On Fri, 23 Jun 2023 03:25:06 -0400
Narayana Murty N <nnmli...@linux.ibm.com> wrote:
> Currently on PPC64 qemu always dumps the guest memory in
> Big Endian (BE) format even though the guest running in Little Endian
> (LE) mode. So crash tool fails to load the dump as illustrated below:
>
> Log :
> $ virsh dump DOMAIN --memory-only dump.file
>
> Domain 'DOMAIN' dumped to dump.file
>
> $ crash vmlinux dump.file
>
> <snip>
> crash 8.0.2-1.el9
>
> WARNING: endian mismatch:
> crash utility: little-endian
> dump.file: big-endian
>
> WARNING: machine type mismatch:
> crash utility: PPC64
> dump.file: (unknown)
>
> crash: dump.file: not a supported file format
> <snip>
>
> This happens because cpu_get_dump_info() passes cpu->env->has_hv_mode
> to function ppc_interrupts_little_endian(), the cpu->env->has_hv_mode
> always set for powerNV even though the guest is not running in hv mode.
> The hv mode should be taken from msr_mask MSR_HVB bit
> (cpu->env.msr_mask & MSR_HVB). This patch fixes the issue by passing
> MSR_HVB value to ppc_interrupts_little_endian() in order to determine
> the guest endianness.
>
> The crash tool also expects guest kernel endianness should match the
> endianness of the dump.
>
> The patch was tested on POWER9 box booted with Linux as host in
> following cases:
>
> Host-Endianess Qemu-Target-Machine Qemu-Generated-Guest
> Memory-Dump-Format
> BE powernv(OPAL/PowerNV) LE
> BE powernv(OPAL/PowerNV) BE
> LE powernv(OPAL/PowerNV) LE
> LE powernv(OPAL/PowerNV) BE
> LE pseries(OPAL/PowerNV/pSeries) KVMHV LE
> LE pseries TCG LE
>
> Fixes: 5609400a4228 ("target/ppc: Set the correct endianness for powernv
> memory
> dumps")
> Signed-off-by: Narayana Murty N <nnmli...@linux.ibm.com>
> ---
Thanks !
Reviewed-by: Greg Kurz <gr...@kaod.org>
> Changes since V3:
> commit message modified as per feedback from Greg Kurz, Cédric Le
> Goater and Nicholas Piggin.
> Changes since V2:
> commit message modified as per feedback from Nicholas Piggin.
> Changes since V1:
> https://lore.kernel.org/qemu-devel/20230420145055.10196-1-nnmli...@linux.ibm.com/
> The approach to solve the issue was changed based on feedback from
> Fabiano Rosas on patch V1.
> ---
> target/ppc/arch_dump.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/ppc/arch_dump.c b/target/ppc/arch_dump.c
> index f58e6359d5..a8315659d9 100644
> --- a/target/ppc/arch_dump.c
> +++ b/target/ppc/arch_dump.c
> @@ -237,7 +237,7 @@ int cpu_get_dump_info(ArchDumpInfo *info,
> info->d_machine = PPC_ELF_MACHINE;
> info->d_class = ELFCLASS;
>
> - if (ppc_interrupts_little_endian(cpu, cpu->env.has_hv_mode)) {
> + if (ppc_interrupts_little_endian(cpu, !!(cpu->env.msr_mask & MSR_HVB))) {
> info->d_endian = ELFDATA2LSB;
> } else {
> info->d_endian = ELFDATA2MSB;
--
Greg
