[PATCH qemu v16] spapr: Implement Open Firmware client interface

* [PATCH qemu v16] spapr: Implement Open Firmware client interface
@ 2021-03-23  2:58 Alexey Kardashevskiy
  2021-03-25  2:52 ` David Gibson
  0 siblings, 1 reply; 7+ messages in thread
From: Alexey Kardashevskiy @ 2021-03-23  2:58 UTC (permalink / raw)
  To: qemu-devel; +Cc: Alexey Kardashevskiy, qemu-ppc, Greg Kurz, David Gibson

The PAPR platform which describes an OS environment that's presented by
a combination of a hypervisor and firmware. The features it specifies
require collaboration between the firmware and the hypervisor.

Since the beginning, the runtime component of the firmware (RTAS) has
been implemented as a 20 byte shim which simply forwards it to
a hypercall implemented in qemu. The boot time firmware component is
SLOF - but a build that's specific to qemu, and has always needed to be
updated in sync with it. Even though we've managed to limit the amount
of runtime communication we need between qemu and SLOF, there's some,
and it has become increasingly awkward to handle as we've implemented
new features.

This implements a boot time OF client interface (CI) which is
enabled by a new "x-vof" pseries machine option (stands for "Virtual Open
Firmware). When enabled, QEMU implements the custom H_OF_CLIENT hcall
which implements Open Firmware Client Interface (OF CI). This allows
using a smaller stateless firmware which does not have to manage
the device tree.

The new "vof.bin" firmware image is included with source code under
pc-bios/. It also includes RTAS blob.

This implements a handful of CI methods just to get -kernel/-initrd
working. In particular, this implements the device tree fetching and
simple memory allocator - "claim" (an OF CI memory allocator) and updates
"/memory@0/available" to report the client about available memory.

This implements changing some device tree properties which we know how
to deal with, the rest is ignored. To allow changes, this skips
fdt_pack() when x-vof=on as not packing the blob leaves some room for
appending.

In absence of SLOF, this assigns phandles to device tree nodes to make
device tree traversing work.

When x-vof=on, this adds "/chosen" every time QEMU (re)builds a tree.

This adds basic instances support which are managed by a hash map
ihandle -> [phandle].

Before the guest started, the used memory is:
0..e60 - the initial firmware
8000..10000 - stack
400000.. - kernel
3ea0000.. - initramdisk

This OF CI does not implement "interpret".

Unlike SLOF, this does not format uninitialized nvram. Instead, this
includes a disk image with pre-formatted nvram.

With this basic support, this can only boot into kernel directly.
However this is just enough for the petitboot kernel and initradmdisk to
boot from any possible source. Note this requires reasonably recent guest
kernel with:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=df5be5be8735

The immediate benefit is much faster booting time which especially
crucial with fully emulated early CPU bring up environments. Also this
may come handy when/if GRUB-in-the-userspace sees light of the day.

This separates VOF and sPAPR in a hope that VOF bits may be reused by
other POWERPC boards which do not support pSeries.

This is coded in assumption that later on we might be adding support for
booting from QEMU backends (blockdev is the first candidate) without
devices/drivers in between as OF1275 does not require that and
it is quite easy to so.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---

The example command line is:

/home/aik/pbuild/qemu-killslof-localhost-ppc64/qemu-system-ppc64 \
-nodefaults \
-chardev stdio,id=STDIO0,signal=off,mux=on \
-device spapr-vty,id=svty0,reg=0x71000110,chardev=STDIO0 \
-mon id=MON0,chardev=STDIO0,mode=readline \
-nographic \
-vga none \
-enable-kvm \
-m 2G \
-machine pseries,x-vof=on,cap-cfpc=broken,cap-sbbc=broken,cap-ibs=broken,cap-ccf-assist=off \
-kernel pbuild/kernel-le-guest/vmlinux \
-initrd pb/rootfs.cpio.xz \
-drive id=DRIVE0,if=none,file=./p/qemu-killslof/pc-bios/vof-nvram.bin,format=raw \
-global spapr-nvram.drive=DRIVE0 \
-snapshot \
-smp 8,threads=8 \
-L /home/aik/t/qemu-ppc64-bios/ \
-trace events=qemu_trace_events \
-d guest_errors \
-chardev socket,id=SOCKET0,server,nowait,path=qemu.mon.tmux26 \
-mon chardev=SOCKET0,mode=control

---
Changes:
v16:
* rebased on dwg/ppc-for-6.1
* s/SpaprVofInterface/VofMachineInterface/

v15:
* bugfix: claimed memory for the VOF itself
* ditched OF_STACK_ADDR and allocate one instead, now it starts from 0x8000
because it is aligned to its size (no particular reason though)
* coding style
* moved nvram.bin up one level
* ditched bool in the firmware
* made debugging code conditional using trace_event_get_state() + qemu_loglevel_mask()
* renamed the CAS interface to SpaprVofInterface
* added "write" which for now dumps the message and ihandle via
trace point for early debug assistance
* commented on when we allocate of_instances in vof_build_dt()
* store fw_size is SpaprMachine to let spapr_vof_reset() claim it
* many small fixes from v14's review

v14:
* check for truncates in readstr()
* ditched a separate vof_reset()
* spapr->vof is a pointer now, dropped the "on" field
* removed rtas_base from vof and updated comment why we allow setting it
* added myself to maintainers
* updated commit log about blockdev and other possible platforms
* added a note why new hcall is 0x5
* no in place endianness convertion in spapr_h_vof_client
* converted all cpu_physical_memory_read/write to address_space_rw
* git mv hw/ppc/spapr_vof_client.c hw/ppc/spapr_vof.c

v13:
* rebase on latest ppc-for-6.0
* shuffled code around to touch spapr.c less

v12:
* split VOF and SPAPR

v11:
* added g_autofree
* fixed gcc warnings
* fixed few leaks
* added nvram image to make "nvram --print-config" not crash;
Note that contrary to  MIN_NVRAM_SIZE (8 * KiB), the actual minimum size
is 16K, or it just does not work (empty output from "nvram")

v10:
* now rebased to compile with meson

v9:
* remove special handling of /rtas/rtas-size as now we always add it in QEMU
* removed leftovers from scsi/grub/stdout/stdin/...

v8:
* no read/write/seek
* no @dev in instances
* the machine flag is "x-vof" for now

v7:
* now we have a small firmware which loads at 0 as SLOF and starts from
0x100 as SLOF
* no MBR/ELF/GRUB business in QEMU anymore
* blockdev is a separate patch
* networking is a separate patch

v6:
* borrowed a big chunk of commit log introduction from David
* fixed initial stack pointer (points to the highest address of stack)
* traces for "interpret" and others
* disabled  translate_kernel_address() hack so grub can load (work in
progress)
* added "milliseconds" for grub
* fixed "claim" allocator again
* moved FDT_MAX_SIZE to spapr.h as spapr_of_client.c wants it too for CAS
* moved the most code possible from spapr.c to spapr_of_client.c, such as
RTAS, prom entry and FDT build/finalize
* separated blobs
* GRUB now proceeds to its console prompt (there are still other issues)
* parse MBR/GPT to find PReP and load GRUB

v5:
* made instances keep device and chardev pointers
* removed VIO dependencies
* print error if RTAS memory is not claimed as it should have been
* pack FDT as "quiesce"

v4:
* fixed open
* validate ihandles in "call-method"

v3:
* fixed phandles allocation
* s/__be32/uint32_t/ as we do not normally have __be32 type in qemu
* fixed size of /chosen/stdout
* bunch of renames
* do not create rtas properties at all, let the client deal with it;
instead setprop allows changing these in the FDT
* no more packing FDT when bios=off - nobody needs it and getprop does not
work otherwise
* allow updating initramdisk device tree properties (for zImage)
* added instances
* fixed stdout on OF's "write"
* removed special handling for stdout in OF client, spapr-vty handles it
instead

v2:
* fixed claim()
* added "setprop"
* cleaner client interface and RTAS blobs management
* boots to petitboot and further to the target system
* more trace points
---
 pc-bios/vof/Makefile   |  18 +
 hw/ppc/vof.h           |  37 ++
 include/hw/ppc/spapr.h |  17 +-
 pc-bios/vof/vof.h      |  38 ++
 hw/ppc/spapr.c         |  83 +++-
 hw/ppc/spapr_hcall.c   |  26 +-
 hw/ppc/spapr_vof.c     | 148 +++++++
 hw/ppc/vof.c           | 982 +++++++++++++++++++++++++++++++++++++++++
 pc-bios/vof/bootmem.c  |  14 +
 pc-bios/vof/ci.c       |  91 ++++
 pc-bios/vof/libc.c     |  92 ++++
 pc-bios/vof/main.c     |  21 +
 MAINTAINERS            |  11 +
 hw/ppc/meson.build     |   2 +
 hw/ppc/trace-events    |  24 +
 pc-bios/README         |   2 +
 pc-bios/vof-nvram.bin  | Bin 0 -> 16384 bytes
 pc-bios/vof.bin        | Bin 0 -> 3128 bytes
 pc-bios/vof/entry.S    |  51 +++
 pc-bios/vof/l.lds      |  48 ++
 20 files changed, 1693 insertions(+), 12 deletions(-)
 create mode 100644 pc-bios/vof/Makefile
 create mode 100644 hw/ppc/vof.h
 create mode 100644 pc-bios/vof/vof.h
 create mode 100644 hw/ppc/spapr_vof.c
 create mode 100644 hw/ppc/vof.c
 create mode 100644 pc-bios/vof/bootmem.c
 create mode 100644 pc-bios/vof/ci.c
 create mode 100644 pc-bios/vof/libc.c
 create mode 100644 pc-bios/vof/main.c
 create mode 100644 pc-bios/vof-nvram.bin
 create mode 100755 pc-bios/vof.bin
 create mode 100644 pc-bios/vof/entry.S
 create mode 100644 pc-bios/vof/l.lds

diff --git a/pc-bios/vof/Makefile b/pc-bios/vof/Makefile
new file mode 100644
index 000000000000..1451e0551818
--- /dev/null
+++ b/pc-bios/vof/Makefile
@@ -0,0 +1,18 @@
+all: build-all
+
+build-all: vof.bin
+
+%.o: %.S
+	cc -m32 -mbig-endian -c -o $@ $<
+
+%.o: %.c
+	cc -m32 -mbig-endian -c -fno-stack-protector -o $@ $<
+
+vof.elf: entry.o main.o ci.o bootmem.o libc.o
+	ld -nostdlib -e_start -Tl.lds -EB -o $@ $^
+
+%.bin: %.elf
+	objcopy -O binary -j .text -j .data -j .toc -j .got2 $^ $@
+
+clean:
+	rm -f *.o vof.bin vof.elf *~
diff --git a/hw/ppc/vof.h b/hw/ppc/vof.h
new file mode 100644
index 000000000000..fc397e4e0c9b
--- /dev/null
+++ b/hw/ppc/vof.h
@@ -0,0 +1,37 @@
+ /* Virtual Open Firmware */
+#ifndef HW_VOF_H
+#define HW_VOF_H
+
+typedef struct Vof {
+    uint32_t top_addr; /* copied from rma_size */
+    GArray *claimed; /* array of SpaprOfClaimed */
+    uint64_t claimed_base;
+    GHashTable *of_instances; /* ihandle -> SpaprOfInstance */
+    uint32_t of_instance_last;
+    char *bootargs;
+    uint32_t initrd_base; /* Updated in spapr at CAS */
+    long initrd_size; /* Updated in spapr at CAS */
+} Vof;
+
+uint32_t vof_client_call(void *fdt, Vof *vof, const char *service,
+                         uint32_t *args, unsigned nargs,
+                         uint32_t *rets, unsigned nrets);
+uint64_t vof_claim(void *fdt, Vof *vof, uint64_t virt, uint64_t size,
+                   uint64_t align);
+void vof_cleanup(Vof *vof);
+void vof_build_dt(void *fdt, Vof *vof, uint32_t top_addr);
+uint32_t vof_client_open_store(void *fdt, Vof *vof, const char *nodename,
+                               const char *prop, const char *path);
+
+#define TYPE_VOF_MACHINE "vof-machine"
+
+typedef struct VofMachineClass VofMachineClass;
+DECLARE_CLASS_CHECKERS(VofMachineClass, VOF_MACHINE, TYPE_VOF_MACHINE)
+
+struct VofMachineClass {
+    InterfaceClass parent;
+    target_ulong (*client_architecture_support)(CPUState *cs, target_ulong vec);
+    void (*quiesce)(void);
+};
+
+#endif /* HW_VOF_H */
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index bf7cab7a2ce1..3cb121dae707 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -12,6 +12,7 @@
 #include "hw/ppc/spapr_xive.h"  /* For SpaprXive */
 #include "hw/ppc/xics.h"        /* For ICSState */
 #include "hw/ppc/spapr_tpm_proxy.h"
+#include "hw/ppc/vof.h"
 
 struct SpaprVioBus;
 struct SpaprPhbState;
@@ -180,6 +181,8 @@ struct SpaprMachineState {
     uint64_t kernel_addr;
     uint32_t initrd_base;
     long initrd_size;
+    long fw_size;
+    Vof *vof;
     uint64_t rtc_offset; /* Now used only during incoming migration */
     struct PPCTimebase tb;
     bool has_graphics;
@@ -554,7 +557,9 @@ struct SpaprMachineState {
 /* Client Architecture support */
 #define KVMPPC_H_CAS            (KVMPPC_HCALL_BASE + 0x2)
 #define KVMPPC_H_UPDATE_DT      (KVMPPC_HCALL_BASE + 0x3)
-#define KVMPPC_HCALL_MAX        KVMPPC_H_UPDATE_DT
+/* 0x4 was used for KVMPPC_H_UPDATE_PHANDLE in SLOF */
+#define KVMPPC_H_VOF_CLIENT     (KVMPPC_HCALL_BASE + 0x5)
+#define KVMPPC_HCALL_MAX        KVMPPC_H_VOF_CLIENT
 
 /*
  * The hcall range 0xEF00 to 0xEF80 is reserved for use in facilitating
@@ -945,4 +950,14 @@ bool spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
 void spapr_set_all_lpcrs(target_ulong value, target_ulong mask);
 hwaddr spapr_get_rtas_addr(void);
 bool spapr_memory_hot_unplug_supported(SpaprMachineState *spapr);
+
+void spapr_vof_reset(SpaprMachineState *spapr, void *fdt,
+                     target_ulong *stack_ptr, Error **errp);
+void spapr_vof_quiesce(void);
+target_ulong spapr_h_vof_client(PowerPCCPU *cpu, SpaprMachineState *spapr,
+                                target_ulong opcode, target_ulong *args);
+target_ulong spapr_vof_client_architecture_support(CPUState *cs,
+                                                   target_ulong ovec_addr);
+void spapr_vof_client_dt_finalize(SpaprMachineState *spapr, void *fdt);
+
 #endif /* HW_SPAPR_H */
diff --git a/pc-bios/vof/vof.h b/pc-bios/vof/vof.h
new file mode 100644
index 000000000000..29c80374d6dd
--- /dev/null
+++ b/pc-bios/vof/vof.h
@@ -0,0 +1,38 @@
+#include <stdarg.h>
+
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+typedef unsigned long uint32_t;
+typedef unsigned long long uint64_t;
+#define NULL (0)
+#define PROM_ERROR (-1u)
+typedef unsigned long ihandle;
+typedef unsigned long phandle;
+typedef int size_t;
+typedef void client(void);
+
+/* globals */
+extern void _prom_entry(void); /* OF CI entry point (i.e. this firmware) */
+
+void do_boot(unsigned long addr, unsigned long r3, unsigned long r4);
+
+/* libc */
+int strlen(const char *s);
+int strcmp(const char *s1, const char *s2);
+void *memcpy(void *dest, const void *src, size_t n);
+int memcmp(const void *ptr1, const void *ptr2, size_t n);
+void *memmove(void *dest, const void *src, size_t n);
+void *memset(void *dest, int c, size_t size);
+
+/* CI wrappers */
+void ci_panic(const char *str);
+phandle ci_finddevice(const char *path);
+uint32_t ci_getprop(phandle ph, const char *propname, void *prop, int len);
+
+/* booting from -kernel */
+void boot_from_memory(uint64_t initrd, uint64_t initrdsize);
+
+/* Entry points for CI and RTAS */
+extern uint32_t ci_entry(uint32_t params);
+extern unsigned long hv_rtas(unsigned long params);
+extern unsigned int hv_rtas_size;
diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index 73a06df3b1b1..0a41fd893c47 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -103,6 +103,7 @@
 #define RTAS_MAX_ADDR           0x80000000 /* RTAS must stay below that */
 #define FW_MAX_SIZE             0x400000
 #define FW_FILE_NAME            "slof.bin"
+#define FW_FILE_NAME_VOF        "vof.bin"
 #define FW_OVERHEAD             0x2800000
 #define KERNEL_LOAD_ADDR        FW_MAX_SIZE
 
@@ -1625,22 +1626,41 @@ static void spapr_machine_reset(MachineState *machine)
 
     fdt = spapr_build_fdt(spapr, true, FDT_MAX_SIZE);
 
-    rc = fdt_pack(fdt);
+    if (spapr->vof) {
+        target_ulong stack_ptr = 0;
 
-    /* Should only fail if we've built a corrupted tree */
-    assert(rc == 0);
+        /*
+         * Claims initramdisk and stack which changes "available" so
+         * doing it befofe packing.
+         */
+        spapr_vof_reset(spapr, fdt, &stack_ptr, &error_fatal);
 
-    /* Load the fdt */
+        spapr_cpu_set_entry_state(first_ppc_cpu, SPAPR_ENTRY_POINT,
+                                  stack_ptr, spapr->initrd_base,
+                                  spapr->initrd_size);
+        /* We do not pack the FDT as the client may change properties. */
+    } else {
+        rc = fdt_pack(fdt);
+        /* Should only fail if we've built a corrupted tree */
+        assert(rc == 0);
+
+        spapr_cpu_set_entry_state(first_ppc_cpu, SPAPR_ENTRY_POINT,
+                                  0, fdt_addr, 0);
+    }
     qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
-    cpu_physical_memory_write(fdt_addr, fdt, fdt_totalsize(fdt));
+
     g_free(spapr->fdt_blob);
     spapr->fdt_size = fdt_totalsize(fdt);
     spapr->fdt_initial_size = spapr->fdt_size;
     spapr->fdt_blob = fdt;
 
     /* Set up the entry state */
-    spapr_cpu_set_entry_state(first_ppc_cpu, SPAPR_ENTRY_POINT, 0, fdt_addr, 0);
     first_ppc_cpu->env.gpr[5] = 0;
+    /* VOF client does not expect the FDT so we do not load it to the VM. */
+    if (!spapr->vof) {
+        /* Load the fdt */
+        cpu_physical_memory_write(fdt_addr, spapr->fdt_blob, spapr->fdt_size);
+    }
 
     spapr->fwnmi_system_reset_addr = -1;
     spapr->fwnmi_machine_check_addr = -1;
@@ -2640,13 +2660,14 @@ static void spapr_machine_init(MachineState *machine)
     SpaprMachineState *spapr = SPAPR_MACHINE(machine);
     SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
     MachineClass *mc = MACHINE_GET_CLASS(machine);
-    const char *bios_name = machine->firmware ?: FW_FILE_NAME;
+    const char *bios_default = !!spapr->vof ? FW_FILE_NAME_VOF : FW_FILE_NAME;
+    const char *bios_name = machine->firmware ?: bios_default;
     const char *kernel_filename = machine->kernel_filename;
     const char *initrd_filename = machine->initrd_filename;
     PCIHostState *phb;
     int i;
     MemoryRegion *sysmem = get_system_memory();
-    long load_limit, fw_size;
+    long load_limit;
     char *filename;
     Error *resize_hpt_err = NULL;
 
@@ -2963,8 +2984,8 @@ static void spapr_machine_init(MachineState *machine)
         error_report("Could not find LPAR firmware '%s'", bios_name);
         exit(1);
     }
-    fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
-    if (fw_size <= 0) {
+    spapr->fw_size = load_image_targphys(filename, 0, FW_MAX_SIZE);
+    if (spapr->fw_size <= 0) {
         error_report("Could not load LPAR firmware '%s'", filename);
         exit(1);
     }
@@ -2997,6 +3018,10 @@ static void spapr_machine_init(MachineState *machine)
     }
 
     qemu_cond_init(&spapr->fwnmi_machine_check_interlock_cond);
+
+    if (spapr->vof) {
+        spapr_register_hypercall(KVMPPC_H_VOF_CLIENT, spapr_h_vof_client);
+    }
 }
 
 #define DEFAULT_KVM_TYPE "auto"
@@ -3187,6 +3212,28 @@ static void spapr_set_resize_hpt(Object *obj, const char *value, Error **errp)
     }
 }
 
+static bool spapr_get_vof(Object *obj, Error **errp)
+{
+    SpaprMachineState *spapr = SPAPR_MACHINE(obj);
+
+    return spapr->vof != NULL;
+}
+
+static void spapr_set_vof(Object *obj, bool value, Error **errp)
+{
+    SpaprMachineState *spapr = SPAPR_MACHINE(obj);
+
+    if (spapr->vof) {
+        vof_cleanup(spapr->vof);
+        g_free(spapr->vof);
+        spapr->vof = NULL;
+    }
+    if (!value) {
+        return;
+    }
+    spapr->vof = g_malloc0(sizeof(*spapr->vof));
+}
+
 static char *spapr_get_ic_mode(Object *obj, Error **errp)
 {
     SpaprMachineState *spapr = SPAPR_MACHINE(obj);
@@ -3312,6 +3359,10 @@ static void spapr_instance_init(Object *obj)
                                     stringify(KERNEL_LOAD_ADDR)
                                     " for -kernel is the default");
     spapr->kernel_addr = KERNEL_LOAD_ADDR;
+    object_property_add_bool(obj, "x-vof", spapr_get_vof, spapr_set_vof);
+    object_property_set_description(obj, "x-vof",
+                                    "Enable Virtual Open Firmware");
+
     /* The machine class defines the default interrupt controller mode */
     spapr->irq = smc->irq;
     object_property_add_str(obj, "ic-mode", spapr_get_ic_mode,
@@ -4470,6 +4521,7 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     XICSFabricClass *xic = XICS_FABRIC_CLASS(oc);
     InterruptStatsProviderClass *ispc = INTERRUPT_STATS_PROVIDER_CLASS(oc);
     XiveFabricClass *xfc = XIVE_FABRIC_CLASS(oc);
+    VofMachineClass *vmc = VOF_MACHINE_CLASS(oc);
 
     mc->desc = "pSeries Logical Partition (PAPR compliant)";
     mc->ignore_boot_device_suffixes = true;
@@ -4549,6 +4601,9 @@ static void spapr_machine_class_init(ObjectClass *oc, void *data)
     smc->smp_threads_vsmt = true;
     smc->nr_xirqs = SPAPR_NR_XIRQS;
     xfc->match_nvt = spapr_match_nvt;
+
+    vmc->client_architecture_support = spapr_vof_client_architecture_support;
+    vmc->quiesce = spapr_vof_quiesce;
 }
 
 static const TypeInfo spapr_machine_info = {
@@ -4568,6 +4623,7 @@ static const TypeInfo spapr_machine_info = {
         { TYPE_XICS_FABRIC },
         { TYPE_INTERRUPT_STATS_PROVIDER },
         { TYPE_XIVE_FABRIC },
+        { TYPE_VOF_MACHINE },
         { }
     },
 };
@@ -5036,9 +5092,16 @@ static void spapr_machine_2_1_class_options(MachineClass *mc)
 }
 DEFINE_SPAPR_MACHINE(2_1, "2.1", false);
 
+static const TypeInfo vof_machine_info = {
+    .name = TYPE_VOF_MACHINE,
+    .parent = TYPE_INTERFACE,
+    .class_size = sizeof(VofMachineClass),
+};
+
 static void spapr_machine_register_types(void)
 {
     type_register_static(&spapr_machine_info);
+    type_register_static(&vof_machine_info);
 }
 
 type_init(spapr_machine_register_types)
diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index 7b5cd3553c26..0cdf90af6afb 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1806,7 +1806,13 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
         spapr_setup_hpt(spapr);
     }
 
-    fdt = spapr_build_fdt(spapr, false, fdt_bufsize);
+    if (spapr->vof && spapr->vof->initrd_base && spapr->vof->initrd_size) {
+        /* Update initramdisk location so the right area gets reserved below */
+        spapr->initrd_base = spapr->vof->initrd_base;
+        spapr->initrd_size = spapr->vof->initrd_size;
+    }
+
+    fdt = spapr_build_fdt(spapr, spapr->vof != NULL, fdt_bufsize);
 
     g_free(spapr->fdt_blob);
     spapr->fdt_size = fdt_totalsize(fdt);
@@ -1850,6 +1856,24 @@ static target_ulong h_client_architecture_support(PowerPCCPU *cpu,
     return ret;
 }
 
+target_ulong spapr_vof_client_architecture_support(CPUState *cs,
+                                                  target_ulong ovec_addr)
+{
+    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+
+    target_ulong ret = do_client_architecture_support(POWERPC_CPU(cs), spapr,
+                                                      ovec_addr, FDT_MAX_SIZE);
+
+    /*
+     * This adds stdout and generates phandles for boottime and CAS FDTs.
+     * It is alright to update the FDT here as do_client_architecture_support()
+     * does not pack it.
+     */
+    spapr_vof_client_dt_finalize(spapr, spapr->fdt_blob);
+
+    return ret;
+}
+
 static target_ulong h_get_cpu_characteristics(PowerPCCPU *cpu,
                                               SpaprMachineState *spapr,
                                               target_ulong opcode,
diff --git a/hw/ppc/spapr_vof.c b/hw/ppc/spapr_vof.c
new file mode 100644
index 000000000000..8a58364490f4
--- /dev/null
+++ b/hw/ppc/spapr_vof.c
@@ -0,0 +1,148 @@
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include <sys/ioctl.h>
+#include "qapi/error.h"
+#include "hw/ppc/spapr.h"
+#include "hw/ppc/spapr_vio.h"
+#include "hw/ppc/fdt.h"
+#include "sysemu/sysemu.h"
+#include "qom/qom-qobject.h"
+#include "trace.h"
+
+/* Copied from SLOF, and 4K is definitely not enough for GRUB */
+#define OF_STACK_SIZE       0x8000
+
+/* Defined as Big Endian */
+struct prom_args {
+    uint32_t service;
+    uint32_t nargs;
+    uint32_t nret;
+    uint32_t args[10];
+} QEMU_PACKED;
+
+target_ulong spapr_h_vof_client(PowerPCCPU *cpu, SpaprMachineState *spapr,
+                                target_ulong opcode, target_ulong *_args)
+{
+    target_ulong args_real = ppc64_phys_to_real(_args[0]);
+    struct prom_args args_be;
+    uint32_t args[ARRAY_SIZE(args_be.args)];
+    uint32_t rets[ARRAY_SIZE(args_be.args)] = { 0 }, ret;
+    char service[64];
+    unsigned nargs, nret, i;
+
+    if (address_space_rw(&address_space_memory, args_real,
+                         MEMTXATTRS_UNSPECIFIED, &args_be, sizeof(args_be),
+                         false) != MEMTX_OK) {
+        return H_HARDWARE;
+    }
+    nargs = be32_to_cpu(args_be.nargs);
+    if (nargs >= ARRAY_SIZE(args_be.args)) {
+        return H_PARAMETER;
+    }
+
+    if (address_space_rw(&address_space_memory, be32_to_cpu(args_be.service),
+                         MEMTXATTRS_UNSPECIFIED, service, sizeof(service),
+                         false) != MEMTX_OK) {
+        return H_HARDWARE;
+    }
+    if (strnlen(service, sizeof(service)) == sizeof(service)) {
+        /* Too long service name */
+        return H_PARAMETER;
+    }
+
+    for (i = 0; i < nargs; ++i) {
+        args[i] = be32_to_cpu(args_be.args[i]);
+    }
+
+    nret = be32_to_cpu(args_be.nret);
+    ret = vof_client_call(spapr->fdt_blob, spapr->vof, service,
+                          args, nargs, rets, nret);
+    if (!nret) {
+        return H_SUCCESS;
+    }
+
+    args_be.args[nargs] = cpu_to_be32(ret);
+    for (i = 1; i < nret; ++i) {
+        args_be.args[nargs + i] = cpu_to_be32(rets[i - 1]);
+    }
+
+    if (address_space_rw(&address_space_memory,
+                         args_real + offsetof(struct prom_args, args[nargs]),
+                         MEMTXATTRS_UNSPECIFIED, args_be.args + nargs,
+                         sizeof(args_be.args[0]) * nret, true) != MEMTX_OK) {
+        return H_HARDWARE;
+    }
+
+    return H_SUCCESS;
+}
+
+void spapr_vof_client_dt_finalize(SpaprMachineState *spapr, void *fdt)
+{
+    char *stdout_path = spapr_vio_stdout_path(spapr->vio_bus);
+
+    vof_build_dt(fdt, spapr->vof, spapr->rma_size);
+
+    /*
+     * SLOF-less setup requires an open instance of stdout for early
+     * kernel printk. By now all phandles are settled so we can open
+     * the default serial console.
+     */
+    if (stdout_path) {
+        _FDT(vof_client_open_store(fdt, spapr->vof, "/chosen", "stdout",
+                                   stdout_path));
+    }
+}
+
+void spapr_vof_reset(SpaprMachineState *spapr, void *fdt,
+                     target_ulong *stack_ptr, Error **errp)
+{
+    Vof *vof = spapr->vof;
+
+    vof_cleanup(vof);
+
+    spapr_vof_client_dt_finalize(spapr, fdt);
+
+    if (vof_claim(spapr->fdt_blob, vof, 0, spapr->fw_size, 0) == -1) {
+        error_setg(errp, "Memory for firmware is in use");
+        return;
+    }
+
+    *stack_ptr = vof_claim(spapr->fdt_blob, vof, 0, OF_STACK_SIZE,
+                           OF_STACK_SIZE);
+    if (*stack_ptr == -1) {
+        error_setg(errp, "Memory allocation for stack failed");
+        return;
+    }
+    /*
+     * Stack grows downwards and we also reserve here space for
+     * the minimum stack frame.
+     */
+    *stack_ptr += OF_STACK_SIZE - 0x20;
+
+    if (spapr->kernel_size &&
+        vof_claim(spapr->fdt_blob, vof, spapr->kernel_addr, spapr->kernel_size,
+                  0) == -1) {
+        error_setg(errp, "Memory for kernel is in use");
+        return;
+    }
+
+    if (spapr->initrd_size &&
+        vof_claim(spapr->fdt_blob, vof, spapr->initrd_base, spapr->initrd_size,
+                  0) == -1) {
+        error_setg(errp, "Memory for initramdisk is in use");
+        return;
+    }
+
+    /*
+     * We skip writing FDT as nothing expects it; OF client interface is
+     * going to be used for reading the device tree.
+     */
+}
+
+void spapr_vof_quiesce(void)
+{
+    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
+
+    spapr->fdt_size = fdt_totalsize(spapr->fdt_blob);
+    spapr->fdt_initial_size = spapr->fdt_size;
+}
diff --git a/hw/ppc/vof.c b/hw/ppc/vof.c
new file mode 100644
index 000000000000..86e4c20b67e7
--- /dev/null
+++ b/hw/ppc/vof.c
@@ -0,0 +1,982 @@
+/*
+ * QEMU PowerPC Virtual Open Firmware.
+ *
+ * This implements client interface from OpenFirmware IEEE1275 on the QEMU
+ * side to leave only a very basic firmware in the VM.
+ *
+ * Copyright (c) 2020 IBM Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qapi/error.h"
+#include <sys/ioctl.h>
+#include "exec/ram_addr.h"
+#include "exec/address-spaces.h"
+#include "qemu/timer.h"
+#include "qemu/range.h"
+#include "hw/ppc/vof.h"
+#include "hw/ppc/fdt.h"
+#include "sysemu/runstate.h"
+#include "qom/qom-qobject.h"
+#include "trace.h"
+
+#include <libfdt.h>
+
+/*
+ * OF 1275 "nextprop" description suggests is it 32 bytes max but
+ * LoPAPR defines "ibm,query-interrupt-source-number" which is 33 chars long.
+ */
+#define OF_PROPNAME_LEN_MAX 64
+
+#define VOF_MAX_PATH        256
+#define VOF_MAX_PROPLEN     2048
+#define VOF_MAX_METHODLEN   256
+#define VOF_MAX_FORTHCODE   256
+#define VOF_VTY_BUF_SIZE    256
+
+typedef struct {
+    uint64_t start;
+    uint64_t size;
+} OfClaimed;
+
+typedef struct {
+    char *path; /* the path used to open the instance */
+    uint32_t phandle;
+} OfInstance;
+
+#define VOF_MEM_READ(pa, buf, size) \
+    address_space_read_full(&address_space_memory, \
+    (pa), MEMTXATTRS_UNSPECIFIED, (buf), (size))
+#define VOF_MEM_WRITE(pa, buf, size) \
+    address_space_write(&address_space_memory, \
+    (pa), MEMTXATTRS_UNSPECIFIED, (buf), (size))
+
+static int readstr(hwaddr pa, char *buf, int size)
+{
+    if (VOF_MEM_READ(pa, buf, size) != MEMTX_OK) {
+        return -1;
+    }
+    if (strnlen(buf, size) == size) {
+        buf[size - 1] = '\0';
+        trace_vof_error_str_truncated(buf, size);
+        return -1;
+    }
+    return 0;
+}
+
+static bool cmpservice(const char *s, unsigned nargs, unsigned nret,
+                       const char *s1, unsigned nargscheck, unsigned nretcheck)
+{
+    if (strcmp(s, s1)) {
+        return false;
+    }
+    if ((nargscheck && (nargs != nargscheck)) ||
+        (nretcheck && (nret != nretcheck))) {
+        trace_vof_error_param(s, nargscheck, nretcheck, nargs, nret);
+        return false;
+    }
+
+    return true;
+}
+
+static void prop_format(char *tval, int tlen, const void *prop, int len)
+{
+    int i;
+    const unsigned char *c;
+    char *t;
+    const char bin[] = "...";
+
+    for (i = 0, c = prop; i < len; ++i, ++c) {
+        if (*c == '\0' && i == len - 1) {
+            strncpy(tval, prop, tlen - 1);
+            return;
+        }
+        if (*c < 0x20 || *c >= 0x80) {
+            break;
+        }
+    }
+
+    for (i = 0, c = prop, t = tval; i < len; ++i, ++c) {
+        if (t >= tval + tlen - sizeof(bin) - 1 - 2 - 1) {
+            strcpy(t, bin);
+            return;
+        }
+        if (i && i % 4 == 0 && i != len - 1) {
+            strcat(t, " ");
+            ++t;
+        }
+        t += sprintf(t, "%02X", *c & 0xFF);
+    }
+}
+
+static int get_path(const void *fdt, int offset, char *buf, int len)
+{
+    int ret;
+
+    ret = fdt_get_path(fdt, offset, buf, len - 1);
+    if (ret < 0) {
+        return ret;
+    }
+
+    buf[len - 1] = 0;
+
+    return strlen(buf) + 1;
+}
+
+static int phandle_to_path(const void *fdt, uint32_t ph, char *buf, int len)
+{
+    int ret;
+
+    ret = fdt_node_offset_by_phandle(fdt, ph);
+    if (ret < 0) {
+        return ret;
+    }
+
+    return get_path(fdt, ret, buf, len);
+}
+
+static uint32_t vof_finddevice(const void *fdt, uint32_t nodeaddr)
+{
+    char fullnode[1024];
+    uint32_t ret = -1;
+    int offset;
+
+    if (readstr(nodeaddr, fullnode, sizeof(fullnode))) {
+        return (uint32_t) ret;
+    }
+
+    offset = fdt_path_offset(fdt, fullnode);
+    if (offset >= 0) {
+        ret = fdt_get_phandle(fdt, offset);
+    }
+    trace_vof_finddevice(fullnode, ret);
+    return (uint32_t) ret;
+}
+
+static uint32_t vof_getprop(const void *fdt, uint32_t nodeph, uint32_t pname,
+                            uint32_t valaddr, uint32_t vallen)
+{
+    char propname[OF_PROPNAME_LEN_MAX + 1];
+    uint32_t ret = 0;
+    int proplen = 0;
+    const void *prop;
+    char trval[64] = "";
+    int nodeoff = fdt_node_offset_by_phandle(fdt, nodeph);
+    bool write0 = false;
+
+    if (readstr(pname, propname, sizeof(propname))) {
+        return -1;
+    }
+    if (strcmp(propname, "name") == 0) {
+        prop = fdt_get_name(fdt, nodeoff, &proplen);
+        if (prop) {
+            const void *unit = memchr(prop, '@', proplen);
+
+            if (unit) {
+                proplen = unit - prop;
+                write0 = true;
+            }
+        }
+        proplen += 1;
+    } else {
+        prop = fdt_getprop(fdt, nodeoff, propname, &proplen);
+    }
+
+    if (prop) {
+        int cb = MIN(proplen, vallen);
+        const char zero = 0;
+
+        if (VOF_MEM_WRITE(valaddr, prop, cb) != MEMTX_OK ||
+            /* if that was "name" with a unit address, overwrite '@' with '0' */
+            (write0 &&
+             cb == proplen &&
+             VOF_MEM_WRITE(valaddr + cb - 1, &zero, 1) != MEMTX_OK)) {
+            ret = -1;
+        } else {
+            /*
+             * OF1275 says:
+             * "Size is either the actual size of the property, or -1 if name
+             * does not exist", hence returning proplen instead of cb.
+             */
+            ret = proplen;
+            /* Do not format a value if tracepoint is silent, for performance */
+            if (trace_event_get_state(TRACE_VOF_GETPROP) &&
+                qemu_loglevel_mask(LOG_TRACE)) {
+                prop_format(trval, sizeof(trval), prop, ret);
+            }
+        }
+    } else {
+        ret = -1;
+    }
+    trace_vof_getprop(nodeph, propname, ret, trval);
+
+    return ret;
+}
+
+static uint32_t vof_getproplen(const void *fdt, uint32_t nodeph, uint32_t pname)
+{
+    char propname[OF_PROPNAME_LEN_MAX + 1];
+    uint32_t ret = 0;
+    int proplen = 0;
+    const void *prop;
+    int nodeoff = fdt_node_offset_by_phandle(fdt, nodeph);
+
+    if (readstr(pname, propname, sizeof(propname))) {
+        return -1;
+    }
+    if (strcmp(propname, "name") == 0) {
+        prop = fdt_get_name(fdt, nodeoff, &proplen);
+        if (prop) {
+            const void *unit = memchr(prop, '@', proplen);
+
+            if (unit) {
+                proplen = unit - prop;
+            }
+        }
+        proplen += 1;
+    } else {
+        prop = fdt_getprop(fdt, nodeoff, propname, &proplen);
+    }
+
+    if (prop) {
+        ret = proplen;
+    } else {
+        ret = -1;
+    }
+    trace_vof_getproplen(nodeph, propname, ret);
+
+    return ret;
+}
+
+static uint32_t vof_setprop(void *fdt, Vof *vof,
+                            uint32_t nodeph, uint32_t pname,
+                            uint32_t valaddr, uint32_t vallen)
+{
+    char propname[OF_PROPNAME_LEN_MAX + 1];
+    uint32_t ret = -1;
+    int offset;
+    char trval[64] = "";
+    char nodepath[VOF_MAX_PATH] = "";
+    g_autofree char *data = NULL;
+
+    if (vallen > VOF_MAX_PROPLEN) {
+        goto trace_exit;
+    }
+    if (readstr(pname, propname, sizeof(propname))) {
+        goto trace_exit;
+    }
+    offset = fdt_node_offset_by_phandle(fdt, nodeph);
+    if (offset < 0) {
+        goto trace_exit;
+    }
+    ret = get_path(fdt, offset, nodepath, sizeof(nodepath));
+    if (ret <= 0) {
+        goto trace_exit;
+    }
+
+    ret = -1;
+    /*
+     * We only allow changing properties which we know how to update in QEMU
+     * OR
+     * the ones which we know that they need to survive during "quiesce".
+     */
+    if (strcmp(nodepath, "/rtas") == 0) {
+        if (strcmp(propname, "linux,rtas-base") == 0 ||
+             strcmp(propname, "linux,rtas-entry") == 0) {
+            /* These need to survive quiesce so let them store in the FDT */
+        } else {
+            goto trace_exit;
+        }
+    } else if (strcmp(nodepath, "/chosen") == 0) {
+        if (strcmp(propname, "bootargs") == 0) {
+            char val[1024];
+
+            if (readstr(valaddr, val, sizeof(val))) {
+                goto trace_exit;
+            }
+            g_free(vof->bootargs);
+            vof->bootargs = g_strdup(val);
+            vallen = strlen(vof->bootargs) + 1;
+        } else  if (strcmp(propname, "linux,initrd-start") == 0) {
+            if (vallen == sizeof(uint32_t)) {
+                vof->initrd_base = ldl_be_phys(first_cpu->as, valaddr);
+            } else if (vallen == sizeof(uint64_t)) {
+                vof->initrd_base = ldq_be_phys(first_cpu->as, valaddr);
+            } else {
+                goto trace_exit;
+            }
+        } else if (strcmp(propname, "linux,initrd-end") == 0) {
+            if (vallen == sizeof(uint32_t)) {
+                vof->initrd_size = ldl_be_phys(first_cpu->as, valaddr) -
+                    vof->initrd_base;
+            } else if (vallen == sizeof(uint64_t)) {
+                vof->initrd_size = ldq_be_phys(first_cpu->as, valaddr) -
+                    vof->initrd_base;
+            } else {
+                goto trace_exit;
+            }
+        } else {
+            goto trace_exit;
+        }
+    } else {
+        goto trace_exit;
+    }
+
+    data = g_malloc0(vallen);
+    if ((VOF_MEM_READ(valaddr, data, vallen) == MEMTX_OK) &&
+        !fdt_setprop(fdt, offset, propname, data, vallen)) {
+        ret = vallen;
+        if (trace_event_get_state(TRACE_VOF_SETPROP) &&
+            qemu_loglevel_mask(LOG_TRACE)) {
+            prop_format(trval, sizeof(trval), data, ret);
+        }
+    }
+
+trace_exit:
+    trace_vof_setprop(nodeph, propname, trval, vallen, ret);
+
+    return ret;
+}
+
+static uint32_t vof_nextprop(const void *fdt, uint32_t phandle,
+                             uint32_t prevaddr, uint32_t nameaddr)
+{
+    int offset, nodeoff = fdt_node_offset_by_phandle(fdt, phandle);
+    char prev[OF_PROPNAME_LEN_MAX + 1];
+    const char *tmp;
+
+    if (readstr(prevaddr, prev, sizeof(prev))) {
+        return -1;
+    }
+
+    fdt_for_each_property_offset(offset, fdt, nodeoff) {
+        if (!fdt_getprop_by_offset(fdt, offset, &tmp, NULL)) {
+            return 0;
+        }
+        if (prev[0] == '\0' || strcmp(prev, tmp) == 0) {
+            if (prev[0] != '\0') {
+                offset = fdt_next_property_offset(fdt, offset);
+                if (offset < 0) {
+                    return 0;
+                }
+            }
+            if (!fdt_getprop_by_offset(fdt, offset, &tmp, NULL)) {
+                return 0;
+            }
+
+            if (VOF_MEM_WRITE(nameaddr, tmp, strlen(tmp) + 1) != MEMTX_OK) {
+                return -1;
+            }
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static uint32_t vof_peer(const void *fdt, uint32_t phandle)
+{
+    int ret;
+
+    if (phandle == 0) {
+        ret = fdt_path_offset(fdt, "/");
+    } else {
+        ret = fdt_next_subnode(fdt, fdt_node_offset_by_phandle(fdt, phandle));
+    }
+
+    if (ret < 0) {
+        ret = 0;
+    } else {
+        ret = fdt_get_phandle(fdt, ret);
+    }
+
+    return ret;
+}
+
+static uint32_t vof_child(const void *fdt, uint32_t phandle)
+{
+    int ret = fdt_first_subnode(fdt, fdt_node_offset_by_phandle(fdt, phandle));
+
+    if (ret < 0) {
+        ret = 0;
+    } else {
+        ret = fdt_get_phandle(fdt, ret);
+    }
+
+    return ret;
+}
+
+static uint32_t vof_parent(const void *fdt, uint32_t phandle)
+{
+    int ret = fdt_parent_offset(fdt, fdt_node_offset_by_phandle(fdt, phandle));
+
+    if (ret < 0) {
+        ret = 0;
+    } else {
+        ret = fdt_get_phandle(fdt, ret);
+    }
+
+    return ret;
+}
+
+static uint32_t vof_do_open(void *fdt, Vof *vof, const char *path)
+{
+    int offset;
+    uint32_t ret = 0;
+    OfInstance *inst = NULL;
+
+    if (vof->of_instance_last == 0xFFFFFFFF) {
+        /* We do not recycle ihandles yet */
+        goto trace_exit;
+    }
+
+    offset = fdt_path_offset(fdt, path);
+    if (offset < 0) {
+        trace_vof_error_unknown_path(path);
+        goto trace_exit;
+    }
+
+    inst = g_new0(OfInstance, 1);
+    inst->phandle = fdt_get_phandle(fdt, offset);
+    g_assert(inst->phandle);
+    ++vof->of_instance_last;
+
+    inst->path = g_strdup(path);
+    g_hash_table_insert(vof->of_instances,
+                        GINT_TO_POINTER(vof->of_instance_last),
+                        inst);
+    ret = vof->of_instance_last;
+
+trace_exit:
+    trace_vof_open(path, inst ? inst->phandle : 0, ret);
+
+    return ret;
+}
+
+uint32_t vof_client_open_store(void *fdt, Vof *vof, const char *nodename,
+                               const char *prop, const char *path)
+{
+    int node = fdt_path_offset(fdt, nodename);
+    uint32_t inst = vof_do_open(fdt, vof, path);
+
+    return fdt_setprop_cell(fdt, node, prop, inst);
+}
+
+static uint32_t vof_open(void *fdt, Vof *vof, uint32_t pathaddr)
+{
+    char path[VOF_MAX_PATH];
+
+    if (readstr(pathaddr, path, sizeof(path))) {
+        return -1;
+    }
+
+    return vof_do_open(fdt, vof, path);
+}
+
+static void vof_close(Vof *vof, uint32_t ihandle)
+{
+    if (!g_hash_table_remove(vof->of_instances, GINT_TO_POINTER(ihandle))) {
+        trace_vof_error_unknown_ihandle_close(ihandle);
+    }
+}
+
+static uint32_t vof_instance_to_package(Vof *vof, uint32_t ihandle)
+{
+    gpointer instp = g_hash_table_lookup(vof->of_instances,
+                                         GINT_TO_POINTER(ihandle));
+    uint32_t ret = -1;
+
+    if (instp) {
+        ret = ((OfInstance *)instp)->phandle;
+    }
+    trace_vof_instance_to_package(ihandle, ret);
+
+    return ret;
+}
+
+static uint32_t vof_package_to_path(const void *fdt, uint32_t phandle,
+                                    uint32_t buf, uint32_t len)
+{
+    uint32_t ret = -1;
+    char tmp[VOF_MAX_PATH] = "";
+
+    ret = phandle_to_path(fdt, phandle, tmp, sizeof(tmp));
+    if (ret > 0) {
+        if (VOF_MEM_WRITE(buf, tmp, ret) != MEMTX_OK) {
+            ret = -1;
+        }
+    }
+
+    trace_vof_package_to_path(phandle, tmp, ret);
+
+    return ret;
+}
+
+static uint32_t vof_instance_to_path(void *fdt, Vof *vof, uint32_t ihandle,
+                                     uint32_t buf, uint32_t len)
+{
+    uint32_t ret = -1;
+    uint32_t phandle = vof_instance_to_package(vof, ihandle);
+    char tmp[VOF_MAX_PATH] = "";
+
+    if (phandle != -1) {
+        ret = phandle_to_path(fdt, phandle, tmp, sizeof(tmp));
+        if (ret > 0) {
+            if (VOF_MEM_WRITE(buf, tmp, ret) != MEMTX_OK) {
+                ret = -1;
+            }
+        }
+    }
+    trace_vof_instance_to_path(ihandle, phandle, tmp, ret);
+
+    return ret;
+}
+
+static uint32_t vof_write(Vof *vof, uint32_t ihandle, uint32_t buf,
+                          uint32_t len)
+{
+    char tmp[VOF_VTY_BUF_SIZE];
+    int toread, toprint, cb = MIN(len, sizeof(tmp) - 1);
+    OfInstance *inst = (OfInstance *)
+        g_hash_table_lookup(vof->of_instances, GINT_TO_POINTER(ihandle));
+
+    if (!inst) {
+        trace_vof_error_write(ihandle);
+        return -1;
+    }
+    while (cb > 0) {
+        toread = MIN(cb, sizeof(tmp) - 1);
+
+        cpu_physical_memory_read(buf, tmp, toread);
+
+        toprint = toread;
+
+        if (trace_event_get_state(TRACE_VOF_WRITE) &&
+            qemu_loglevel_mask(LOG_TRACE)) {
+            char *c;
+
+            for (c = tmp; c < tmp + toprint; ++c) {
+                if (*c < 0x20 || *c >= 0x7f) {
+                    *c = '~';
+                }
+            }
+            tmp[toprint] = '\0';
+            trace_vof_write(ihandle, toprint, tmp);
+        }
+
+        buf += toprint;
+        cb -= toprint;
+    }
+
+    return len;
+}
+
+static void vof_claimed_dump(GArray *claimed)
+{
+    int i;
+    OfClaimed c;
+
+    if (trace_event_get_state(TRACE_VOF_CLAIMED) &&
+        qemu_loglevel_mask(LOG_TRACE)) {
+
+        for (i = 0; i < claimed->len; ++i) {
+            c = g_array_index(claimed, OfClaimed, i);
+            trace_vof_claimed(c.start, c.start + c.size, c.size);
+        }
+    }
+}
+
+static bool vof_claim_avail(GArray *claimed, uint64_t virt, uint64_t size)
+{
+    int i;
+    OfClaimed c;
+
+    for (i = 0; i < claimed->len; ++i) {
+        c = g_array_index(claimed, OfClaimed, i);
+        if (ranges_overlap(c.start, c.size, virt, size)) {
+            return false;
+        }
+    }
+
+    return true;
+}
+
+static void vof_claim_add(GArray *claimed, uint64_t virt, uint64_t size)
+{
+    OfClaimed newclaim;
+
+    newclaim.start = virt;
+    newclaim.size = size;
+    g_array_append_val(claimed, newclaim);
+}
+
+static gint of_claimed_compare_func(gconstpointer a, gconstpointer b)
+{
+    return ((OfClaimed *)a)->start - ((OfClaimed *)b)->start;
+}
+
+static void vof_dt_memory_available(void *fdt, GArray *claimed, uint64_t base)
+{
+    int i, n, offset, proplen = 0;
+    uint64_t *mem0_reg;
+    g_autofree struct { uint64_t start, size; } *avail = NULL;
+
+    if (!fdt || !claimed) {
+        return;
+    }
+
+    offset = fdt_path_offset(fdt, "/memory@0");
+    _FDT(offset);
+
+    mem0_reg = (uint64_t *) fdt_getprop(fdt, offset, "reg", &proplen);
+    if (!mem0_reg || proplen != 2 * sizeof(uint64_t)) {
+        return;
+    }
+
+    g_array_sort(claimed, of_claimed_compare_func);
+    vof_claimed_dump(claimed);
+
+    avail = g_malloc0(sizeof(avail[0]) * claimed->len);
+    for (i = 0, n = 0; i < claimed->len; ++i) {
+        OfClaimed c = g_array_index(claimed, OfClaimed, i);
+        uint64_t size;
+
+        if (i < claimed->len - 1) {
+            OfClaimed cn = g_array_index(claimed, OfClaimed, i + 1);
+
+            size = cn.start - avail[n].start;
+        } else {
+            size = be64_to_cpu(mem0_reg[1]) - avail[n].start;
+        }
+        avail[n].start = cpu_to_be64(c.start + c.size);
+        avail[n].size = cpu_to_be64(size);
+
+        if (size) {
+            trace_vof_avail(c.start + c.size, c.start + c.size + size, size);
+            ++n;
+        }
+    }
+    _FDT((fdt_setprop(fdt, offset, "available", avail, sizeof(avail[0]) * n)));
+}
+
+/*
+ * OF1275:
+ * "Allocates size bytes of memory. If align is zero, the allocated range
+ * begins at the virtual address virt. Otherwise, an aligned address is
+ * automatically chosen and the input argument virt is ignored".
+ *
+ * In other words, exactly one of @virt and @align is non-zero.
+ */
+uint64_t vof_claim(void *fdt, Vof *vof, uint64_t virt, uint64_t size,
+                   uint64_t align)
+{
+    uint64_t ret;
+
+    if (size == 0) {
+        ret = -1;
+    } else if (align == 0) {
+        if (!vof_claim_avail(vof->claimed, virt, size)) {
+            ret = -1;
+        } else {
+            ret = virt;
+        }
+    } else {
+        vof->claimed_base = QEMU_ALIGN_UP(vof->claimed_base, align);
+        while (1) {
+            if (vof->claimed_base >= vof->top_addr) {
+                error_report("Out of RMA memory for the OF client");
+                return -1;
+            }
+            if (vof_claim_avail(vof->claimed, vof->claimed_base, size)) {
+                break;
+            }
+            vof->claimed_base += size;
+        }
+        ret = vof->claimed_base;
+    }
+
+    if (ret != -1) {
+        vof->claimed_base = MAX(vof->claimed_base, ret + size);
+        vof_claim_add(vof->claimed, ret, size);
+        /* The client reads "/memory@0/available" to know where it can claim */
+        vof_dt_memory_available(fdt, vof->claimed, vof->claimed_base);
+    }
+    trace_vof_claim(virt, size, align, ret);
+
+    return ret;
+}
+
+static uint32_t vof_release(void *fdt, Vof *vof, uint64_t virt, uint64_t size)
+{
+    uint32_t ret = -1;
+    int i;
+    GArray *claimed = vof->claimed;
+    OfClaimed c;
+
+    for (i = 0; i < claimed->len; ++i) {
+        c = g_array_index(claimed, OfClaimed, i);
+        if (c.start == virt && c.size == size) {
+            g_array_remove_index(claimed, i);
+            vof_dt_memory_available(fdt, vof->claimed, vof->claimed_base);
+            ret = 0;
+            break;
+        }
+    }
+
+    trace_vof_release(virt, size, ret);
+
+    return ret;
+}
+
+static void vof_instantiate_rtas(Error **errp)
+{
+    error_setg(errp, "The firmware should have instantiated RTAS");
+}
+
+static uint32_t vof_call_method(Vof *vof, uint32_t methodaddr, uint32_t ihandle,
+                                uint32_t param1, uint32_t param2,
+                                uint32_t param3, uint32_t param4,
+                                uint32_t *ret2)
+{
+    uint32_t ret = -1;
+    char method[VOF_MAX_METHODLEN] = "";
+    OfInstance *inst;
+
+    if (!ihandle) {
+        goto trace_exit;
+    }
+
+    inst = (OfInstance *) g_hash_table_lookup(vof->of_instances,
+                                              GINT_TO_POINTER(ihandle));
+    if (!inst) {
+        goto trace_exit;
+    }
+
+    if (readstr(methodaddr, method, sizeof(method))) {
+        goto trace_exit;
+    }
+
+    if (strcmp(inst->path, "/") == 0) {
+        if (strcmp(method, "ibm,client-architecture-support") == 0) {
+            Object *vmo = object_dynamic_cast(qdev_get_machine(),
+                                              TYPE_VOF_MACHINE);
+
+            if (vmo) {
+                VofMachineClass *vmc = VOF_MACHINE_GET_CLASS(vmo);
+
+                ret = vmc->client_architecture_support(first_cpu, param1);
+            }
+
+            *ret2 = 0;
+        }
+    } else if (strcmp(inst->path, "/rtas") == 0) {
+        if (strcmp(method, "instantiate-rtas") == 0) {
+            vof_instantiate_rtas(&error_fatal);
+            ret = 0;
+            *ret2 = param1; /* rtas-base */
+        }
+    } else {
+        trace_vof_error_unknown_method(method);
+    }
+
+trace_exit:
+    trace_vof_method(ihandle, method, param1, ret, *ret2);
+
+    return ret;
+}
+
+static uint32_t vof_call_interpret(uint32_t cmdaddr, uint32_t param1,
+                                   uint32_t param2, uint32_t *ret2)
+{
+    uint32_t ret = -1;
+    char cmd[VOF_MAX_FORTHCODE] = "";
+
+    /* No interpret implemented */
+    readstr(cmdaddr, cmd, sizeof(cmd));
+    trace_vof_interpret(cmd, param1, param2, ret, *ret2);
+
+    return ret;
+}
+
+static void vof_quiesce(void *fdt, Vof *vof)
+{
+    Object *vmo = object_dynamic_cast(qdev_get_machine(), TYPE_VOF_MACHINE);
+    /*
+     * After "quiesce", no change should be made to the FDT and
+     * packing FDT ensures this.
+     */
+    int rc = fdt_pack(fdt);
+
+    assert(rc == 0);
+
+    if (vmo) {
+        VofMachineClass *vmc = VOF_MACHINE_GET_CLASS(vmo);
+
+        vmc->quiesce();
+    }
+
+    vof_claimed_dump(vof->claimed);
+}
+
+uint32_t vof_client_call(void *fdt, Vof *vof, const char *service,
+                         uint32_t *args, unsigned nargs,
+                         uint32_t *rets, unsigned nrets)
+{
+    uint32_t ret = 0;
+
+    /* @nrets includes the value which this function returns */
+#define cmpserv(s, a, r) \
+    cmpservice(service, nargs, nrets, (s), (a), (r))
+
+    if (cmpserv("finddevice", 1, 1)) {
+        ret = vof_finddevice(fdt, args[0]);
+    } else if (cmpserv("getprop", 4, 1)) {
+        ret = vof_getprop(fdt, args[0], args[1], args[2], args[3]);
+    } else if (cmpserv("getproplen", 2, 1)) {
+        ret = vof_getproplen(fdt, args[0], args[1]);
+    } else if (cmpserv("setprop", 4, 1)) {
+        ret = vof_setprop(fdt, vof, args[0], args[1], args[2], args[3]);
+    } else if (cmpserv("nextprop", 3, 1)) {
+        ret = vof_nextprop(fdt, args[0], args[1], args[2]);
+    } else if (cmpserv("peer", 1, 1)) {
+        ret = vof_peer(fdt, args[0]);
+    } else if (cmpserv("child", 1, 1)) {
+        ret = vof_child(fdt, args[0]);
+    } else if (cmpserv("parent", 1, 1)) {
+        ret = vof_parent(fdt, args[0]);
+    } else if (cmpserv("open", 1, 1)) {
+        ret = vof_open(fdt, vof, args[0]);
+    } else if (cmpserv("close", 1, 0)) {
+        vof_close(vof, args[0]);
+    } else if (cmpserv("instance-to-package", 1, 1)) {
+        ret = vof_instance_to_package(vof, args[0]);
+    } else if (cmpserv("package-to-path", 3, 1)) {
+        ret = vof_package_to_path(fdt, args[0], args[1], args[2]);
+    } else if (cmpserv("instance-to-path", 3, 1)) {
+        ret = vof_instance_to_path(fdt, vof, args[0], args[1], args[2]);
+    } else if (cmpserv("write", 3, 1)) {
+        ret = vof_write(vof, args[0], args[1], args[2]);
+    } else if (cmpserv("claim", 3, 1)) {
+        ret = vof_claim(fdt, vof, args[0], args[1], args[2]);
+    } else if (cmpserv("release", 2, 0)) {
+        ret = vof_release(fdt, vof, args[0], args[1]);
+    } else if (cmpserv("call-method", 0, 0)) {
+        ret = vof_call_method(vof, args[0], args[1], args[2], args[3], args[4],
+                              args[5], rets);
+    } else if (cmpserv("interpret", 0, 0)) {
+        ret = vof_call_interpret(args[0], args[1], args[2], rets);
+    } else if (cmpserv("milliseconds", 0, 1)) {
+        ret = qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL);
+    } else if (cmpserv("quiesce", 0, 0)) {
+        vof_quiesce(fdt, vof);
+    } else if (cmpserv("exit", 0, 0)) {
+        error_report("Stopped as the VM requested \"exit\"");
+        vm_stop(RUN_STATE_PAUSED); /* Or qemu_system_guest_panicked(NULL); ? */
+    } else {
+        trace_vof_error_unknown_service(service, nargs, nrets);
+        ret = -1;
+    }
+
+    return ret;
+}
+
+static void of_instance_free(gpointer data)
+{
+    OfInstance *inst = (OfInstance *) data;
+
+    g_free(inst->path);
+    g_free(inst);
+}
+
+void vof_cleanup(Vof *vof)
+{
+    if (vof->claimed) {
+        g_array_unref(vof->claimed);
+    }
+    if (vof->of_instances) {
+        g_hash_table_unref(vof->of_instances);
+    }
+    vof->claimed = NULL;
+    vof->of_instances = NULL;
+}
+
+void vof_build_dt(void *fdt, Vof *vof, uint32_t top_addr)
+{
+    uint32_t phandle;
+    int i, offset, proplen = 0;
+    const void *prop;
+    bool found = false;
+    GArray *phandles = g_array_new(false, false, sizeof(uint32_t));
+
+    /*
+     * Here is the first time we need of_instances and claimed. These are
+     * released on vof_cleanup() (called when reset) or when vof=off but
+     * they need to survive ibm,client-architecture-support so we do not
+     * always reset them here.
+     */
+    if (!vof->of_instances) {
+        vof->of_instances = g_hash_table_new_full(g_direct_hash, g_direct_equal,
+                                                  NULL, of_instance_free);
+    }
+    if (!vof->claimed) {
+        vof->claimed = g_array_new(false, false, sizeof(OfClaimed));
+    }
+
+    vof->top_addr = top_addr;
+
+    /* Find all predefined phandles */
+    for (offset = fdt_next_node(fdt, -1, NULL);
+         offset >= 0;
+         offset = fdt_next_node(fdt, offset, NULL)) {
+        prop = fdt_getprop(fdt, offset, "phandle", &proplen);
+        if (prop && proplen == sizeof(uint32_t)) {
+            phandle = fdt32_ld(prop);
+            g_array_append_val(phandles, phandle);
+        }
+    }
+
+    /* Assign phandles skipping the predefined ones */
+    for (offset = fdt_next_node(fdt, -1, NULL), phandle = 1;
+         offset >= 0;
+         offset = fdt_next_node(fdt, offset, NULL), ++phandle) {
+        prop = fdt_getprop(fdt, offset, "phandle", &proplen);
+        if (prop) {
+            continue;
+        }
+        /* Check if the current phandle is not allocated already */
+        for ( ; ; ++phandle) {
+            for (i = 0, found = false; i < phandles->len; ++i) {
+                if (phandle == g_array_index(phandles, uint32_t, i)) {
+                    found = true;
+                    break;
+                }
+            }
+            if (!found) {
+                break;
+            }
+        }
+        _FDT(fdt_setprop_cell(fdt, offset, "phandle", phandle));
+    }
+    g_array_unref(phandles);
+
+    vof_dt_memory_available(fdt, vof->claimed, vof->claimed_base);
+}
diff --git a/pc-bios/vof/bootmem.c b/pc-bios/vof/bootmem.c
new file mode 100644
index 000000000000..771b9e95f95d
--- /dev/null
+++ b/pc-bios/vof/bootmem.c
@@ -0,0 +1,14 @@
+#include "vof.h"
+
+void boot_from_memory(uint64_t initrd, uint64_t initrdsize)
+{
+    uint64_t kern[2];
+    phandle chosen = ci_finddevice("/chosen");
+
+    if (ci_getprop(chosen, "qemu,boot-kernel", kern, sizeof(kern)) !=
+        sizeof(kern)) {
+        return;
+    }
+
+    do_boot(kern[0], initrd, initrdsize);
+}
diff --git a/pc-bios/vof/ci.c b/pc-bios/vof/ci.c
new file mode 100644
index 000000000000..a80806580dd0
--- /dev/null
+++ b/pc-bios/vof/ci.c
@@ -0,0 +1,91 @@
+#include "vof.h"
+
+struct prom_args {
+    uint32_t service;
+    uint32_t nargs;
+    uint32_t nret;
+    uint32_t args[10];
+};
+
+typedef unsigned long prom_arg_t;
+
+#define ADDR(x) (uint32_t)(x)
+
+static int prom_handle(struct prom_args *pargs)
+{
+    void *rtasbase;
+    uint32_t rtassize = 0;
+    phandle rtas;
+
+    if (strcmp("call-method", (void *)(unsigned long) pargs->service)) {
+        return -1;
+    }
+
+    if (strcmp("instantiate-rtas", (void *)(unsigned long) pargs->args[0])) {
+        return -1;
+    }
+
+    rtas = ci_finddevice("/rtas");
+    /* rtas-size is set by QEMU depending of FWNMI support */
+    ci_getprop(rtas, "rtas-size", &rtassize, sizeof(rtassize));
+    if (rtassize < hv_rtas_size) {
+        return -1;
+    }
+
+    rtasbase = (void *)(unsigned long) pargs->args[2];
+
+    memcpy(rtasbase, hv_rtas, hv_rtas_size);
+    pargs->args[pargs->nargs] = 0;
+    pargs->args[pargs->nargs + 1] = pargs->args[2];
+
+    return 0;
+}
+
+void prom_entry(uint32_t args)
+{
+    if (prom_handle((void *)(unsigned long) args)) {
+        ci_entry(args);
+    }
+}
+
+static int call_ci(const char *service, int nargs, int nret, ...)
+{
+    int i;
+    struct prom_args args;
+    va_list list;
+
+    args.service = ADDR(service);
+    args.nargs = nargs;
+    args.nret = nret;
+
+    va_start(list, nret);
+    for (i = 0; i < nargs; i++) {
+        args.args[i] = va_arg(list, prom_arg_t);
+    }
+    va_end(list);
+
+    for (i = 0; i < nret; i++) {
+        args.args[nargs + i] = 0;
+    }
+
+    if (ci_entry((uint32_t)(&args)) < 0) {
+        return PROM_ERROR;
+    }
+
+    return (nret > 0) ? args.args[nargs] : 0;
+}
+
+void ci_panic(const char *str)
+{
+    call_ci("exit", 0, 0);
+}
+
+phandle ci_finddevice(const char *path)
+{
+    return call_ci("finddevice", 1, 1, path);
+}
+
+uint32_t ci_getprop(phandle ph, const char *propname, void *prop, int len)
+{
+    return call_ci("getprop", 4, 1, ph, propname, prop, len);
+}
diff --git a/pc-bios/vof/libc.c b/pc-bios/vof/libc.c
new file mode 100644
index 000000000000..00c10e6e7da1
--- /dev/null
+++ b/pc-bios/vof/libc.c
@@ -0,0 +1,92 @@
+#include "vof.h"
+
+int strlen(const char *s)
+{
+    int len = 0;
+
+    while (*s != 0) {
+        len += 1;
+        s += 1;
+    }
+
+    return len;
+}
+
+int strcmp(const char *s1, const char *s2)
+{
+    while (*s1 != 0 && *s2 != 0) {
+        if (*s1 != *s2) {
+            break;
+        }
+        s1 += 1;
+        s2 += 1;
+    }
+
+    return *s1 - *s2;
+}
+
+void *memcpy(void *dest, const void *src, size_t n)
+{
+    char *cdest;
+    const char *csrc = src;
+
+    cdest = dest;
+    while (n-- > 0) {
+        *cdest++ = *csrc++;
+    }
+
+    return dest;
+}
+
+int memcmp(const void *ptr1, const void *ptr2, size_t n)
+{
+    const unsigned char *p1 = ptr1;
+    const unsigned char *p2 = ptr2;
+
+    while (n-- > 0) {
+        if (*p1 != *p2) {
+            return *p1 - *p2;
+        }
+        p1 += 1;
+        p2 += 1;
+    }
+
+    return 0;
+}
+
+void *memmove(void *dest, const void *src, size_t n)
+{
+    char *cdest;
+    const char *csrc;
+    int i;
+
+    /* Do the buffers overlap in a bad way? */
+    if (src < dest && src + n >= dest) {
+        /* Copy from end to start */
+        cdest = dest + n - 1;
+        csrc = src + n - 1;
+        for (i = 0; i < n; i++) {
+            *cdest-- = *csrc--;
+        }
+    } else {
+        /* Normal copy is possible */
+        cdest = dest;
+        csrc = src;
+        for (i = 0; i < n; i++) {
+            *cdest++ = *csrc++;
+        }
+    }
+
+    return dest;
+}
+
+void *memset(void *dest, int c, size_t size)
+{
+    unsigned char *d = (unsigned char *)dest;
+
+    while (size-- > 0) {
+        *d++ = (unsigned char)c;
+    }
+
+    return dest;
+}
diff --git a/pc-bios/vof/main.c b/pc-bios/vof/main.c
new file mode 100644
index 000000000000..9fc30d2d0957
--- /dev/null
+++ b/pc-bios/vof/main.c
@@ -0,0 +1,21 @@
+#include "vof.h"
+
+void do_boot(unsigned long addr, unsigned long _r3, unsigned long _r4)
+{
+    register unsigned long r3 __asm__("r3") = _r3;
+    register unsigned long r4 __asm__("r4") = _r4;
+    register unsigned long r5 __asm__("r5") = (unsigned long) _prom_entry;
+
+    ((client *)(uint32_t)addr)();
+}
+
+void entry_c(void)
+{
+    register unsigned long r3 __asm__("r3");
+    register unsigned long r4 __asm__("r4");
+    register unsigned long r5 __asm__("r5");
+    uint64_t initrd = r3, initrdsize = r4;
+
+    boot_from_memory(initrd, initrdsize);
+    ci_panic("*** No boot target ***\n");
+}
diff --git a/MAINTAINERS b/MAINTAINERS
index 9147e9a429a0..cfad58685d91 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1366,6 +1366,17 @@ F: pc-bios/canyonlands.dt[sb]
 F: pc-bios/u-boot-sam460ex-20100605.bin
 F: roms/u-boot-sam460ex
 
+Virtual Open Firmware (VOF)
+M: Alexey Kardashevskiy <aik@ozlabs.ru>
+M: David Gibson <david@gibson.dropbear.id.au>
+M: Greg Kurz <groug@kaod.org>
+L: qemu-ppc@nongnu.org
+S: Maintained
+F: hw/ppc/spapr_vof*
+F: hw/ppc/vof*
+F: pc-bios/vof/*
+F: pc-bios/vof*
+
 RISC-V Machines
 ---------------
 OpenTitan
diff --git a/hw/ppc/meson.build b/hw/ppc/meson.build
index 218631c883be..24427d3f51c1 100644
--- a/hw/ppc/meson.build
+++ b/hw/ppc/meson.build
@@ -28,6 +28,8 @@ ppc_ss.add(when: 'CONFIG_PSERIES', if_true: files(
   'spapr_rtas_ddw.c',
   'spapr_numa.c',
   'pef.c',
+  'spapr_vof.c',
+  'vof.c',
 ))
 ppc_ss.add(when: 'CONFIG_SPAPR_RNG', if_true: files('spapr_rng.c'))
 ppc_ss.add(when: ['CONFIG_PSERIES', 'CONFIG_LINUX'], if_true: files(
diff --git a/hw/ppc/trace-events b/hw/ppc/trace-events
index b4bbfbb01348..da5e6809eba3 100644
--- a/hw/ppc/trace-events
+++ b/hw/ppc/trace-events
@@ -71,6 +71,30 @@ spapr_rtas_ibm_configure_connector_invalid(uint32_t index) "DRC index: 0x%"PRIx3
 spapr_vio_h_reg_crq(uint64_t reg, uint64_t queue_addr, uint64_t queue_len) "CRQ for dev 0x%" PRIx64 " registered at 0x%" PRIx64 "/0x%" PRIx64
 spapr_vio_free_crq(uint32_t reg) "CRQ for dev 0x%" PRIx32 " freed"
 
+# vof.c
+vof_error_str_truncated(const char *s, int len) "%s truncated to %d"
+vof_error_param(const char *method, int nargscheck, int nretcheck, int nargs, int nret) "%s takes/returns %d/%d, not %d/%d"
+vof_error_unknown_service(const char *service, int nargs, int nret) "\"%s\" args=%d rets=%d"
+vof_error_unknown_method(const char *method) "\"%s\""
+vof_error_unknown_ihandle_close(uint32_t ih) "ih=0x%x"
+vof_error_unknown_path(const char *path) "\"%s\""
+vof_error_write(uint32_t ih) "ih=0x%x"
+vof_finddevice(const char *path, uint32_t ph) "\"%s\" => ph=0x%x"
+vof_claim(uint32_t virt, uint32_t size, uint32_t align, uint32_t ret) "virt=0x%x size=0x%x align=0x%x => 0x%x"
+vof_release(uint32_t virt, uint32_t size, uint32_t ret) "virt=0x%x size=0x%x => 0x%x"
+vof_method(uint32_t ihandle, const char *method, uint32_t param, uint32_t ret, uint32_t ret2) "ih=0x%x \"%s\"(0x%x) => 0x%x 0x%x"
+vof_getprop(uint32_t ph, const char *prop, uint32_t ret, const char *val) "ph=0x%x \"%s\" => len=%d [%s]"
+vof_getproplen(uint32_t ph, const char *prop, uint32_t ret) "ph=0x%x \"%s\" => len=%d"
+vof_setprop(uint32_t ph, const char *prop, const char *val, uint32_t vallen, uint32_t ret) "ph=0x%x \"%s\" [%s] len=%d => ret=%d"
+vof_open(const char *path, uint32_t ph, uint32_t ih) "%s ph=0x%x => ih=0x%x"
+vof_interpret(const char *cmd, uint32_t param1, uint32_t param2, uint32_t ret, uint32_t ret2) "[%s] 0x%x 0x%x => 0x%x 0x%x"
+vof_package_to_path(uint32_t ph, const char *tmp, uint32_t ret) "ph=0x%x => %s len=%d"
+vof_instance_to_path(uint32_t ih, uint32_t ph, const char *tmp, uint32_t ret) "ih=0x%x ph=0x%x => %s len=%d"
+vof_instance_to_package(uint32_t ih, uint32_t ph) "ih=0x%x => ph=0x%x"
+vof_write(uint32_t ih, unsigned cb, const char *msg) "ih=0x%x [%u] \"%s\""
+vof_avail(uint64_t start, uint64_t end, uint64_t size) "0x%"PRIx64"..0x%"PRIx64" size=%"PRId64
+vof_claimed(uint64_t start, uint64_t end, uint64_t size) "0x%"PRIx64"..0x%"PRIx64" size=%"PRId64
+
 # ppc.c
 ppc_tb_adjust(uint64_t offs1, uint64_t offs2, int64_t diff, int64_t seconds) "adjusted from 0x%"PRIx64" to 0x%"PRIx64", diff %"PRId64" (%"PRId64"s)"
 
diff --git a/pc-bios/README b/pc-bios/README
index c101c9a04f8f..6e6556e91c92 100644
--- a/pc-bios/README
+++ b/pc-bios/README
@@ -16,6 +16,8 @@
   https://github.com/aik/SLOF, and the image currently in qemu is
   built from git tag qemu-slof-20210217.
 
+- vof is a minimalistic firmware to work with -machine pseries,x-vof=on.
+
 - sgabios (the Serial Graphics Adapter option ROM) provides a means for
   legacy x86 software to communicate with an attached serial console as
   if a video card were attached.  The master sources reside in a subversion
diff --git a/pc-bios/vof-nvram.bin b/pc-bios/vof-nvram.bin
new file mode 100644
index 0000000000000000000000000000000000000000..d183901cf980a91d81c4348bb20487c7bb62a2ec
GIT binary patch
literal 16384
zcmeI%Jx;?g6bEpZJ8*)oSZeqZi&Z2pKnD)sI4{AHlNb4;RW}a70XPHaW57uo=-#R7
zKSLBhJJ0sdixY3IuY@hzo0r$OmE%T;XE9uh@s1k=AOHafKmY;|fB*y_009U<00Izz
z00bZa0SG_<0uX=z1Rwwb2tWV=XCbip6d#B4{{rX#XR%}$Bm^J;0SG|gWP$!?Aq=-I
zcT+0Ix{{?1q>9J8r+eW^JK1tYYZZMWQCUwW%0S*~w^p@wfkX-<yRFx)H*+YEt0RRd
zmn}6xtwbP`yp4O=>kxMAEA<~5@*g)@mb%KD5!;O~8c)>8rRQBx55=trhk#+1+T3J_
zaf*G4vZAduqy$qda{``6Gnc2DQg<Es<GLxL#9<Oj*zP!8ZSnwf@-j7l47!nFXQO$a
z^Hes6YU^_M<KsM*k~zwOSa+2g3Sx{*Eyu^XrB0FM5IJ-*?8`VvpBc4}vS(+_UKJ;=
xITAns0uX=z1Rwwb2tWV=5P-nt34DD||Nni|VfbXeJORuY0uX=z1R!vE0>7B^s4f5i

literal 0
HcmV?d00001

diff --git a/pc-bios/vof.bin b/pc-bios/vof.bin
new file mode 100755
index 0000000000000000000000000000000000000000..f52e8e6a6da36791cbc97ecc420c7a41fe8e76f0
GIT binary patch
literal 3128
zcmd^AO=ufe5FS}_yQy{9gARhIc-^>QsWx`O2XAYlb?Sg@2V+PLhPp_KrPiXh<=Sf5
z7O7e_O&X;wNF;>>VmpT*(nBGK9FkL9D8*18e8@q8Hg=!~LoPWcr0MpX-M6tKC#opD
zRq%ML_h#ptpKrb;`hWkzJ47=kQGUmj7}SVjN4}v5(WdkKu){1rzDKk9-Ihv(TE2^+
zT=`vh<vz{^I%sj+ASIhPs1M>IHuIo$nCP{-Gjh)Gs_%S<xs{b#DkT^7pZkfr&fTN#
zY`9H7vPP}>jh0IIF1g;mdsZ*yNh+<8w{(kSBTrsqjpV{%gL1Er>4h*!xuCl;Zg@I4
z9yL#WMjLsulDl&9SM%Y?`{tjy_<K6X(IlRfO&!$BVe+a95q2qCJjDNf;=gQg9NXkW
zED~bzM#%HX_`>i+$o<2A6GQP^<m`9wkfXm4B+7M;>A*oxTEFKQdy7Ovs~o3kqEEjG
zJFl=qJgxK3vAYf*5@LOy>#BxH9#|(2*V0%uyqpu~QHWYKmKisHHlk^lp5kN#j*n}E
zK3F#5eXa@W(OMQZ9{BN32IaSMp;4b2gbxih9U*e=apq#1!YKI)?ZURpwq-l6LGI9)
z{ttcK5j^SykNn_KU_Xz}3~;`{mDt~y`PXN)wL#p{nEB+W=%3PnLwy44Hn28;wYeYb
z>rG%yfwR-#Y^=0Rb0w1&%k7jw&Gd4Vvf63ttcJ;`M(Ip7Po?S_U8vro%hheVS~cm~
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z=WDS0aW{=SiF<GPfvw<yT*HHUUoqk9XXN9xd-eE7&Yk(Lt&qZa_5PTr$U$O!!I!ND
zJ#2z6rzPggz-6KVg9tO@KlaO;UxGKT7+E^gh$Bt-KXsM;Lq{0H1q>H30yf5z73QYM
zqY+LM`guxY97jLFMIY+NvnCrRv~&;O1AIl`zgmOeNKdbcS$G$-5Wy@Q+dm6m{Q>+g
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zockTj@}ryFd(oGP27TXhzA?ad^p)o%0Ka=Y4CBt`w;$*JBDiI7Z`EXtwe*AasP5ac
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z4Xv14{Jy}|n#8s69DLwT;CWx2kUz&Laoy_kbZYxlhmc224eMjPQlksa#Td0}?-$>`
z65>!$n*i$<cIzCP%6wGRplR|M-&vZtcV^jhjfF1Ch`Z0OF=}YnUQ!R>`PmxFA{XX8
z>#`y=aRcwOran`@{k|La?}fhE@4x9IVzTFF1h`S_n-G{B#rNg;e5t+&Clm@P<7wqY
zI-OB6@ud%w83jkL&`f-8u4g`(nN24swXmFtFJw~jOtNPw6JLfDQ?Gd7t!Fv)c@k$y
zJ(c0R4^j(>MDo+r3=ZLNaVfn>y)(1v<>Uf=oSgrpo6&kcN-ixV=h&Xe<tJ)0ur6R-
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literal 0
HcmV?d00001

diff --git a/pc-bios/vof/entry.S b/pc-bios/vof/entry.S
new file mode 100644
index 000000000000..90f4b859a059
--- /dev/null
+++ b/pc-bios/vof/entry.S
@@ -0,0 +1,51 @@
+#define LOAD32(rn, name)    \
+	lis     rn,name##@h;    \
+	ori     rn,rn,name##@l
+
+#define ENTRY(func_name)    \
+	.text;                  \
+	.align  2;              \
+	.globl  .func_name;     \
+	.func_name:             \
+	.globl  func_name;      \
+	func_name:
+
+#define KVMPPC_HCALL_BASE       0xf000
+#define KVMPPC_H_RTAS           (KVMPPC_HCALL_BASE + 0x0)
+#define KVMPPC_H_VOF_CLIENT     (KVMPPC_HCALL_BASE + 0x5)
+
+	. = 0x100 /* Do exactly as SLOF does */
+
+ENTRY(_start)
+	LOAD32(%r31, 0) /* Go 32bit mode */
+	mtmsrd %r31,0
+	LOAD32(2, __toc_start)
+	b entry_c
+
+ENTRY(_prom_entry)
+	LOAD32(2, __toc_start)
+	stdu    %r1,-112(%r1)
+	std     %r31,104(%r1)
+	mflr    %r31
+	bl prom_entry
+	nop
+	mtlr    %r31
+	ld      %r31,104(%r1)
+	addi    %r1,%r1,112
+	blr
+
+ENTRY(ci_entry)
+	mr	4,3
+	LOAD32(3,KVMPPC_H_VOF_CLIENT)
+	sc	1
+	blr
+
+/* This is the actual RTAS blob copied to the OS at instantiate-rtas */
+ENTRY(hv_rtas)
+	mr      %r4,%r3
+	LOAD32(3,KVMPPC_H_RTAS)
+	sc	1
+	blr
+	.globl hv_rtas_size
+hv_rtas_size:
+	.long . - hv_rtas;
diff --git a/pc-bios/vof/l.lds b/pc-bios/vof/l.lds
new file mode 100644
index 000000000000..10b557a81f78
--- /dev/null
+++ b/pc-bios/vof/l.lds
@@ -0,0 +1,48 @@
+OUTPUT_FORMAT("elf32-powerpc", "elf32-powerpc", "elf32-powerpc")
+OUTPUT_ARCH(powerpc:common)
+
+/* set the entry point */
+ENTRY ( __start )
+
+SECTIONS {
+	__executable_start = .;
+
+	.text : {
+		*(.text)
+	}
+
+	__etext = .;
+
+	. = ALIGN(8);
+
+	.data : {
+		*(.data)
+		*(.rodata .rodata.*)
+		*(.got1)
+		*(.sdata)
+		*(.opd)
+	}
+
+	/* FIXME bss at end ??? */
+
+	. = ALIGN(8);
+	__bss_start = .;
+	.bss : {
+		*(.sbss) *(.scommon)
+		*(.dynbss)
+		*(.bss)
+	}
+
+	. = ALIGN(8);
+	__bss_end = .;
+	__bss_size = (__bss_end - __bss_start);
+
+	. = ALIGN(256);
+	__toc_start = DEFINED (.TOC.) ? .TOC. : ADDR (.got) + 0x8000;
+	.got :
+	{
+		 *(.toc .got)
+	}
+	. = ALIGN(8);
+	__toc_end = .;
+}
-- 
2.17.1



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