diff options
| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-06-22 17:14:14 +0200 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-07-22 09:58:03 +0200 |
| commit | dcd2a9aaa0e0331ba0c4d7a64830788f22f26aa4 (patch) | |
| tree | 49711292e4ef4cd27bc12f326c12f7194c1b293e /arch/s390/kernel/entry.S | |
| parent | d05377c12ae2ac88e747a28ae1e23f556d549592 (diff) | |
s390/kvm: fix interrupt race with HANDLE_SIE_INTERCEPT
The HANDLE_SIE_INTERCEPT macro is used in the interrupt handlers
and the program check handler to undo a few changes done by sie64a.
Among them are guest vs host LPP, the gmap ASCE vs kernel ASCE and
the bit that indicates that SIE is currently running on the CPU.
There is a race of a voluntary SIE exit vs asynchronous interrupts.
If the CPU completed the SIE instruction and the TM instruction of
the LPP macro at the time it receives an interrupt, the interrupt
handler will run while the LPP, the ASCE and the SIE bit are still
set up for guest execution. This might result in wrong sampling data,
but it will not cause data corruption or lockups.
The critical section in sie64a needs to be enlarged to include all
instructions that undo the changes required for guest execution.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/kernel/entry.S')
| -rw-r--r-- | arch/s390/kernel/entry.S | 14 |
1 files changed, 4 insertions, 10 deletions
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index 05ea485156ee..391db6412b85 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -90,14 +90,7 @@ _PIF_WORK = (_PIF_PER_TRAP) lgr \scratch,%r9 slg \scratch,BASED(.Lsie_critical) clg \scratch,BASED(.Lsie_critical_length) - .if \reason==1 - # Some program interrupts are suppressing (e.g. protection). - # We must also check the instruction after SIE in that case. - # do_protection_exception will rewind to .Lrewind_pad - jh .+42 - .else jhe .+42 - .endif lg %r14,__SF_EMPTY(%r15) # get control block pointer LPP __SF_EMPTY+16(%r15) # set host id ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE @@ -1308,15 +1301,16 @@ ENTRY(sie64a) lg %r14,__SF_EMPTY(%r15) # get control block pointer oi __SIE_PROG0C+3(%r14),1 # we are going into SIE now tm __SIE_PROG20+3(%r14),3 # last exit... - jnz .Lsie_done + jnz .Lsie_skip tm __LC_CPU_FLAGS+7,_CIF_FPU - jo .Lsie_done # exit if fp/vx regs changed + jo .Lsie_skip # exit if fp/vx regs changed LPP __SF_EMPTY(%r15) # set guest id sie 0(%r14) -.Lsie_done: LPP __SF_EMPTY+16(%r15) # set host id +.Lsie_skip: ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE lctlg %c1,%c1,__LC_USER_ASCE # load primary asce +.Lsie_done: # some program checks are suppressing. C code (e.g. do_protection_exception) # will rewind the PSW by the ILC, which is 4 bytes in case of SIE. Other # instructions between sie64a and .Lsie_done should not cause program |