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| author | Alexander Gordeev <agordeev@linux.ibm.com> | 2022-05-23 12:38:14 +0200 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2022-06-01 12:03:16 +0200 |
| commit | 29ccaa4b35ea874ddd50518e5c2c746b9238a792 (patch) | |
| tree | 317746bcb0adf1e3bf3ff60c105644e7d21544fb /arch/s390/kernel | |
| parent | 3ae11dbcfac906a8c3a480e98660a823130dc16a (diff) | |
| download | linux-next-29ccaa4b35ea874ddd50518e5c2c746b9238a792.tar.gz | |
s390/mcck: isolate SIE instruction when setting CIF_MCCK_GUEST flag
Commit d768bd892fc8 ("s390: add options to change branch prediction
behaviour for the kernel") introduced .Lsie_exit label - supposedly
to fence off SIE instruction. However, the corresponding address
range length .Lsie_crit_mcck_length was not updated, which led to
BPON code potentionally marked with CIF_MCCK_GUEST flag.
Both .Lsie_exit and .Lsie_crit_mcck_length were removed with commit
0b0ed657fe00 ("s390: remove critical section cleanup from entry.S"),
but the issue persisted - currently BPOFF and BPENTER macros might
get wrongly considered by the machine check handler as a guest.
Fixes: d768bd892fc8 ("s390: add options to change branch prediction behaviour for the kernel")
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/entry.S | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 82faf4d0e4d7..d2a1f2f4f5b8 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -251,6 +251,10 @@ ENTRY(sie64a) BPEXIT __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST) .Lsie_entry: sie 0(%r14) +# Let the next instruction be NOP to avoid triggering a machine check +# and handling it in a guest as result of the instruction execution. + nopr 7 +.Lsie_leave: BPOFF BPENTER __SF_SIE_FLAGS(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST) .Lsie_skip: @@ -547,7 +551,7 @@ ENTRY(mcck_int_handler) jno .Lmcck_panic #if IS_ENABLED(CONFIG_KVM) OUTSIDE %r9,.Lsie_gmap,.Lsie_done,6f - OUTSIDE %r9,.Lsie_entry,.Lsie_skip,4f + OUTSIDE %r9,.Lsie_entry,.Lsie_leave,4f oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST j 5f 4: CHKSTG .Lmcck_panic |