[PATCH v4 22/25] powernv/fadump: Warn before processing partial crashdump

[Hari Bathini]

If not all kernel boot memory regions are registered for MPIPL before
system crashes, try processing the partial crashdump but warn the user
before proceeding.

Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
---
 arch/powerpc/platforms/powernv/opal-fadump.c |   21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/arch/powerpc/platforms/powernv/opal-fadump.c 
b/arch/powerpc/platforms/powernv/opal-fadump.c
index b55f25c..3ef212d 100644
--- a/arch/powerpc/platforms/powernv/opal-fadump.c
+++ b/arch/powerpc/platforms/powernv/opal-fadump.c
@@ -136,6 +136,27 @@ static void opal_fadump_get_config(struct fw_dump 
*fadump_conf,
                last_end = base + size;
        }
 
+       /*
+        * Rarely, but it can so happen that system crashes before all
+        * boot memory regions are registered for MPIPL. In such
+        * cases, warn that the vmcore may not be accurate and proceed
+        * anyway as that is the best bet considering free pages, cache
+        * pages, user pages, etc are usually filtered out.
+        *
+        * Hope the memory that could not be preserved only has pages
+        * that are usually filtered out while saving the vmcore.
+        */
+       if (fdm->region_cnt < fdm->registered_regions) {
+               pr_warn("The crashdump may not be accurate as the below boot 
memory regions could not be preserved:\n");
+               i = fdm->registered_regions;
+               while (i < fdm->region_cnt) {
+                       pr_warn("\t%d. base: 0x%llx, size: 0x%llx\n",
+                               (i + 1), fdm->rgn[i].src,
+                               fdm->rgn[i].size);
+                       i++;
+               }
+       }
+
        fadump_conf->boot_mem_top = (fadump_conf->boot_memory_size + hole_size);
        fadump_conf->boot_mem_regs_cnt = fdm->region_cnt;
        opal_fadump_update_config(fadump_conf, fdm);