[PATCH v5 00/14] QMP/HMP: introduce 'dumpdtb'

[PATCH v5 00/14] QMP/HMP: introduce 'dumpdtb'

[Daniel Henrique Barboza]

Hi,

In this version I removed the 'info fdt' command. It didn't get enough
traction/acceptance to justify the amount of code to implement it.

Aside from that, all other changes are based on Markus' feedback on
patch 14.

Changes from v4:
- patches 15-21: removed
- patch 14:
  - dumpdtb is now dependent on 'if: CONFIG_FDT' in qapi/machine.json
  - dumpdtb is now dependent on 'if defined(CONFIG_FDT)' in hmp-commands.hx
  - moved qmp_dumpdtb() and hmp_dumpdtb() to device_tree.c
  - added a GError pointer to g_file_set_contents() to report errors caught
  - hmp_handle_error() is now called unconditionally
- v4 link: https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg04115.html


Daniel Henrique Barboza (14):
  hw/arm: do not free machine->fdt in arm_load_dtb()
  hw/microblaze: set machine->fdt in microblaze_load_dtb()
  hw/nios2: set machine->fdt in nios2_load_dtb()
  hw/ppc: set machine->fdt in ppce500_load_device_tree()
  hw/ppc: set machine->fdt in bamboo_load_device_tree()
  hw/ppc: set machine->fdt in sam460ex_load_device_tree()
  hw/ppc: set machine->fdt in xilinx_load_device_tree()
  hw/ppc: set machine->fdt in pegasos2_machine_reset()
  hw/ppc: set machine->fdt in pnv_reset()
  hw/ppc: set machine->fdt in spapr machine
  hw/riscv: set machine->fdt in sifive_u_machine_init()
  hw/riscv: set machine->fdt in spike_board_init()
  hw/xtensa: set machine->fdt in xtfpga_init()
  qmp/hmp, device_tree.c: introduce dumpdtb

 hmp-commands.hx              | 15 +++++++++++++++
 hw/arm/boot.c                |  3 ++-
 hw/microblaze/boot.c         |  8 +++++++-
 hw/microblaze/meson.build    |  2 +-
 hw/nios2/boot.c              |  8 +++++++-
 hw/nios2/meson.build         |  2 +-
 hw/ppc/e500.c                | 13 ++++++++++++-
 hw/ppc/pegasos2.c            |  7 +++++++
 hw/ppc/pnv.c                 |  8 +++++++-
 hw/ppc/ppc440_bamboo.c       | 11 ++++++++++-
 hw/ppc/sam460ex.c            |  5 ++++-
 hw/ppc/spapr.c               |  6 ++++++
 hw/ppc/spapr_hcall.c         |  8 ++++++++
 hw/ppc/virtex_ml507.c        | 11 ++++++++++-
 hw/riscv/sifive_u.c          |  6 ++++++
 hw/riscv/spike.c             |  9 +++++++++
 hw/xtensa/meson.build        |  2 +-
 hw/xtensa/xtfpga.c           |  9 ++++++++-
 include/sysemu/device_tree.h |  1 +
 monitor/misc.c               |  1 +
 qapi/machine.json            | 18 ++++++++++++++++++
 softmmu/device_tree.c        | 31 +++++++++++++++++++++++++++++++
 22 files changed, 172 insertions(+), 12 deletions(-)

-- 
2.37.2

[PATCH v5 01/14] hw/arm: do not free machine->fdt in arm_load_dtb()

[Daniel Henrique Barboza]

At this moment, arm_load_dtb() can free machine->fdt when
binfo->dtb_filename is NULL. If there's no 'dtb_filename', 'fdt' will be
retrieved by binfo->get_dtb(). If get_dtb() returns machine->fdt, as is
the case of machvirt_dtb() from hw/arm/virt.c, fdt now has a pointer to
machine->fdt. And, in that case, the existing g_free(fdt) at the end of
arm_load_dtb() will make machine->fdt point to an invalid memory region.

This is not an issue right now because there's no code that access
machine->fdt after arm_load_dtb(), but we're going to add a QMP/HMP
FDT command that will rely on machine->fdt being valid.

Instead of freeing 'fdt' at the end of arm_load_dtb(), assign it to
machine->fdt. This will allow the FDT of ARM machines that relies on
arm_load_dtb() to be accessed later on.

Since all ARM machines allocates the FDT only once, we don't need to
worry about leaking the existing FDT during a machine reset (which is
something that other machines have to look after, e.g. the ppc64 pSeries
machine).

Cc: Peter Maydell <peter.maydell@linaro.org>
Cc: qemu-arm@nongnu.org
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/arm/boot.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hw/arm/boot.c b/hw/arm/boot.c
index ada2717f76..60bbfba37f 100644
--- a/hw/arm/boot.c
+++ b/hw/arm/boot.c
@@ -684,7 +684,8 @@ int arm_load_dtb(hwaddr addr, const struct arm_boot_info *binfo,
      */
     rom_add_blob_fixed_as("dtb", fdt, size, addr, as);
 
-    g_free(fdt);
+    /* Set ms->fdt for 'dumpdtb' QMP/HMP command */
+    ms->fdt = fdt;
 
     return size;
 
-- 
2.37.2

[PATCH v5 02/14] hw/microblaze: set machine->fdt in microblaze_load_dtb()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for all
microblaze machines that uses microblaze_load_dtb().

Cc: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/microblaze/boot.c      | 8 +++++++-
 hw/microblaze/meson.build | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/hw/microblaze/boot.c b/hw/microblaze/boot.c
index 8b92a9801a..c8eff7b6fc 100644
--- a/hw/microblaze/boot.c
+++ b/hw/microblaze/boot.c
@@ -39,6 +39,8 @@
 
 #include "boot.h"
 
+#include <libfdt.h>
+
 static struct
 {
     void (*machine_cpu_reset)(MicroBlazeCPU *);
@@ -72,6 +74,7 @@ static int microblaze_load_dtb(hwaddr addr,
                                const char *kernel_cmdline,
                                const char *dtb_filename)
 {
+    MachineState *machine = MACHINE(qdev_get_machine());
     int fdt_size;
     void *fdt = NULL;
     int r;
@@ -100,7 +103,10 @@ static int microblaze_load_dtb(hwaddr addr,
     }
 
     cpu_physical_memory_write(addr, fdt, fdt_size);
-    g_free(fdt);
+
+    /* Set machine->fdt for 'dumpdtb' QMP/HMP command */
+    machine->fdt = fdt;
+
     return fdt_size;
 }
 
diff --git a/hw/microblaze/meson.build b/hw/microblaze/meson.build
index bb9e4eb8f4..a38a397872 100644
--- a/hw/microblaze/meson.build
+++ b/hw/microblaze/meson.build
@@ -1,5 +1,5 @@
 microblaze_ss = ss.source_set()
-microblaze_ss.add(files('boot.c'))
+microblaze_ss.add(files('boot.c'), fdt)
 microblaze_ss.add(when: 'CONFIG_PETALOGIX_S3ADSP1800', if_true: files('petalogix_s3adsp1800_mmu.c'))
 microblaze_ss.add(when: 'CONFIG_PETALOGIX_ML605', if_true: files('petalogix_ml605_mmu.c'))
 microblaze_ss.add(when: 'CONFIG_XLNX_ZYNQMP_PMU', if_true: files('xlnx-zynqmp-pmu.c'))
-- 
2.37.2

[PATCH v5 03/14] hw/nios2: set machine->fdt in nios2_load_dtb()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for all nios2
machines that uses nios2_load_dtb().

Cc: Chris Wulff <crwulff@gmail.com>
Cc: Marek Vasut <marex@denx.de>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/nios2/boot.c      | 8 +++++++-
 hw/nios2/meson.build | 2 +-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/hw/nios2/boot.c b/hw/nios2/boot.c
index 21cbffff47..b30a7b1efb 100644
--- a/hw/nios2/boot.c
+++ b/hw/nios2/boot.c
@@ -43,6 +43,8 @@
 
 #include "boot.h"
 
+#include <libfdt.h>
+
 #define NIOS2_MAGIC    0x534f494e
 
 static struct nios2_boot_info {
@@ -81,6 +83,7 @@ static uint64_t translate_kernel_address(void *opaque, uint64_t addr)
 static int nios2_load_dtb(struct nios2_boot_info bi, const uint32_t ramsize,
                           const char *kernel_cmdline, const char *dtb_filename)
 {
+    MachineState *machine = MACHINE(qdev_get_machine());
     int fdt_size;
     void *fdt = NULL;
     int r;
@@ -113,7 +116,10 @@ static int nios2_load_dtb(struct nios2_boot_info bi, const uint32_t ramsize,
     }
 
     cpu_physical_memory_write(bi.fdt, fdt, fdt_size);
-    g_free(fdt);
+
+    /* Set machine->fdt for 'dumpdtb' QMP/HMP command */
+    machine->fdt = fdt;
+
     return fdt_size;
 }
 
diff --git a/hw/nios2/meson.build b/hw/nios2/meson.build
index 6c58e8082b..22277bd6c5 100644
--- a/hw/nios2/meson.build
+++ b/hw/nios2/meson.build
@@ -1,5 +1,5 @@
 nios2_ss = ss.source_set()
-nios2_ss.add(files('boot.c'))
+nios2_ss.add(files('boot.c'), fdt)
 nios2_ss.add(when: 'CONFIG_NIOS2_10M50', if_true: files('10m50_devboard.c'))
 nios2_ss.add(when: 'CONFIG_NIOS2_GENERIC_NOMMU', if_true: files('generic_nommu.c'))
 
-- 
2.37.2

[PATCH v5 04/14] hw/ppc: set machine->fdt in ppce500_load_device_tree()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for the e500
machine.

Cc: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/e500.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
index 32495d0123..ea5f947824 100644
--- a/hw/ppc/e500.c
+++ b/hw/ppc/e500.c
@@ -47,6 +47,8 @@
 #include "hw/i2c/i2c.h"
 #include "hw/irq.h"
 
+#include <libfdt.h>
+
 #define EPAPR_MAGIC                (0x45504150)
 #define DTC_LOAD_PAD               0x1800000
 #define DTC_PAD_MASK               0xFFFFF
@@ -600,7 +602,16 @@ done:
         cpu_physical_memory_write(addr, fdt, fdt_size);
     }
     ret = fdt_size;
-    g_free(fdt);
+
+    /*
+     * Update the machine->fdt pointer to enable support for the
+     * 'dumpdtb' QMP/HMP command.
+     *
+     * The FDT is re-created during reset, so free machine->fdt
+     * to avoid leaking the old FDT.
+     */
+    g_free(machine->fdt);
+    machine->fdt = fdt;
 
 out:
     g_free(pci_map);
-- 
2.37.2

[PATCH v5 05/14] hw/ppc: set machine->fdt in bamboo_load_device_tree()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for the bamboo
machine.

Cc: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/ppc440_bamboo.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/ppc440_bamboo.c b/hw/ppc/ppc440_bamboo.c
index ea945a1c99..aa5c901b09 100644
--- a/hw/ppc/ppc440_bamboo.c
+++ b/hw/ppc/ppc440_bamboo.c
@@ -34,6 +34,8 @@
 #include "hw/qdev-properties.h"
 #include "qapi/error.h"
 
+#include <libfdt.h>
+
 #define BINARY_DEVICE_TREE_FILE "bamboo.dtb"
 
 /* from u-boot */
@@ -62,6 +64,7 @@ static int bamboo_load_device_tree(hwaddr addr,
                                      hwaddr initrd_size,
                                      const char *kernel_cmdline)
 {
+    MachineState *machine = MACHINE(qdev_get_machine());
     int ret = -1;
     uint32_t mem_reg_property[] = { 0, 0, cpu_to_be32(ramsize) };
     char *filename;
@@ -119,7 +122,13 @@ static int bamboo_load_device_tree(hwaddr addr,
                           tb_freq);
 
     rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
-    g_free(fdt);
+
+    /*
+     * Update the machine->fdt pointer to enable support for
+     * 'dumpdtb' QMP/HMP command.
+     */
+    machine->fdt = fdt;
+
     return 0;
 }
 
-- 
2.37.2

[PATCH v5 06/14] hw/ppc: set machine->fdt in sam460ex_load_device_tree()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for the sam460ex
machine.

Cc: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/sam460ex.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
index 850bb3b817..fa6f125fda 100644
--- a/hw/ppc/sam460ex.c
+++ b/hw/ppc/sam460ex.c
@@ -137,6 +137,7 @@ static int sam460ex_load_device_tree(hwaddr addr,
                                      hwaddr initrd_size,
                                      const char *kernel_cmdline)
 {
+    MachineState *machine = MACHINE(qdev_get_machine());
     uint32_t mem_reg_property[] = { 0, 0, cpu_to_be32(ramsize) };
     char *filename;
     int fdt_size;
@@ -208,7 +209,9 @@ static int sam460ex_load_device_tree(hwaddr addr,
                               EBC_FREQ);
 
     rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
-    g_free(fdt);
+
+    /* Set machine->fdt for 'dumpdtb' QMP/HMP command */
+    machine->fdt = fdt;
 
     return fdt_size;
 }
-- 
2.37.2

[PATCH v5 07/14] hw/ppc: set machine->fdt in xilinx_load_device_tree()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for the
virtex_ml507 machine.

Cc: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/virtex_ml507.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/virtex_ml507.c b/hw/ppc/virtex_ml507.c
index 493ea0c19f..bb21b2a309 100644
--- a/hw/ppc/virtex_ml507.c
+++ b/hw/ppc/virtex_ml507.c
@@ -45,6 +45,8 @@
 #include "hw/qdev-properties.h"
 #include "ppc405.h"
 
+#include <libfdt.h>
+
 #define EPAPR_MAGIC    (0x45504150)
 #define FLASH_SIZE     (16 * MiB)
 
@@ -150,6 +152,7 @@ static int xilinx_load_device_tree(hwaddr addr,
                                       hwaddr initrd_size,
                                       const char *kernel_cmdline)
 {
+    MachineState *machine = MACHINE(qdev_get_machine());
     char *path;
     int fdt_size;
     void *fdt = NULL;
@@ -194,7 +197,13 @@ static int xilinx_load_device_tree(hwaddr addr,
     if (r < 0)
         fprintf(stderr, "couldn't set /chosen/bootargs\n");
     cpu_physical_memory_write(addr, fdt, fdt_size);
-    g_free(fdt);
+
+    /*
+     * Update the machine->fdt pointer to enable support for
+     * 'dumpdtb'QMP/HMP command.
+     */
+    machine->fdt = fdt;
+
     return fdt_size;
 }
 
-- 
2.37.2

[PATCH v5 08/14] hw/ppc: set machine->fdt in pegasos2_machine_reset()

[Daniel Henrique Barboza]

We'll introduce a QMP/HMP command that requires machine->fdt to be set
properly.

Cc: BALATON Zoltan <balaton@eik.bme.hu>
Cc: qemu-ppc@nongnu.org
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/pegasos2.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/ppc/pegasos2.c b/hw/ppc/pegasos2.c
index 61f4263953..d7ea139ff4 100644
--- a/hw/ppc/pegasos2.c
+++ b/hw/ppc/pegasos2.c
@@ -331,6 +331,13 @@ static void pegasos2_machine_reset(MachineState *machine)
 
     vof_build_dt(fdt, pm->vof);
     vof_client_open_store(fdt, pm->vof, "/chosen", "stdout", "/failsafe");
+
+    /*
+     * Set the common machine->fdt pointer to enable support
+     * for 'dumpdtb' QMP/HMP command.
+     */
+    machine->fdt = fdt;
+
     pm->cpu->vhyp = PPC_VIRTUAL_HYPERVISOR(machine);
 }
 
-- 
2.37.2

[PATCH v5 09/14] hw/ppc: set machine->fdt in pnv_reset()

[Daniel Henrique Barboza]

This will enable support for the 'dumpdtb' QMP/HMP command for
all powernv machines.

Cc: Cédric Le Goater <clg@kaod.org>
Cc: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/pnv.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c
index 354aa289d1..afd90d261b 100644
--- a/hw/ppc/pnv.c
+++ b/hw/ppc/pnv.c
@@ -678,7 +678,13 @@ static void pnv_reset(MachineState *machine)
     qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt));
     cpu_physical_memory_write(PNV_FDT_ADDR, fdt, fdt_totalsize(fdt));
 
-    g_free(fdt);
+    /*
+     * Update the machine->fdt pointer to enable support for
+     * 'dumpdtb' QMP/HMP command. Free the existing machine->fdt
+     * to avoid leaking it during a reset.
+     */
+    g_free(machine->fdt);
+    machine->fdt = fdt;
 }
 
 static ISABus *pnv_chip_power8_isa_create(PnvChip *chip, Error **errp)
-- 
2.37.2

[PATCH v5 10/14] hw/ppc: set machine->fdt in spapr machine

[Daniel Henrique Barboza]

The pSeries machine never bothered with the common machine->fdt
attribute. We do all the FDT related work using spapr->fdt_blob.

We're going to introduce a QMP/HMP command to dump the FDT, which will
rely on setting machine->fdt properly to work across all machine
archs/types.

Let's set machine->fdt in two places where we manipulate the FDT:
spapr_machine_reset() and CAS. There are other places where the FDT is
manipulated in the pSeries machines, most notably the hotplug/unplug
path. For now we'll acknowledge that we won't have the most accurate
representation of the FDT, depending on the current machine state, when
using this QMP/HMP fdt command. Making the internal FDT representation
always match the actual FDT representation that the guest is using is a
problem for another day.

spapr->fdt_blob is left untouched for now. To replace it with
machine->fdt, since we're migrating spapr->fdt_blob, we would need to
migrate machine->fdt as well. This is something that we would like to to
do keep our code simpler but it's also a work we'll leave for later.

Cc: Cédric Le Goater <clg@kaod.org>
Cc: qemu-ppc@nongnu.org
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/ppc/spapr.c       | 6 ++++++
 hw/ppc/spapr_hcall.c | 8 ++++++++
 2 files changed, 14 insertions(+)

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index fb790b61e4..f0e5144d83 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -1713,6 +1713,12 @@ static void spapr_machine_reset(MachineState *machine)
     spapr->fdt_initial_size = spapr->fdt_size;
     spapr->fdt_blob = fdt;
 
+    /*
+     * Set the common machine->fdt pointer to enable support
+     * for the 'dumpdtb' QMP/HMP command.
+     */
+    machine->fdt = fdt;
+
     /* Set up the entry state */
     first_ppc_cpu->env.gpr[5] = 0;
 
diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
index a8d4a6bcf0..891206e893 100644
--- a/hw/ppc/spapr_hcall.c
+++ b/hw/ppc/spapr_hcall.c
@@ -1256,6 +1256,14 @@ target_ulong do_client_architecture_support(PowerPCCPU *cpu,
     spapr->fdt_initial_size = spapr->fdt_size;
     spapr->fdt_blob = fdt;
 
+    /*
+     * Set the machine->fdt pointer again since we just freed
+     * it above (by freeing spapr->fdt_blob). We set this
+     * pointer to enable support for the 'dumpdtb' QMP/HMP
+     * command.
+     */
+    MACHINE(spapr)->fdt = fdt;
+
     return H_SUCCESS;
 }
 
-- 
2.37.2

[PATCH v5 11/14] hw/riscv: set machine->fdt in sifive_u_machine_init()

[Daniel Henrique Barboza]

This will enable support for 'dumpdtb' QMP/HMP command for the sifive_u
machine.

Cc: Alistair Francis <Alistair.Francis@wdc.com>
Cc: Bin Meng <bin.meng@windriver.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/riscv/sifive_u.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/hw/riscv/sifive_u.c b/hw/riscv/sifive_u.c
index e4c814a3ea..07e25d0740 100644
--- a/hw/riscv/sifive_u.c
+++ b/hw/riscv/sifive_u.c
@@ -634,6 +634,12 @@ static void sifive_u_machine_init(MachineState *machine)
         start_addr_hi32 = (uint64_t)start_addr >> 32;
     }
 
+    /*
+     * Update the machine->fdt pointer to enable support for
+     * the 'dumpdtb' QMP/HMP command.
+     */
+    machine->fdt = s->fdt;
+
     /* reset vector */
     uint32_t reset_vec[12] = {
         s->msel,                       /* MSEL pin state */
-- 
2.37.2

[PATCH v5 12/14] hw/riscv: set machine->fdt in spike_board_init()

[Daniel Henrique Barboza]

This will enable support for the 'dumpdtb' QMP/HMP command for the spike
machine.

Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Alistair Francis <alistair.francis@wdc.com>
Cc: Bin Meng <bin.meng@windriver.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/riscv/spike.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/hw/riscv/spike.c b/hw/riscv/spike.c
index e41b6aa9f0..1fa41164b3 100644
--- a/hw/riscv/spike.c
+++ b/hw/riscv/spike.c
@@ -40,6 +40,8 @@
 #include "sysemu/device_tree.h"
 #include "sysemu/sysemu.h"
 
+#include <libfdt.h>
+
 static const MemMapEntry spike_memmap[] = {
     [SPIKE_MROM] =     {     0x1000,     0xf000 },
     [SPIKE_HTIF] =     {  0x1000000,     0x1000 },
@@ -304,6 +306,13 @@ static void spike_board_init(MachineState *machine)
     /* Compute the fdt load address in dram */
     fdt_load_addr = riscv_load_fdt(memmap[SPIKE_DRAM].base,
                                    machine->ram_size, s->fdt);
+
+    /*
+     * Update the machine->fdt pointer to enable support for
+     * the 'dumpdtb' QMP/HMP command.
+     */
+    machine->fdt = s->fdt;
+
     /* load the reset vector */
     riscv_setup_rom_reset_vec(machine, &s->soc[0], memmap[SPIKE_DRAM].base,
                               memmap[SPIKE_MROM].base,
-- 
2.37.2

[PATCH v5 13/14] hw/xtensa: set machine->fdt in xtfpga_init()

[Daniel Henrique Barboza]

This will enable support for the 'dumpdtb' QMP/HMP command for all
xtensa machines that uses a FDT.

Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/xtensa/meson.build | 2 +-
 hw/xtensa/xtfpga.c    | 9 ++++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/hw/xtensa/meson.build b/hw/xtensa/meson.build
index 1d5835df4b..ebba51cc74 100644
--- a/hw/xtensa/meson.build
+++ b/hw/xtensa/meson.build
@@ -6,6 +6,6 @@ xtensa_ss.add(files(
 ))
 xtensa_ss.add(when: 'CONFIG_XTENSA_SIM', if_true: files('sim.c'))
 xtensa_ss.add(when: 'CONFIG_XTENSA_VIRT', if_true: files('virt.c'))
-xtensa_ss.add(when: 'CONFIG_XTENSA_XTFPGA', if_true: files('xtfpga.c'))
+xtensa_ss.add(when: 'CONFIG_XTENSA_XTFPGA', if_true: [files('xtfpga.c'), fdt])
 
 hw_arch += {'xtensa': xtensa_ss}
diff --git a/hw/xtensa/xtfpga.c b/hw/xtensa/xtfpga.c
index 2a5556a35f..138453628a 100644
--- a/hw/xtensa/xtfpga.c
+++ b/hw/xtensa/xtfpga.c
@@ -50,6 +50,8 @@
 #include "hw/xtensa/mx_pic.h"
 #include "migration/vmstate.h"
 
+#include <libfdt.h>
+
 typedef struct XtfpgaFlashDesc {
     hwaddr base;
     size_t size;
@@ -377,7 +379,12 @@ static void xtfpga_init(const XtfpgaBoardDesc *board, MachineState *machine)
             cur_tagptr = put_tag(cur_tagptr, BP_TAG_FDT,
                                  sizeof(dtb_addr), &dtb_addr);
             cur_lowmem = QEMU_ALIGN_UP(cur_lowmem + fdt_size, 4 * KiB);
-            g_free(fdt);
+
+            /*
+             * Update the machine->fdt pointer to enable support for
+             * the 'dumpdtb' QMP/HMP command.
+             */
+            machine->fdt = fdt;
         }
 #else
         if (dtb_filename) {
-- 
2.37.2

[PATCH v5 14/14] qmp/hmp, device_tree.c: introduce dumpdtb

[Daniel Henrique Barboza]

To save the FDT blob we have the '-machine dumpdtb=<file>' property.
With this property set, the machine saves the FDT in <file> and exit.
The created file can then be converted to plain text dts format using
'dtc'.

There's nothing particularly sophisticated into saving the FDT that
can't be done with the machine at any state, as long as the machine has
a valid FDT to be saved.

The 'dumpdtb' command receives a 'filename' paramenter and, if a valid
FDT is available, it'll save it in a file 'filename'. In short, this is
a '-machine dumpdtb' that can be fired on demand via QMP/HMP.

A valid FDT consists of a FDT that was created using libfdt being
retrieved via 'current_machine->fdt' in device_tree.c. This condition is
met by most FDT users in QEMU.

This command will always be executed in-band (i.e. holding BQL),
avoiding potential race conditions with machines that might change the
FDT during runtime (e.g. PowerPC 'pseries' machine).

Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
Cc: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hmp-commands.hx              | 15 +++++++++++++++
 include/sysemu/device_tree.h |  1 +
 monitor/misc.c               |  1 +
 qapi/machine.json            | 18 ++++++++++++++++++
 softmmu/device_tree.c        | 31 +++++++++++++++++++++++++++++++
 5 files changed, 66 insertions(+)

diff --git a/hmp-commands.hx b/hmp-commands.hx
index 182e639d14..9a3e57504f 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -1800,3 +1800,18 @@ ERST
                       "\n\t\t\t\t\t limit on a specified virtual cpu",
         .cmd        = hmp_cancel_vcpu_dirty_limit,
     },
+
+#if defined(CONFIG_FDT)
+SRST
+``dumpdtb`` *filename*
+  Save the FDT in the 'filename' file to be decoded using dtc.
+  Requires 'libfdt' support.
+ERST
+    {
+        .name       = "dumpdtb",
+        .args_type  = "filename:F",
+        .params     = "filename",
+        .help       = "save the FDT in the 'filename' file to be decoded using dtc",
+        .cmd        = hmp_dumpdtb,
+    },
+#endif
diff --git a/include/sysemu/device_tree.h b/include/sysemu/device_tree.h
index ef060a9759..e7c5441f56 100644
--- a/include/sysemu/device_tree.h
+++ b/include/sysemu/device_tree.h
@@ -136,6 +136,7 @@ int qemu_fdt_add_path(void *fdt, const char *path);
     } while (0)
 
 void qemu_fdt_dumpdtb(void *fdt, int size);
+void hmp_dumpdtb(Monitor *mon, const QDict *qdict);
 
 /**
  * qemu_fdt_setprop_sized_cells_from_array:
diff --git a/monitor/misc.c b/monitor/misc.c
index 3d2312ba8d..e7dd63030b 100644
--- a/monitor/misc.c
+++ b/monitor/misc.c
@@ -49,6 +49,7 @@
 #include "sysemu/blockdev.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/tpm.h"
+#include "sysemu/device_tree.h"
 #include "qapi/qmp/qdict.h"
 #include "qapi/qmp/qerror.h"
 #include "qapi/qmp/qstring.h"
diff --git a/qapi/machine.json b/qapi/machine.json
index 6afd1936b0..f968a5d343 100644
--- a/qapi/machine.json
+++ b/qapi/machine.json
@@ -1664,3 +1664,21 @@
      '*size': 'size',
      '*max-size': 'size',
      '*slots': 'uint64' } }
+
+##
+# @dumpdtb:
+#
+# Save the FDT in dtb format. Requires 'libfdt' support.
+#
+# @filename: name of the FDT file to be created
+#
+# Since: 7.2
+#
+# Example:
+#   {"execute": "dumpdtb"}
+#    "arguments": { "filename": "/tmp/fdt.dtb" } }
+#
+##
+{ 'command': 'dumpdtb',
+  'data': { 'filename': 'str' },
+  'if': 'CONFIG_FDT' }
diff --git a/softmmu/device_tree.c b/softmmu/device_tree.c
index 6ca3fad285..cdd41b6de6 100644
--- a/softmmu/device_tree.c
+++ b/softmmu/device_tree.c
@@ -26,6 +26,9 @@
 #include "hw/loader.h"
 #include "hw/boards.h"
 #include "qemu/config-file.h"
+#include "qapi/qapi-commands-machine.h"
+#include "qapi/qmp/qdict.h"
+#include "monitor/hmp.h"
 
 #include <libfdt.h>
 
@@ -643,3 +646,31 @@ out:
     g_free(propcells);
     return ret;
 }
+
+void qmp_dumpdtb(const char *filename, Error **errp)
+{
+    g_autoptr(GError) err = NULL;
+    int size;
+
+    if (!current_machine->fdt) {
+        error_setg(errp, "Unable to find the machine FDT");
+        return;
+    }
+
+    size = fdt_totalsize(current_machine->fdt);
+
+    if (!g_file_set_contents(filename, current_machine->fdt, size, &err)) {
+        error_setg(errp, "Error saving FDT to file %s: %s",
+                   filename, err->message);
+    }
+}
+
+void hmp_dumpdtb(Monitor *mon, const QDict *qdict)
+{
+    const char *filename = qdict_get_str(qdict, "filename");
+    Error *local_err = NULL;
+
+    qmp_dumpdtb(filename, &local_err);
+
+    hmp_handle_error(mon, local_err);
+}
-- 
2.37.2

Re: [PATCH v5 06/14] hw/ppc: set machine->fdt in sam460ex_load_device_tree()

[BALATON Zoltan]

On Sat, 3 Sep 2022, Daniel Henrique Barboza wrote:
> This will enable support for 'dumpdtb' QMP/HMP command for the sam460ex
> machine.
>
> Cc: BALATON Zoltan <balaton@eik.bme.hu>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
> hw/ppc/sam460ex.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/sam460ex.c b/hw/ppc/sam460ex.c
> index 850bb3b817..fa6f125fda 100644
> --- a/hw/ppc/sam460ex.c
> +++ b/hw/ppc/sam460ex.c
> @@ -137,6 +137,7 @@ static int sam460ex_load_device_tree(hwaddr addr,
>                                      hwaddr initrd_size,
>                                      const char *kernel_cmdline)
> {
> +    MachineState *machine = MACHINE(qdev_get_machine());

Sorry for not noticing this earlier but this is ugly, I think you could 
just change the prototype of this function to take MachineState *machine 
instead of the ramsize and kernel_cmdline params which then can also be 
get from machine so they are not needed as separate params any more.

>     uint32_t mem_reg_property[] = { 0, 0, cpu_to_be32(ramsize) };
>     char *filename;
>     int fdt_size;
> @@ -208,7 +209,9 @@ static int sam460ex_load_device_tree(hwaddr addr,
>                               EBC_FREQ);
>
>     rom_add_blob_fixed(BINARY_DEVICE_TREE_FILE, fdt, fdt_size, addr);
> -    g_free(fdt);
> +
> +    /* Set machine->fdt for 'dumpdtb' QMP/HMP command */

You've changed this and a few other places to the short comment but left 
the long version in pegasos2 and other machines. Could you change all of 
them to make it more consistent and less lines altogether?

Regards,
BALATON Zoltan

> +    machine->fdt = fdt;
>
>     return fdt_size;
> }
>