| Message ID | 1460710980-9995-1-git-send-email-thuth@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 15/04/16 10:03, Thomas Huth wrote: > env->xer only holds the lower bits of the XER register nowadays, the > SO, OV and CA bits are stored in separate variables (see the function > cpu_write_xer() for details). Since the migration code currently only > reads the "xer" variable, the upper bits are lost during migration. > Fix it by using cpu_read_xer() instead. > > Signed-off-by: Thomas Huth <thuth@redhat.com> This looks like the pre_save counterpart to the post_load patch I sent in January (see 6a9620e60cc1b16dba9ee9d9d8cb374e4303c072) so I'm fairly sure this is right. Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> ATB, Mark.
On 15.04.2016 12:17, Mark Cave-Ayland wrote: > On 15/04/16 10:03, Thomas Huth wrote: > >> env->xer only holds the lower bits of the XER register nowadays, the >> SO, OV and CA bits are stored in separate variables (see the function >> cpu_write_xer() for details). Since the migration code currently only >> reads the "xer" variable, the upper bits are lost during migration. >> Fix it by using cpu_read_xer() instead. >> >> Signed-off-by: Thomas Huth <thuth@redhat.com> > > This looks like the pre_save counterpart to the post_load patch I sent > in January (see 6a9620e60cc1b16dba9ee9d9d8cb374e4303c072) so I'm fairly > sure this is right. Ah, ok, that's why the load part was already right :-) Looks like the cpu_read/write_xer() functions have originally been introduced in da91a00f ("Split out SO, OV, CA fields from XER"), and this patch also used it for the load and save functions in machine.c. However, a little bit later, the functions had been changed to use VMState instead (see a90db158 - "Convert ppc cpu savevm to VMStateDescription"), and the cpu_read/write_xer() calls accidentally got dropped in this patch. So introducing them again now is really the right thing to do. > Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> Thanks! Thomas
On Fri, Apr 15, 2016 at 11:03:00AM +0200, Thomas Huth wrote: > env->xer only holds the lower bits of the XER register nowadays, the > SO, OV and CA bits are stored in separate variables (see the function > cpu_write_xer() for details). Since the migration code currently only > reads the "xer" variable, the upper bits are lost during migration. > Fix it by using cpu_read_xer() instead. > > Signed-off-by: Thomas Huth <thuth@redhat.com> > --- > In case somebody wants to test this, this problem can easily be > seen with my SPRs kvm-unit-test on KVM running on a P8 machine: > https://patchwork.ozlabs.org/patch/607981/ > > target-ppc/machine.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied to ppc-for-2.6, thanks. > > diff --git a/target-ppc/machine.c b/target-ppc/machine.c > index 692121e..46684fb 100644 > --- a/target-ppc/machine.c > +++ b/target-ppc/machine.c > @@ -136,7 +136,7 @@ static void cpu_pre_save(void *opaque) > > env->spr[SPR_LR] = env->lr; > env->spr[SPR_CTR] = env->ctr; > - env->spr[SPR_XER] = env->xer; > + env->spr[SPR_XER] = cpu_read_xer(env); > #if defined(TARGET_PPC64) > env->spr[SPR_CFAR] = env->cfar; > #endif
diff --git a/target-ppc/machine.c b/target-ppc/machine.c index 692121e..46684fb 100644 --- a/target-ppc/machine.c +++ b/target-ppc/machine.c @@ -136,7 +136,7 @@ static void cpu_pre_save(void *opaque) env->spr[SPR_LR] = env->lr; env->spr[SPR_CTR] = env->ctr; - env->spr[SPR_XER] = env->xer; + env->spr[SPR_XER] = cpu_read_xer(env); #if defined(TARGET_PPC64) env->spr[SPR_CFAR] = env->cfar; #endif
env->xer only holds the lower bits of the XER register nowadays, the SO, OV and CA bits are stored in separate variables (see the function cpu_write_xer() for details). Since the migration code currently only reads the "xer" variable, the upper bits are lost during migration. Fix it by using cpu_read_xer() instead. Signed-off-by: Thomas Huth <thuth@redhat.com> --- In case somebody wants to test this, this problem can easily be seen with my SPRs kvm-unit-test on KVM running on a P8 machine: https://patchwork.ozlabs.org/patch/607981/ target-ppc/machine.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)