powerpc/fadump: save CPU reg data in vmcore when PHYP terminates LPAR

An LPAR can be terminated by the POWER Hypervisor (PHYP) for various
reasons. If FADump was configured when PHYP terminates the LPAR,
platform-assisted dump is initiated to save the kernel dump. But CPU
register data would not be processed/saved in the vmcore in such case
because CPU mask is set in crash_fadump() at the time of kernel crash
and it remains unset in this case with LPAR being terminated by PHYP
abruptly.

To get around the problem, initialize cpu_mask to cpu_possible_mask
so as to ensure all possible CPUs' register data is processed for the
vmcore generated on PHYP terminated LPAR. Also, rename the crash info
member variable from online_mask to cpu_mask as it doesn't necessarily
have to be online CPU mask always.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220404182137.59231-1-hbathini@linux.ibm.com

diff --git a/arch/powerpc/include/asm/fadump-internal.h b/arch/powerpc/include/asm/fadump-internal.h
index 81bcb9abb3718fdf3cfa9898efd52b5c1656c384..27f9e11eda28cd2c9254b52e9fdafe1eac820003 100644 (file)
--- a/arch/powerpc/include/asm/fadump-internal.h
+++ b/arch/powerpc/include/asm/fadump-internal.h
@@ -50,7 +50,7 @@ struct fadump_crash_info_header {
        u64             elfcorehdr_addr;
        u32             crashing_cpu;
        struct pt_regs  regs;
-       struct cpumask  online_mask;
+       struct cpumask  cpu_mask;
 };
 
 struct fadump_memory_range {

diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
index 65562c4a0a690b7672eddacfe81c2ecda083fcd7..8343c0b142772be4cdf5a4c05e466b5aaa9f5a69 100644 (file)
--- a/arch/powerpc/kernel/fadump.c
+++ b/arch/powerpc/kernel/fadump.c
@@ -728,7 +728,7 @@ void crash_fadump(struct pt_regs *regs, const char *str)
        else
                ppc_save_regs(&fdh->regs);
 
-       fdh->online_mask = *cpu_online_mask;
+       fdh->cpu_mask = *cpu_online_mask;
 
        /*
         * If we came in via system reset, wait a while for the secondary
@@ -1164,6 +1164,11 @@ static unsigned long init_fadump_header(unsigned long addr)
        fdh->elfcorehdr_addr = addr;
        /* We will set the crashing cpu id in crash_fadump() during crash. */
        fdh->crashing_cpu = FADUMP_CPU_UNKNOWN;
+       /*
+        * When LPAR is terminated by PYHP, ensure all possible CPUs'
+        * register data is processed while exporting the vmcore.
+        */
+       fdh->cpu_mask = *cpu_possible_mask;
 
        return addr;
 }

diff --git a/arch/powerpc/platforms/pseries/rtas-fadump.c b/arch/powerpc/platforms/pseries/rtas-fadump.c
index 35f9cb602c304bb3fc595c32447a126564fa09ae..617c0f3b1f4f155900a1bc761f509df43a5344db 100644 (file)
--- a/arch/powerpc/platforms/pseries/rtas-fadump.c
+++ b/arch/powerpc/platforms/pseries/rtas-fadump.c
@@ -351,7 +351,7 @@ static int __init rtas_fadump_build_cpu_notes(struct fw_dump *fadump_conf)
                /* Lower 4 bytes of reg_value contains logical cpu id */
                cpu = (be64_to_cpu(reg_entry->reg_value) &
                       RTAS_FADUMP_CPU_ID_MASK);
-               if (fdh && !cpumask_test_cpu(cpu, &fdh->online_mask)) {
+               if (fdh && !cpumask_test_cpu(cpu, &fdh->cpu_mask)) {
                        RTAS_FADUMP_SKIP_TO_NEXT_CPU(reg_entry);
                        continue;
                }