| Message ID | 20230601070202.152094-5-nrb@linux.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | s390x: Add support for running guests without MSO/MSL | expand |
On 6/1/23 09:02, Nico Boehr wrote: > When we're handling a pgm int in SIE, we want to return to the SIE > cleanup after handling the exception. That's why we set pgm_old_psw to > the sie_exit label in fixup_pgm_int. > > On nullifing pgm ints, fixup_pgm_int will also forward the old PSW such > that we don't cause an pgm int again. > > However, when we want to return to the sie_exit label, this is not > needed (since we've manually set pgm_old_psw). Instead, forwarding the > PSW might cause us to skip an instruction or end up in the middle of an > instruction. > > So, let's just skip the rest of the fixup in case we're inside SIE. > > Note that we're intentionally not fixing up the PSW in the guest; that's > best left to the test at hand by registering their own psw fixup. > > Signed-off-by: Nico Boehr <nrb@linux.ibm.com> > --- > lib/s390x/interrupt.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c > index d97b5a3a7e97..3f07068877ee 100644 > --- a/lib/s390x/interrupt.c > +++ b/lib/s390x/interrupt.c > @@ -145,6 +145,7 @@ static void fixup_pgm_int(struct stack_frame_int *stack) > if (lowcore.pgm_old_psw.addr >= (uint64_t)&sie_entry && > lowcore.pgm_old_psw.addr <= (uint64_t)&sie_exit) { > lowcore.pgm_old_psw.addr = (uint64_t)&sie_exit; > + return; > } > > switch (lowcore.pgm_int_code) { Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
On Thu, 1 Jun 2023 09:02:00 +0200 Nico Boehr <nrb@linux.ibm.com> wrote: > When we're handling a pgm int in SIE, we want to return to the SIE > cleanup after handling the exception. That's why we set pgm_old_psw to > the sie_exit label in fixup_pgm_int. > > On nullifing pgm ints, fixup_pgm_int will also forward the old PSW such > that we don't cause an pgm int again. > > However, when we want to return to the sie_exit label, this is not > needed (since we've manually set pgm_old_psw). Instead, forwarding the > PSW might cause us to skip an instruction or end up in the middle of an > instruction. > > So, let's just skip the rest of the fixup in case we're inside SIE. > > Note that we're intentionally not fixing up the PSW in the guest; that's > best left to the test at hand by registering their own psw fixup. > > Signed-off-by: Nico Boehr <nrb@linux.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> > --- > lib/s390x/interrupt.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c > index d97b5a3a7e97..3f07068877ee 100644 > --- a/lib/s390x/interrupt.c > +++ b/lib/s390x/interrupt.c > @@ -145,6 +145,7 @@ static void fixup_pgm_int(struct stack_frame_int *stack) > if (lowcore.pgm_old_psw.addr >= (uint64_t)&sie_entry && > lowcore.pgm_old_psw.addr <= (uint64_t)&sie_exit) { > lowcore.pgm_old_psw.addr = (uint64_t)&sie_exit; > + return; > } > > switch (lowcore.pgm_int_code) {
diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c index d97b5a3a7e97..3f07068877ee 100644 --- a/lib/s390x/interrupt.c +++ b/lib/s390x/interrupt.c @@ -145,6 +145,7 @@ static void fixup_pgm_int(struct stack_frame_int *stack) if (lowcore.pgm_old_psw.addr >= (uint64_t)&sie_entry && lowcore.pgm_old_psw.addr <= (uint64_t)&sie_exit) { lowcore.pgm_old_psw.addr = (uint64_t)&sie_exit; + return; } switch (lowcore.pgm_int_code) {
When we're handling a pgm int in SIE, we want to return to the SIE cleanup after handling the exception. That's why we set pgm_old_psw to the sie_exit label in fixup_pgm_int. On nullifing pgm ints, fixup_pgm_int will also forward the old PSW such that we don't cause an pgm int again. However, when we want to return to the sie_exit label, this is not needed (since we've manually set pgm_old_psw). Instead, forwarding the PSW might cause us to skip an instruction or end up in the middle of an instruction. So, let's just skip the rest of the fixup in case we're inside SIE. Note that we're intentionally not fixing up the PSW in the guest; that's best left to the test at hand by registering their own psw fixup. Signed-off-by: Nico Boehr <nrb@linux.ibm.com> --- lib/s390x/interrupt.c | 1 + 1 file changed, 1 insertion(+)