[PATCH v2] hw/arm: add pvpanic mmio device for arm

[xpahos@gmail.com]

From: Alexander Gryanko <xpahos@gmail.com>

Currently, pvpanic is available in three device types: ISA,
MMIO, and PCI. For early stages of system initialisation
before PCI enumeration, only ISA and MMIO are suitable.
ISA is specific to the x86 platform; only MMIO devices
can be used for ARM. It is not possible to specify a
device as on the x86 platform (-device pvpanic); the
only possible way is to add an MMIO device to the dtb,
which can be implemented by manually adding new functions
to the QEMU code, as was done in the VMApple implementation.

Signed-off-by: Alexander Gryanko <xpahos@gmail.com>
---
 hw/arm/virt.c         | 26 ++++++++++++++++++++++++++
 include/hw/arm/virt.h |  1 +
 2 files changed, 27 insertions(+)

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 02209fadcf..78e466f935 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -39,6 +39,7 @@
 #include "hw/arm/virt.h"
 #include "hw/block/flash.h"
 #include "hw/display/ramfb.h"
+#include "hw/misc/pvpanic.h"
 #include "net/net.h"
 #include "system/device_tree.h"
 #include "system/numa.h"
@@ -182,6 +183,7 @@ static const MemMapEntry base_memmap[] = {
     [VIRT_UART0] =              { 0x09000000, 0x00001000 },
     [VIRT_RTC] =                { 0x09010000, 0x00001000 },
     [VIRT_FW_CFG] =             { 0x09020000, 0x00000018 },
+    [VIRT_PVPANIC] =            { 0x09021000, 0x00000002 },
     [VIRT_GPIO] =               { 0x09030000, 0x00001000 },
     [VIRT_UART1] =              { 0x09040000, 0x00001000 },
     [VIRT_SMMU] =               { 0x09050000, SMMU_IO_LEN },
@@ -276,6 +278,28 @@ static bool ns_el2_virt_timer_present(void)
         arm_feature(env, ARM_FEATURE_EL2) && cpu_isar_feature(aa64_vh, cpu);
 }
 
+static void create_pvpanic(VirtMachineState *vms)
+{
+    char *nodename;
+    MachineState *ms = MACHINE(vms);
+    DeviceState *dev = qdev_new(TYPE_PVPANIC_MMIO_DEVICE);
+    SysBusDevice *s = SYS_BUS_DEVICE(dev);
+
+    hwaddr base = vms->memmap[VIRT_PVPANIC].base;
+    hwaddr size = vms->memmap[VIRT_PVPANIC].size;
+
+    sysbus_realize_and_unref(s, &error_fatal);
+    sysbus_mmio_map(s, 0, base);
+
+    nodename = g_strdup_printf("/pvpanic@%" PRIx64, base);
+    qemu_fdt_add_subnode(ms->fdt, nodename);
+    qemu_fdt_setprop_string(ms->fdt, nodename, "compatible",
+                            "qemu,pvpanic-mmio");
+    qemu_fdt_setprop_sized_cells(ms->fdt, nodename, "reg",
+                                 2, base, 2, size);
+    g_free(nodename);
+}
+
 static void create_fdt(VirtMachineState *vms)
 {
     MachineState *ms = MACHINE(vms);
@@ -2498,6 +2522,8 @@ static void machvirt_init(MachineState *machine)
     create_pcie(vms);
     create_cxl_host_reg_region(vms);
 
+    create_pvpanic(vms);
+
     if (has_ged && aarch64 && firmware_loaded && virt_is_acpi_enabled(vms)) {
         vms->acpi_dev = create_acpi_ged(vms);
     } else {
diff --git a/include/hw/arm/virt.h b/include/hw/arm/virt.h
index ea2cff05b0..39bf07c9c1 100644
--- a/include/hw/arm/virt.h
+++ b/include/hw/arm/virt.h
@@ -81,6 +81,7 @@ enum {
     VIRT_NVDIMM_ACPI,
     VIRT_PVTIME,
     VIRT_ACPI_PCIHP,
+    VIRT_PVPANIC,
     VIRT_LOWMEMMAP_LAST,
 };
 

---
base-commit: bd6aa0d1e59d71218c3eee055bc8d222c6e1a628
change-id: 20251005-arm-pvpanic-8e3e8fd05e95

Best regards,
-- 
Alexander Gryanko <xpahos@gmail.com>