hw/arm/imx8mp-evk: Add KVM support

Allows the imx8mp-evk machine to run guests with KVM acceleration.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-id: 20251101120130.236721-2-shentey@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

docs/system/arm/imx8mp-evk.rst

@@ -60,3 +60,22 @@ Now that everything is prepared the machine can be started as follows:
       -dtb imx8mp-evk.dtb \
       -append "root=/dev/mmcblk2p2" \
       -drive file=sdcard.img,if=sd,bus=2,format=raw,id=mmcblk2
+
+
+KVM Acceleration
+----------------
+
+To enable hardware-assisted acceleration via KVM, append
+``-accel kvm -cpu host`` to the command line. While this speeds up performance
+significantly, be aware of the following limitations:
+
+* The ``imx8mp-evk`` machine is not included under the "virtualization use case"
+  of :doc:`QEMU's security policy </system/security>`. This means that you
+  should not trust that it can contain malicious guests, whether it is run
+  using TCG or KVM. If you don't trust your guests and you're relying on QEMU to
+  be the security boundary, you want to choose another machine such as ``virt``.
+* Rather than Cortex-A53 CPUs, the same CPU type as the host's will be used.
+  This is a limitation of KVM and may not work with guests with a tight
+  dependency on Cortex-A53.
+* No EL2 and EL3 exception levels are available which is also a KVM limitation.
+  Direct kernel boot should work but running U-Boot, TF-A, etc. won't succeed.

hw/arm/Kconfig

@@ -622,7 +622,8 @@ config FSL_IMX8MP
 config FSL_IMX8MP_EVK
     bool
     default y
-    depends on TCG && AARCH64
+    depends on AARCH64
+    depends on TCG || KVM
     select FSL_IMX8MP
 
 config ARM_SMMUV3

hw/arm/fsl-imx8mp.c

@@ -12,11 +12,13 @@
 #include "system/address-spaces.h"
 #include "hw/arm/bsa.h"
 #include "hw/arm/fsl-imx8mp.h"
-#include "hw/intc/arm_gicv3.h"
 #include "hw/misc/unimp.h"
 #include "hw/boards.h"
+#include "system/kvm.h"
 #include "system/system.h"
+#include "target/arm/cpu.h"
 #include "target/arm/cpu-qom.h"
+#include "target/arm/kvm_arm.h"
 #include "qapi/error.h"
 #include "qobject/qlist.h"
 
@@ -193,15 +195,15 @@ static void fsl_imx8mp_init(Object *obj)
 {
     MachineState *ms = MACHINE(qdev_get_machine());
     FslImx8mpState *s = FSL_IMX8MP(obj);
+    const char *cpu_type = ms->cpu_type ?: ARM_CPU_TYPE_NAME("cortex-a53");
     int i;
 
     for (i = 0; i < MIN(ms->smp.cpus, FSL_IMX8MP_NUM_CPUS); i++) {
         g_autofree char *name = g_strdup_printf("cpu%d", i);
-        object_initialize_child(obj, name, &s->cpu[i],
-                                ARM_CPU_TYPE_NAME("cortex-a53"));
+        object_initialize_child(obj, name, &s->cpu[i], cpu_type);
     }
 
-    object_initialize_child(obj, "gic", &s->gic, TYPE_ARM_GICV3);
+    object_initialize_child(obj, "gic", &s->gic, gicv3_class_name());
 
     object_initialize_child(obj, "ccm", &s->ccm, TYPE_IMX8MP_CCM);
 
@@ -274,7 +276,8 @@ static void fsl_imx8mp_realize(DeviceState *dev, Error **errp)
     /* CPUs */
     for (i = 0; i < ms->smp.cpus; i++) {
         /* On uniprocessor, the CBAR is set to 0 */
-        if (ms->smp.cpus > 1) {
+        if (ms->smp.cpus > 1 &&
+                object_property_find(OBJECT(&s->cpu[i]), "reset-cbar")) {
             object_property_set_int(OBJECT(&s->cpu[i]), "reset-cbar",
                                     fsl_imx8mp_memmap[FSL_IMX8MP_GIC_DIST].addr,
                                     &error_abort);
@@ -286,6 +289,16 @@ static void fsl_imx8mp_realize(DeviceState *dev, Error **errp)
         object_property_set_int(OBJECT(&s->cpu[i]), "cntfrq", 8000000,
                                 &error_abort);
 
+        if (object_property_find(OBJECT(&s->cpu[i]), "has_el2")) {
+            object_property_set_bool(OBJECT(&s->cpu[i]), "has_el2",
+                                     !kvm_enabled(), &error_abort);
+        }
+
+        if (object_property_find(OBJECT(&s->cpu[i]), "has_el3")) {
+            object_property_set_bool(OBJECT(&s->cpu[i]), "has_el3",
+                                     !kvm_enabled(), &error_abort);
+        }
+
         if (i) {
             /*
              * Secondary CPUs start in powered-down state (and can be
@@ -304,6 +317,7 @@ static void fsl_imx8mp_realize(DeviceState *dev, Error **errp)
     {
         SysBusDevice *gicsbd = SYS_BUS_DEVICE(&s->gic);
         QList *redist_region_count;
+        bool pmu = object_property_get_bool(OBJECT(first_cpu), "pmu", NULL);
 
         qdev_prop_set_uint32(gicdev, "num-cpu", ms->smp.cpus);
         qdev_prop_set_uint32(gicdev, "num-irq",
@@ -360,6 +374,16 @@ static void fsl_imx8mp_realize(DeviceState *dev, Error **errp)
                                qdev_get_gpio_in(cpudev, ARM_CPU_VIRQ));
             sysbus_connect_irq(gicsbd, i + 3 * ms->smp.cpus,
                                qdev_get_gpio_in(cpudev, ARM_CPU_VFIQ));
+
+            if (kvm_enabled()) {
+                if (pmu) {
+                    assert(arm_feature(&s->cpu[i].env, ARM_FEATURE_PMU));
+                    if (kvm_irqchip_in_kernel()) {
+                        kvm_arm_pmu_set_irq(&s->cpu[i], VIRTUAL_PMU_IRQ);
+                    }
+                    kvm_arm_pmu_init(&s->cpu[i]);
+                }
+            }
         }
     }
 

hw/arm/imx8mp-evk.c

@@ -13,6 +13,7 @@
 #include "hw/arm/machines-qom.h"
 #include "hw/boards.h"
 #include "hw/qdev-properties.h"
+#include "system/kvm.h"
 #include "system/qtest.h"
 #include "qemu/error-report.h"
 #include "qapi/error.h"
@@ -94,12 +95,22 @@ static void imx8mp_evk_init(MachineState *machine)
     }
 }
 
+static const char *imx8mp_evk_get_default_cpu_type(const MachineState *ms)
+{
+    if (kvm_enabled()) {
+        return ARM_CPU_TYPE_NAME("host");
+    }
+
+    return ARM_CPU_TYPE_NAME("cortex-a53");
+}
+
 static void imx8mp_evk_machine_init(MachineClass *mc)
 {
     mc->desc = "NXP i.MX 8M Plus EVK Board";
     mc->init = imx8mp_evk_init;
     mc->max_cpus = FSL_IMX8MP_NUM_CPUS;
     mc->default_ram_id = "imx8mp-evk.ram";
+    mc->get_default_cpu_type = imx8mp_evk_get_default_cpu_type;
 }
 
 DEFINE_MACHINE_AARCH64("imx8mp-evk", imx8mp_evk_machine_init)