[v3,6/8] hw/ppc: Pass dump-sizes property for fadump in device tree

Commit Message

Aditya Gupta March 15, 2025, 6:46 a.m. UTC

Platform (ie. QEMU) is expected to pass few device tree properties for
details for fadump:

  * "ibm,configure-kernel-dump-sizes": Space required to store dump data
    for firmware provided dump sections (ie. CPU & HPTE regions)
  * "ibm,configure-kernel-dump-version": Versions of fadump supported

Pass the above device tree nodes so that kernel can reserve sufficient
space for preserving the CPU state data

Note: As of this patch, the "kernel-dump" device tree entry is still not
added for the second boot, so after crash, the second kernel will boot
assuming fadump dump is "NOT" active, and try to register for fadump,
but since we already have fadump registered in QEMU internal state, the
register rtas call will fail with: "DUMP ACTIVE"

Signed-off-by: Aditya Gupta <[e-mail]>
---
 hw/ppc/spapr.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 57 insertions(+)

Patch

diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
index a415e51d077a..3cbc6a7409b7 100644
--- a/hw/ppc/spapr.c
+++ b/hw/ppc/spapr.c
@@ -900,6 +900,61 @@  static int spapr_dt_rng(void *fdt)
     return ret ? -1 : 0;
 }
 
+static void spapr_dt_rtas_fadump(SpaprMachineState *spapr, void *fdt, int rtas)
+{
+    MachineState *ms = MACHINE(spapr);
+    MachineClass *mc = MACHINE_GET_CLASS(ms);
+
+    uint32_t max_possible_cpus = mc->possible_cpu_arch_ids(ms)->len;
+    uint64_t fadump_cpu_state_size = 0;
+    uint16_t fadump_versions[2] = {
+        FADUMP_VERSION /* min supported version */,
+        FADUMP_VERSION /* max supported version */
+    };
+    uint32_t fadump_rgn_sizes[2][3] = {
+        {
+            cpu_to_be32(FADUMP_CPU_STATE_DATA),
+            0, 0 /* Calculated later */
+        },
+        {
+            cpu_to_be32(FADUMP_HPTE_REGION),
+            0, 0 /* HPTE region not implemented */
+        }
+    };
+
+    /*
+     * CPU State Data contains multiple fields such as header, num_cpus and
+     * register entries
+     *
+     * Calculate the maximum CPU State Data size, according to maximum
+     * possible CPUs the QEMU VM can have
+     *
+     * This calculation must match the 'cpu_state_len' calculation done in
+     * 'populate_cpu_state_data' in spapr_fadump.c
+     */
+    fadump_cpu_state_size += sizeof(struct FadumpRegSaveAreaHeader);
+    fadump_cpu_state_size += 0xc;                      /* padding as in PAPR */
+    fadump_cpu_state_size += sizeof(__be32);           /* num_cpus */
+    fadump_cpu_state_size += max_possible_cpus   *     /* reg entries */
+                             FADUMP_NUM_PER_CPU_REGS *
+                             sizeof(struct FadumpRegEntry);
+
+    /* Set maximum size for CPU state data region */
+    assert(fadump_rgn_sizes[0][0] == cpu_to_be32(FADUMP_CPU_STATE_DATA));
+
+    /* Upper 32 bits of size, usually 0 */
+    fadump_rgn_sizes[0][1] = cpu_to_be32(fadump_cpu_state_size >> 32);
+
+    /* Lower 32 bits of size */
+    fadump_rgn_sizes[0][2] = cpu_to_be32(fadump_cpu_state_size & 0xffffffff);
+
+    /* Add device tree properties required from platform for fadump */
+    _FDT((fdt_setprop(fdt, rtas, "ibm,configure-kernel-dump-version",
+                    fadump_versions, sizeof(fadump_versions))));
+    _FDT((fdt_setprop(fdt, rtas, "ibm,configure-kernel-dump-sizes",
+                    fadump_rgn_sizes, sizeof(fadump_rgn_sizes))));
+}
+
 static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
 {
     MachineState *ms = MACHINE(spapr);
@@ -1012,6 +1067,8 @@  static void spapr_dt_rtas(SpaprMachineState *spapr, void *fdt)
     _FDT(fdt_setprop(fdt, rtas, "ibm,lrdr-capacity",
                      lrdr_capacity, sizeof(lrdr_capacity)));
 
+    spapr_dt_rtas_fadump(spapr, fdt, rtas);
+
     spapr_dt_rtas_tokens(fdt, rtas);
 }