On Tue, 2017-11-28 at 17:26 -0200, Daniel Henrique Barboza wrote:
>
> On 11/28/2017 03:43 PM, Laurent Vivier wrote:
> > Migration of pseries is broken with TCG because
> > QEMU tries to restore KVM MMU state unconditionally.
> >
> > The result is a SIGSEGV in kvm_vm_ioctl():
> >
> > #0 kvm_vm_ioctl (s=0x0, type=-2146390353)
> > at qemu/accel/kvm/kvm-all.c:2032
> > #1 0x00000001003e3e2c in kvmppc_configure_v3_mmu
> > (cpu=<optimized out>,
> > radix=<optimized out>, gtse=<optimized out>,
> > proc_tbl=<optimized out>)
> > at qemu/target/ppc/kvm.c:396
> > #2 0x00000001002f8b88 in spapr_post_load (opaque=0x1019103c0,
> > version_id=<optimized out>) at qemu/hw/ppc/spapr.c:1578
> > #3 0x000000010059e4cc in vmstate_load_state (f=0x106230000,
> > vmsd=0x1009479e0 <vmstate_spapr>, opaque=0x1019103c0,
> > version_id=<optimized out>) at qemu/migration/vmstate.c:165
> > #4 0x00000001005987e0 in vmstate_load (f=<optimized out>,
> > se=<optimized out>)
> > at qemu/migration/savevm.c:748
> >
> > This patch fixes the problem by not calling the KVM function with
> > the
> > TCG mode.
> >
> > Fixes: d39c90f5f3 ("spapr: Fix migration of Radix guests")
> > Signed-off-by: Laurent Vivier <lviv...@redhat.com>
> > ---
> > v2: fix the comment to keep GDB backtrace lines starting with '#'
> >
> > hw/ppc/spapr.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 9efddeaee5..a471de6cab 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -1570,7 +1570,7 @@ static int spapr_post_load(void *opaque, int
> > version_id)
> > err = spapr_rtc_import_offset(&spapr->rtc, spapr-
> > >rtc_offset);
> > }
> >
> > - if (spapr->patb_entry) {
> > + if (kvm_enabled() && spapr->patb_entry) {
>
> As an alternative, I believe you can also do:
>
> if (!!spapr->patb_entry) {
>
> because the !! will return false if patb_entry is either undefined
> (as in
Hmmm, no. patb_entry is definately used in tcg
> TCG) or zero (as set in spapr_reallocate_hpt). This is the same logic
> used
> in spapr_patb_entry_needed too.
>
> But I am fine with what you did and it's also clearer, so
>
>
> Reviewed-by: Daniel Henrique Barboza <danie...@linux.vnet.ibm.com>
>
>
>
> > PowerPCCPU *cpu = POWERPC_CPU(first_cpu);
> > bool radix = !!(spapr->patb_entry & PATBE1_GR);
> > bool gtse = !!(cpu->env.spr[SPR_LPCR] & LPCR_GTSE);
>
>
