During Fadump in Qemu VM, when maxcpus value is set to more than current
cpus, following failure is observed.
[ 0.045806] [ T1] rtas fadump: Dump taken by platform is
incomplete (0)
This is because the CPU_STATE_DATA is allocated for maxcpus, while the
data is only filled for current cpus. As per current implementation
of Fadump, dumped_bytes and source_len for a region have to match,
Which is failing for qemu's case, Even tough the dumped bytes are
reported correctly for only the current cpus. After this /proc/vmcore
generatition also fails.
Allowing dumped_bytes to be lesser than or equal to allocated length, for
CPU_STATE_DATA Fadump region.
Reported-by: Anushree Mathur <[email protected]>
Closes:
https://lore.kernel.org/all/[email protected]/T/#u
Signed-off-by: Shivang Upadhyay <[email protected]>
---
Changelog:
v4:
removed extra blank line.
v3: https://lore.kernel.org/all/[email protected]/
removed extra variable.
v2: https://lore.kernel.org/all/[email protected]/
Only allowing lesser size for CPU_STATE_DATE Fadump region.
v1:
https://lore.kernel.org/qemu-devel/[email protected]/
---
arch/powerpc/platforms/pseries/rtas-fadump.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c
b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 3bb4ac2ab6cc..838e97c24308 100644
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -459,6 +459,8 @@ static int __init rtas_fadump_process(struct fw_dump
*fadump_conf)
/* Check if the dump data is valid. */
for (int i = 0; i < be16_to_cpu(fdm_active->header.dump_num_sections);
i++) {
int type = be16_to_cpu(fdm_active->rgn[i].source_data_type);
+ uint64_t bytes_dumped =
be64_to_cpu(fdm_active->rgn[i].bytes_dumped);
+ uint64_t source_len =
be64_to_cpu(fdm_active->rgn[i].source_len);
int rc = 0;
switch (type) {
@@ -469,10 +471,20 @@ static int __init rtas_fadump_process(struct fw_dump
*fadump_conf)
pr_err("Dump taken by platform is not valid
(%d)\n", i);
rc = -EINVAL;
}
- if (fdm_active->rgn[i].bytes_dumped !=
fdm_active->rgn[i].source_len) {
+
+ /*
+ * Make sure that dump is collected for entire region.
+ * CPU_STATE_DATA region is allowed to dump less than
allocated space.
+ */
+ if (!(bytes_dumped == source_len ||
+ (type == RTAS_FADUMP_CPU_STATE_DATA && bytes_dumped <=
source_len))) {
+
pr_err("Dump taken by platform is incomplete
(%d)\n", i);
+ pr_debug("type -> %d, bytes_dumped -> %llx,
source_len -> %llx\n",
+ type, bytes_dumped, source_len);
rc = -EINVAL;
}
+
if (rc) {
pr_warn("Region type: %u src addr: 0x%llx dest
addr: 0x%llx\n",
be16_to_cpu(fdm_active->rgn[i].source_data_type),
@@ -482,7 +494,7 @@ static int __init rtas_fadump_process(struct fw_dump
*fadump_conf)
}
break;
case RTAS_FADUMP_PARAM_AREA:
- if (fdm_active->rgn[i].bytes_dumped !=
fdm_active->rgn[i].source_len ||
+ if (bytes_dumped != source_len ||
fdm_active->rgn[i].error_flags != 0) {
pr_warn("Failed to process additional
parameters! Proceeding anyway..\n");
fadump_conf->param_area = 0;
--
2.54.0
