KVM guests on s390 need a different page table layout than normal
processes (2kb page table + 2kb page status extensions vs 2kb page table
only). As of today this has to be enabled via the vm.allocate_pgste
sysctl.
Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header
and enable the pgste page table extensions in that case. This makes the
vm.allocate_pgste sysctl unnecessary. We enable this program header for
the s390 system emulation (qemu-system-s390x) if we build on s390
- for s390 system emulation
- the linker supports --s390-pgste (binutils >= 2.29)
- KVM is enabled
This will allow distributions to disable the global vm.allocate_pgste
sysctl, which will improve the page table allocation for non KVM
processes as only 2kb chunks are necessary.
Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com>
Cc: Alexander Graf <agraf@suse.de>
Cc: Dan Horak <dhorak@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com>
---
V1->V2:
- provide ld_has function
- use ld_has to replace some open coded variants
- check target arch and arch for s390
- check for s390x before calling the linker
V2->V3:
- fix typos
configure | 21 ++++++++++++++++++++-
1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/configure b/configure
index dd73cce..fb7e34a 100755
--- a/configure
+++ b/configure
@@ -240,6 +240,11 @@ supported_target() {
return 1
}
+
+ld_has() {
+ $ld --help 2>/dev/null | grep ".$1" >/dev/null 2>&1
+}
+
# default parameters
source_path=$(dirname "$0")
cpu=""
@@ -5043,7 +5048,7 @@ fi
# Use ASLR, no-SEH and DEP if available
if test "$mingw32" = "yes" ; then
for flag in --dynamicbase --no-seh --nxcompat; do
- if $ld --help 2>/dev/null | grep ".$flag" >/dev/null 2>/dev/null ; then
+ if ld_has $flag ; then
LDFLAGS="-Wl,$flag $LDFLAGS"
fi
done
@@ -6522,6 +6527,20 @@ if test "$target_linux_user" = "yes" -o "$target_bsd_user" = "yes" ; then
ldflags="$ldflags $textseg_ldflags"
fi
+# Newer kernels on s390 check for an S390_PGSTE program header and
+# enable the pgste page table extensions in that case. This makes
+# the vm.allocate_pgste sysctl unnecessary. We enable this program
+# header if
+# - we build on s390x
+# - we build the system emulation for s390x (qemu-system-s390x)
+# - KVM is enabled
+# - the linker supports --s390-pgste
+if test "$TARGET_ARCH" = "s390x" -a "$target_softmmu" = "yes" -a "$ARCH" = "s390x" -a "$kvm" = "yes"; then
+ if ld_has --s390-pgste ; then
+ ldflags="-Wl,--s390-pgste $ldflags"
+ fi
+fi
+
echo "LDFLAGS+=$ldflags" >> $config_target_mak
echo "QEMU_CFLAGS+=$cflags" >> $config_target_mak
--
2.7.4
On Wed, 23 Aug 2017 12:16:23 +0200 Christian Borntraeger <borntraeger@de.ibm.com> wrote: > KVM guests on s390 need a different page table layout than normal > processes (2kb page table + 2kb page status extensions vs 2kb page table > only). As of today this has to be enabled via the vm.allocate_pgste > sysctl. > > Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header > and enable the pgste page table extensions in that case. This makes the > vm.allocate_pgste sysctl unnecessary. We enable this program header for > the s390 system emulation (qemu-system-s390x) if we build on s390 > - for s390 system emulation > - the linker supports --s390-pgste (binutils >= 2.29) > - KVM is enabled > > This will allow distributions to disable the global vm.allocate_pgste > sysctl, which will improve the page table allocation for non KVM > processes as only 2kb chunks are necessary. > > Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com> > Cc: Alexander Graf <agraf@suse.de> > Cc: Dan Horak <dhorak@redhat.com> > Cc: David Hildenbrand <david@redhat.com> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> > --- > V1->V2: > - provide ld_has function > - use ld_has to replace some open coded variants > - check target arch and arch for s390 > - check for s390x before calling the linker > V2->V3: > - fix typos > configure | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) Looks sane. I guess I'll wait for some more Acks or R-bs and then queue it to s390-next.
On 23.08.2017 14:31, Cornelia Huck wrote: > On Wed, 23 Aug 2017 12:16:23 +0200 > Christian Borntraeger <borntraeger@de.ibm.com> wrote: > >> KVM guests on s390 need a different page table layout than normal >> processes (2kb page table + 2kb page status extensions vs 2kb page table >> only). As of today this has to be enabled via the vm.allocate_pgste >> sysctl. >> >> Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header >> and enable the pgste page table extensions in that case. This makes the >> vm.allocate_pgste sysctl unnecessary. We enable this program header for >> the s390 system emulation (qemu-system-s390x) if we build on s390 >> - for s390 system emulation >> - the linker supports --s390-pgste (binutils >= 2.29) >> - KVM is enabled >> >> This will allow distributions to disable the global vm.allocate_pgste >> sysctl, which will improve the page table allocation for non KVM >> processes as only 2kb chunks are necessary. >> >> Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com> >> Cc: Alexander Graf <agraf@suse.de> >> Cc: Dan Horak <dhorak@redhat.com> >> Cc: David Hildenbrand <david@redhat.com> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> >> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> >> --- >> V1->V2: >> - provide ld_has function >> - use ld_has to replace some open coded variants >> - check target arch and arch for s390 >> - check for s390x before calling the linker >> V2->V3: >> - fix typos >> configure | 21 ++++++++++++++++++++- >> 1 file changed, 20 insertions(+), 1 deletion(-) > > Looks sane. > > I guess I'll wait for some more Acks or R-bs and then queue it to > s390-next. > My r-b still holds Reviewed-by: David Hildenbrand <david@redhat.com> -- Thanks, David
On 08/23/2017 02:31 PM, Cornelia Huck wrote: > On Wed, 23 Aug 2017 12:16:23 +0200 > Christian Borntraeger <borntraeger@de.ibm.com> wrote: > >> KVM guests on s390 need a different page table layout than normal >> processes (2kb page table + 2kb page status extensions vs 2kb page table >> only). As of today this has to be enabled via the vm.allocate_pgste >> sysctl. >> >> Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header >> and enable the pgste page table extensions in that case. This makes the >> vm.allocate_pgste sysctl unnecessary. We enable this program header for >> the s390 system emulation (qemu-system-s390x) if we build on s390 >> - for s390 system emulation >> - the linker supports --s390-pgste (binutils >= 2.29) >> - KVM is enabled >> >> This will allow distributions to disable the global vm.allocate_pgste >> sysctl, which will improve the page table allocation for non KVM >> processes as only 2kb chunks are necessary. >> >> Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com> >> Cc: Alexander Graf <agraf@suse.de> >> Cc: Dan Horak <dhorak@redhat.com> >> Cc: David Hildenbrand <david@redhat.com> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> >> Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> >> --- >> V1->V2: >> - provide ld_has function >> - use ld_has to replace some open coded variants >> - check target arch and arch for s390 >> - check for s390x before calling the linker >> V2->V3: >> - fix typos >> configure | 21 ++++++++++++++++++++- >> 1 file changed, 20 insertions(+), 1 deletion(-) > > Looks sane. > > I guess I'll wait for some more Acks or R-bs and then queue it to > s390-next. Sure. Looks like I forgot to add Thomas/Davids R-bs, so please add those.
On Wed, 23 Aug 2017 12:16:23 +0200 Christian Borntraeger <borntraeger@de.ibm.com> wrote: > KVM guests on s390 need a different page table layout than normal > processes (2kb page table + 2kb page status extensions vs 2kb page table > only). As of today this has to be enabled via the vm.allocate_pgste > sysctl. > > Newer kernels (>= 4.12) on s390 check for an S390_PGSTE program header > and enable the pgste page table extensions in that case. This makes the > vm.allocate_pgste sysctl unnecessary. We enable this program header for > the s390 system emulation (qemu-system-s390x) if we build on s390 > - for s390 system emulation > - the linker supports --s390-pgste (binutils >= 2.29) > - KVM is enabled > > This will allow distributions to disable the global vm.allocate_pgste > sysctl, which will improve the page table allocation for non KVM > processes as only 2kb chunks are necessary. > > Cc: Christian Ehrhardt <christian.ehrhardt@canonical.com> > Cc: Alexander Graf <agraf@suse.de> > Cc: Dan Horak <dhorak@redhat.com> > Cc: David Hildenbrand <david@redhat.com> > Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com> > Acked-by: Janosch Frank <frankja@linux.vnet.ibm.com> > --- > V1->V2: > - provide ld_has function > - use ld_has to replace some open coded variants > - check target arch and arch for s390 > - check for s390x before calling the linker > V2->V3: > - fix typos > configure | 21 ++++++++++++++++++++- > 1 file changed, 20 insertions(+), 1 deletion(-) Thanks, applied.
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