammedov 

Reviewed-by: Eduardo Habkost 

-- 
Eduardo

[Qemu-devel] [PATCH v4 05/13] pc: leave max apic_id_limit only in legacy cpu hotplug code

[Igor Mammedov]

that's enough to make old code that depends on it
to prevent QEMU starting with more than 255 CPUs.

Signed-off-by: Igor Mammedov 
---
v4:
  - keep assert() as it doesn't affect x2APIC cpus (Eduardo)
---
 hw/acpi/cpu_hotplug.c | 7 ++-
 hw/i386/pc.c  | 6 --
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/hw/acpi/cpu_hotplug.c b/hw/acpi/cpu_hotplug.c
index c2ab9b8..f15a240 100644
--- a/hw/acpi/cpu_hotplug.c
+++ b/hw/acpi/cpu_hotplug.c
@@ -15,6 +15,7 @@
 #include "qapi/error.h"
 #include "qom/cpu.h"
 #include "hw/i386/pc.h"
+#include "qemu/error-report.h"
 
 #define CPU_EJECT_METHOD "CPEJ"
 #define CPU_MAT_METHOD "CPMA"
@@ -236,7 +237,11 @@ void build_legacy_cpu_hotplug_aml(Aml *ctx, MachineState 
*machine,
 /* The current AML generator can cover the APIC ID range [0..255],
  * inclusive, for VCPU hotplug. */
 QEMU_BUILD_BUG_ON(ACPI_CPU_HOTPLUG_ID_LIMIT > 256);
-g_assert(pcms->apic_id_limit <= ACPI_CPU_HOTPLUG_ID_LIMIT);
+if (pcms->apic_id_limit > ACPI_CPU_HOTPLUG_ID_LIMIT) {
+error_report("max_cpus is too large. APIC ID of last CPU is %u",
+ pcms->apic_id_limit - 1);
+exit(1);
+}
 
 /* create PCI0.PRES device and its _CRS to reserve CPU hotplug MMIO */
 dev = aml_device("PCI0." stringify(CPU_HOTPLUG_RESOURCE_DEVICE));
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 93ff49c..2045525 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1190,12 +1190,6 @@ void pc_cpus_init(PCMachineState *pcms)
  * This is used for FW_CFG_MAX_CPUS. See comments on bochs_bios_init().
  */
 pcms->apic_id_limit = x86_cpu_apic_id_from_index(max_cpus - 1) + 1;
-if (pcms->apic_id_limit > ACPI_CPU_HOTPLUG_ID_LIMIT) {
-error_report("max_cpus is too large. APIC ID of last CPU is %u",
- pcms->apic_id_limit - 1);
-exit(1);
-}
-
 pcms->possible_cpus = g_malloc0(sizeof(CPUArchIdList) +
 sizeof(CPUArchId) * max_cpus);
 for (i = 0; i < max_cpus; i++) {
-- 
2.7.4