[RFC,V5,06/30] arm/virt, gicv3: Changes to pre-size GIC with possible vCPUs @machine init

Commit Message

Salil Mehta Oct. 15, 2024, 9:59 a.m. UTC

The GIC must be pre-sized with the possible vCPUs during initialization. This is
essential because:

1. Memory regions and resources associated with GICC/GICR cannot be modified
   (i.e., added, deleted, or changed) once the VM has been initialized.
2. Additionally, the `GIC_TYPER` must be initialized with the `mp_affinity` and
   CPU interface number associations, which cannot be altered after
   initialization.

Co-developed-by: Keqian Zhu <[e-mail]>
Signed-off-by: Keqian Zhu <[e-mail]>
Signed-off-by: Salil Mehta <[e-mail]>
---
 hw/arm/virt.c         | 15 ++++++++-------
 include/hw/arm/virt.h |  2 +-
 2 files changed, 9 insertions(+), 8 deletions(-)

Patch

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 858a19bc8b..b286afc62c 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -769,6 +769,7 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
     const char *gictype;
     int i;
     unsigned int smp_cpus = ms->smp.cpus;
+    unsigned int max_cpus = ms->smp.max_cpus;
     uint32_t nb_redist_regions = 0;
     int revision;
 
@@ -793,7 +794,7 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
     }
     vms->gic = qdev_new(gictype);
     qdev_prop_set_uint32(vms->gic, "revision", revision);
-    qdev_prop_set_uint32(vms->gic, "num-cpu", smp_cpus);
+    qdev_prop_set_uint32(vms->gic, "num-cpu", max_cpus);
     /* Note that the num-irq property counts both internal and external
      * interrupts; there are always 32 of the former (mandated by GIC spec).
      */
@@ -805,7 +806,7 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
     if (vms->gic_version != VIRT_GIC_VERSION_2) {
         QList *redist_region_count;
         uint32_t redist0_capacity = virt_redist_capacity(vms, VIRT_GIC_REDIST);
-        uint32_t redist0_count = MIN(smp_cpus, redist0_capacity);
+        uint32_t redist0_count = MIN(max_cpus, redist0_capacity);
 
         nb_redist_regions = virt_gicv3_redist_region_count(vms);
 
@@ -816,7 +817,7 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
                 virt_redist_capacity(vms, VIRT_HIGH_GIC_REDIST2);
 
             qlist_append_int(redist_region_count,
-                MIN(smp_cpus - redist0_count, redist1_capacity));
+                MIN(max_cpus - redist0_count, redist1_capacity));
         }
         qdev_prop_set_array(vms->gic, "redist-region-count",
                             redist_region_count);
@@ -889,7 +890,7 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
         } else if (vms->virt) {
             qemu_irq irq = qdev_get_gpio_in(vms->gic,
                                             intidbase + ARCH_GIC_MAINT_IRQ);
-            sysbus_connect_irq(gicbusdev, i + 4 * smp_cpus, irq);
+            sysbus_connect_irq(gicbusdev, i + 4 * max_cpus, irq);
         }
 
         qdev_connect_gpio_out_named(cpudev, "pmu-interrupt", 0,
@@ -897,11 +898,11 @@  static void create_gic(VirtMachineState *vms, MemoryRegion *mem)
                                                      + VIRTUAL_PMU_IRQ));
 
         sysbus_connect_irq(gicbusdev, i, qdev_get_gpio_in(cpudev, ARM_CPU_IRQ));
-        sysbus_connect_irq(gicbusdev, i + smp_cpus,
+        sysbus_connect_irq(gicbusdev, i + max_cpus,
                            qdev_get_gpio_in(cpudev, ARM_CPU_FIQ));
-        sysbus_connect_irq(gicbusdev, i + 2 * smp_cpus,
+        sysbus_connect_irq(gicbusdev, i + 2 * max_cpus,
                            qdev_get_gpio_in(cpudev, ARM_CPU_VIRQ));
-        sysbus_connect_irq(gicbusdev, i + 3 * smp_cpus,
+        sysbus_connect_irq(gicbusdev, i + 3 * max_cpus,
                            qdev_get_gpio_in(cpudev, ARM_CPU_VFIQ));
 
         if (vms->gic_version != VIRT_GIC_VERSION_2) {
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index 446c574c0d..362422413c 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -214,7 +214,7 @@  static inline int virt_gicv3_redist_region_count(VirtMachineState *vms)
 
     assert(vms->gic_version != VIRT_GIC_VERSION_2);
 
-    return (MACHINE(vms)->smp.cpus > redist0_capacity &&
+    return (MACHINE(vms)->smp.max_cpus > redist0_capacity &&
             vms->highmem_redists) ? 2 : 1;
 }