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| author | Niklas Schnelle <schnelle@linux.ibm.com> | 2021-07-08 14:55:42 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2021-07-27 09:39:19 +0200 |
| commit | 3322ba0d7bea1e24ae464418626f6a15b69533ab (patch) | |
| tree | 36818fc097003229c99cb556d613dc949bdb29d0 /arch/s390/kernel/early.c | |
| parent | 196e3c6ad1ccea7552b796461d1666bfd9a76b2b (diff) | |
| download | linux-3322ba0d7bea1e24ae464418626f6a15b69533ab.tar.gz linux-3322ba0d7bea1e24ae464418626f6a15b69533ab.tar.bz2 linux-3322ba0d7bea1e24ae464418626f6a15b69533ab.zip | |
s390: make PCI mio support a machine flag
Kernel support for the newer PCI mio instructions can be toggled off
with the pci=nomio command line option which needs to integrate with
common code PCI option parsing. However this option then toggles static
branches which can't be toggled yet in an early_param() call.
Thus commit 9964f396f1d0 ("s390: fix setting of mio addressing control")
moved toggling the static branches to the PCI init routine.
With this setup however we can't check for mio support outside the PCI
code during early boot, i.e. before switching the static branches, which
we need to be able to export this as an ELF HWCAP.
Improve on this by turning mio availability into a machine flag that
gets initially set based on CONFIG_PCI and the facility bit and gets
toggled off if pci=nomio is found during PCI option parsing allowing
simple access to this machine flag after early init.
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel/early.c')
| -rw-r--r-- | arch/s390/kernel/early.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c index fb84e3fc1686..9857cb046726 100644 --- a/arch/s390/kernel/early.c +++ b/arch/s390/kernel/early.c @@ -236,6 +236,10 @@ static __init void detect_machine_facilities(void) clock_comparator_max = -1ULL >> 1; __ctl_set_bit(0, 53); } + if (IS_ENABLED(CONFIG_PCI) && test_facility(153)) { + S390_lowcore.machine_flags |= MACHINE_FLAG_PCI_MIO; + /* the control bit is set during PCI initialization */ + } } static inline void save_vector_registers(void) |