[PATCH 2/6] hw/ppc: Trigger Fadump boot if fadump is registered

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

According to PAPR:

    R1–7.3.30–3. When the platform receives an ibm,os-term RTAS call, or
    on a system reset without an ibm,nmi-interlock RTAS call, if the
    platform has a dump structure registered through the
    ibm,configure-kernel-dump call, the platform must process each
    registered kernel dump section as required and, when available,
    present the dump structure information to the operating system
    through the “ibm,kernel-dump” property, updated with status for each
    dump section, until the dump has been invalidated through the
    ibm,configure-kernel-dump RTAS call.

If Fadump has been registered, trigger an Fadump boot (memory preserving
boot), if QEMU recieves a 'ibm,os-term' rtas call.

Implementing the fadump boot as:
    * pause all vcpus (will save registers later)
    * preserve memory regions specified by fadump
    * do a memory preserving reboot (GUEST_RESET in QEMU doesn't clear
      the memory)

Memory regions registered by fadump will be handled in a later patch.

Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
---
 hw/ppc/spapr_rtas.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
index eebdf13b1552..01c82375f03d 100644
--- a/hw/ppc/spapr_rtas.c
+++ b/hw/ppc/spapr_rtas.c
@@ -342,6 +342,43 @@ static void rtas_ibm_set_system_parameter(PowerPCCPU *cpu,
 }
 
 struct fadump_metadata fadump_metadata;
+bool is_next_boot_fadump;
+
+static void trigger_fadump_boot(target_ulong spapr_retcode)
+{
+    /*
+     * In PowerNV, SBE stops all clocks for cores, do similar to it
+     * QEMU's nearest equivalent is 'pause_all_vcpus'
+     * See 'stopClocksS0' in SBE source code for more info on SBE part
+     */
+    pause_all_vcpus();
+
+    if (true /* TODO: Preserve memory registered for fadump */) {
+        /* Failed to preserve the registered memory regions */
+        rtas_st(spapr_retcode, 0, RTAS_OUT_HW_ERROR);
+
+        /* Cause a reboot */
+        qemu_system_guest_panicked(NULL);
+        return;
+    }
+
+    /* Mark next boot as fadump boot */
+    is_next_boot_fadump = true;
+
+    /* Reset fadump_registered for next boot */
+    fadump_metadata.fadump_registered = false;
+    fadump_metadata.fadump_dump_active = true;
+
+    /* Then do a guest reset */
+    /*
+     * Requirement:
+     * This guest reset should not clear the memory (which is
+     * the case when this is merged)
+     */
+    qemu_system_reset_request(SHUTDOWN_CAUSE_GUEST_RESET);
+
+    rtas_st(spapr_retcode, 0, RTAS_OUT_SUCCESS);
+}
 
 /* Papr Section 7.4.9 ibm,configure-kernel-dump RTAS call */
 static __attribute((unused)) void rtas_configure_kernel_dump(PowerPCCPU *cpu,
@@ -449,6 +486,11 @@ static void rtas_ibm_os_term(PowerPCCPU *cpu,
     target_ulong msgaddr = rtas_ld(args, 0);
     char msg[512];
 
+    if (fadump_metadata.fadump_registered) {
+        /* If fadump boot works, control won't come back here */
+        return trigger_fadump_boot(rets);
+    }
+
     cpu_physical_memory_read(msgaddr, msg, sizeof(msg) - 1);
     msg[sizeof(msg) - 1] = 0;
 
-- 
2.48.1