[PATCH 6/6] hw/ppc: Enable Fadump for PSeries

[Aditya Gupta <adityag@linux.ibm.com>]

With all support in place, enable fadump by exporting the
"ibm,configure-kernel-dump" RTAS call in the device tree.

Presence of "ibm,configure-kernel-dump" tells the kernel that the
platform (QEMU) supports fadump.

Pass "fadump=on" to enable Linux to use firmware assisted dump.

Logs of a linux boot with firmware assisted dump:

    ./build/qemu-system-ppc64 -M pseries,x-vof=on --cpu power10 --smp 4 -m 4G -kernel some-vmlinux -initrd some-initrd -append "debug fadump=on crashkernel=1G" -nographic
    [    0.000000] random: crng init done
    [    0.000000] fadump: Reserved 1024MB of memory at 0x00000040000000 (System RAM: 4096MB)
    ...
    [    1.084686] rtas fadump: Registration is successful!
    ...
    # cat /sys/kernel/debug/powerpc/fadump_region
    CPU :[0x00000040000000-0x000000400013d3] 0x13d4 bytes, Dumped: 0x0
    HPTE:[0x000000400013d4-0x000000400013d3] 0x0 bytes, Dumped: 0x0
    DUMP: Src: 0x00000000000000, Dest: 0x00000040010000, Size: 0x40000000, Dumped: 0x0 bytes

    [0x000000fffff800-0x000000ffffffff]: cmdline append: ''
    # echo c > /proc/sysrq-trigger

The fadump boot after crash:

    [    0.000000] rtas fadump: Firmware-assisted dump is active.
    [    0.000000] fadump: Updated cmdline: debug fadump=on crashkernel=1G
    [    0.000000] fadump: Firmware-assisted dump is active.
    [    0.000000] fadump: Reserving 3072MB of memory at 0x00000040000000 for preserving crash data
    ....
    # file /proc/vmcore
    /proc/vmcore: ELF 64-bit LSB core file, 64-bit PowerPC or cisco 7500, OpenPOWER ELF V2 ABI, version 1 (SYSV), SVR4-style

Analysing the vmcore with crash-utility:

          KERNEL: vmlinux-6.14-rc2
        DUMPFILE: vmcore-a64dcfb451e2-nocma
            CPUS: 4
            DATE: Thu Jan  1 05:30:00 IST 1970
          UPTIME: 00:00:30
    LOAD AVERAGE: 0.74, 0.21, 0.07
           TASKS: 94
        NODENAME: buildroot
         RELEASE: 6.14.0-rc2+
         VERSION: #1 SMP Wed Feb 12 06:49:59 CST 2025
         MACHINE: ppc64le  (1000 Mhz)
          MEMORY: 4 GB
           PANIC: "Kernel panic - not syncing: sysrq triggered crash"
             PID: 270
         COMMAND: "sh"
            TASK: c000000009e7cc00  [THREAD_INFO: c000000009e7cc00]
             CPU: 3
           STATE: TASK_RUNNING (PANIC)

Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
---
 hw/ppc/spapr_rtas.c    | 6 +++++-
 include/hw/ppc/spapr.h | 3 ++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index 0aca4270aee8..bd2ed16a46e3 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -692,7 +692,7 @@ static void trigger_fadump_boot(target_ulong spapr_retcode)
 }
 
 /* Papr Section 7.4.9 ibm,configure-kernel-dump RTAS call */
-static __attribute((unused)) void rtas_configure_kernel_dump(PowerPCCPU *cpu,
+static void rtas_configure_kernel_dump(PowerPCCPU *cpu,
                                    SpaprMachineState *spapr,
                                    uint32_t token, uint32_t nargs,
                                    target_ulong args,
@@ -1109,6 +1109,10 @@ static void core_rtas_register_types(void)
     spapr_rtas_register(RTAS_IBM_NMI_INTERLOCK, "ibm,nmi-interlock",
                         rtas_ibm_nmi_interlock);
 
+    /* Register Fadump rtas call */
+    spapr_rtas_register(RTAS_CONFIGURE_KERNEL_DUMP, "ibm,configure-kernel-dump",
+                        rtas_configure_kernel_dump);
+
     qtest_set_command_cb(spapr_qtest_callback);
 }
 
diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
index fa63008e57ec..bde3bdc4b80c 100644
--- a/include/hw/ppc/spapr.h
+++ b/include/hw/ppc/spapr.h
@@ -768,8 +768,9 @@ void push_sregs_to_kvm_pr(SpaprMachineState *spapr);
 #define RTAS_IBM_SUSPEND_ME                     (RTAS_TOKEN_BASE + 0x2A)
 #define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2B)
 #define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2C)
+#define RTAS_CONFIGURE_KERNEL_DUMP              (RTAS_TOKEN_BASE + 0x2D)
 
-#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2D)
+#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2E)
 
 /* Fadump commands */
 #define FADUMP_CMD_REGISTER            1
-- 
2.48.1