On Fri Aug 4, 2023 at 6:50 PM AEST, Pavel Dovgalyuk wrote: > BTW, there is a function qemu_register_reset_nosnapshotload that can be > used in similar cases. > Can you just use it without changing the code of the reset handler?
I didn't know that, thanks for pointing it out. I'll take a closer look at it before reposting. Thanks, Nick > > On 26.07.2023 21:35, Nicholas Piggin wrote: > > spapr_machine_reset gets a random number to populate the device-tree > > rng seed with. When loading a snapshot for record-replay, the machine > > is reset again, and that tries to consume the random event record > > again, crashing due to inconsistent record > > > > Fix this by saving the seed to populate the device tree with, and > > skipping the rng on snapshot load. > > > > Cc: Pavel Dovgalyuk <pavel.dovgal...@ispras.ru> > > Signed-off-by: Nicholas Piggin <npig...@gmail.com> > > --- > > hw/ppc/spapr.c | 12 +++++++++--- > > include/hw/ppc/spapr.h | 1 + > > 2 files changed, 10 insertions(+), 3 deletions(-) > > > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > > index 7d84244f03..ecfbdb0030 100644 > > --- a/hw/ppc/spapr.c > > +++ b/hw/ppc/spapr.c > > @@ -1022,7 +1022,6 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, > > void *fdt, bool reset) > > { > > MachineState *machine = MACHINE(spapr); > > SpaprMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine); > > - uint8_t rng_seed[32]; > > int chosen; > > > > _FDT(chosen = fdt_add_subnode(fdt, 0, "chosen")); > > @@ -1100,8 +1099,7 @@ static void spapr_dt_chosen(SpaprMachineState *spapr, > > void *fdt, bool reset) > > spapr_dt_ov5_platform_support(spapr, fdt, chosen); > > } > > > > - qemu_guest_getrandom_nofail(rng_seed, sizeof(rng_seed)); > > - _FDT(fdt_setprop(fdt, chosen, "rng-seed", rng_seed, sizeof(rng_seed))); > > + _FDT(fdt_setprop(fdt, chosen, "rng-seed", spapr->fdt_rng_seed, 32)); > > > > _FDT(spapr_dt_ovec(fdt, chosen, spapr->ov5_cas, > > "ibm,architecture-vec-5")); > > } > > @@ -1654,6 +1652,14 @@ static void spapr_machine_reset(MachineState > > *machine, ShutdownCause reason) > > void *fdt; > > int rc; > > > > + if (reason != SHUTDOWN_CAUSE_SNAPSHOT_LOAD) { > > + /* > > + * Record-replay snapshot load must not consume random, this was > > + * already replayed from initial machine reset. > > + */ > > + qemu_guest_getrandom_nofail(spapr->fdt_rng_seed, 32); > > + } > > + > > pef_kvm_reset(machine->cgs, &error_fatal); > > spapr_caps_apply(spapr); > > > > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h > > index f47e8419a5..f4bd204d86 100644 > > --- a/include/hw/ppc/spapr.h > > +++ b/include/hw/ppc/spapr.h > > @@ -204,6 +204,7 @@ struct SpaprMachineState { > > uint32_t fdt_size; > > uint32_t fdt_initial_size; > > void *fdt_blob; > > + uint8_t fdt_rng_seed[32]; > > long kernel_size; > > bool kernel_le; > > uint64_t kernel_addr;