This update partially reverts commit 3037a52f9846 ("s390/nmi:
do register validation as early as possible").

Storage error checks and control registers validation are left
in the assembler code, since correct ASCEs and page tables are
required to enable DAT - which is done before the C handler is
entered.

System damage, kernel instruction address and PSW MWP checks
are left in the assembler code as well, since there is no way
to proceed if one of these checks is failed.

The getcpu vdso syscall reads CPU number from the programmable
field of the TOD clock. Disregard the TOD programmable register
validity bit and load the CPU number into the TOD programmable
field unconditionally.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

The current storage errors tackling is wrong - the DAT is
enabled in assembler code before the actual storage checks
in C half are executed. In case the page tables themselves
are damaged such approach is not going to work.

With this update unrecoverable storage errors are not
passed to C code for handling, but rather the machine
is stopped right away. The only exception to this flow
is when a machine check occurred in KVM guest - in this
case the errors are reinjected by the handler.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

The machine check handler must be entered with DAT disabled
in case control registers are corrupted or a storage error
happened and we can not tell if such error corresponds to a
page table.

Both of described conditions end up in stopping all CPUs and
entering the disabled wait in C half of the handler. However,
the storage errors are still checked after the DAT is enabled
and C code is entered. In case a page table is damaged such
flow is not expected to work.

This update paves the way for moving the storage error checks
from C to assembler half. All fatal errors that can only be
handled with DAT disabled are handled in assembler half also.
As result, the C half is only entered if the DAT is secured.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

In case of the !CONFIG_KVM use "jz" instead of "jnz" when
detecting user mode and get rid of unnecessary jump as result.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Christia Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Factor out SIEEXIT macro and use it instead of cleanup_sie
routine. As a side effect %r13 and %r14 are spared.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Christia Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Pull s390 updates from Vasily Gorbik:

 - Rework inline asm to get rid of error prone "register asm"
   constructs, which are problematic especially when code
   instrumentation is enabled.

   In particular introduce and use register pair union to allocate
   even/odd register pairs. Unfortunately this breaks compatibility with
   older clang compilers and minimum clang version for s390 has been
   raised to 13.

     https://lore.kernel.org/linux-next/CAK7LNARuSmPCEy-ak0erPrPTgZdGVypBROFhtw+=3spoGoYsyw@mail.gmail.com/

 - Fix gcc 11 warnings, which triggered various minor reworks all over
   the code.

 - Add zstd kernel image compression support.

 - Rework boot CPU lowcore handling.

 - De-duplicate and move kernel memory layout setup logic earlier.

 - Few fixes in preparation for FORTIFY_SOURCE performing compile-time
   and run-time field bounds checking for mem functions.

 - Remove broken and unused power management support leftovers in s390
   drivers.

 - Disable stack-protector for decompressor and purgatory to fix
   buildroot build.

 - Fix vt220 sclp console name to match the char device name.

 - Enable HAVE_IOREMAP_PROT and add zpci_set_irq()/zpci_clear_irq() in
   zPCI code.

 - Remove some implausible WARN_ON_ONCEs and remove arch specific
   counter transaction call backs in favour of default transaction
   handling in perf code.

 - Extend/add new uevents for online/config/mode state changes of AP
   card / queue device in zcrypt.

 - Minor entry and ccwgroup code improvements.

 - Other small various fixes and improvements all over the code.

* tag 's390-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (91 commits)
  s390/dasd: use register pair instead of register asm
  s390/qdio: get rid of register asm
  s390/ioasm: use symbolic names for asm operands
  s390/ioasm: get rid of register asm
  s390/cmf: get rid of register asm
  s390/lib,string: get rid of register asm
  s390/lib,uaccess: get rid of register asm
  s390/string: get rid of register asm
  s390/cmpxchg: use register pair instead of register asm
  s390/mm,pages-states: get rid of register asm
  s390/lib,xor: get rid of register asm
  s390/timex: get rid of register asm
  s390/hypfs: use register pair instead of register asm
  s390/zcrypt: Switch to flexible array member
  s390/speculation: Use statically initialized const for instructions
  virtio/s390: get rid of open-coded kvm hypercall
  s390/pci: add zpci_set_irq()/zpci_clear_irq()
  scripts/min-tool-version.sh: Raise minimum clang version to 13.0.0 for s390
  s390/ipl: use register pair instead of register asm
  s390/mem_detect: fix tprot() program check new psw handling
  ...

The current irq entry code doesn't initialize pt_regs::flags. On exit to
user mode arch_do_signal_or_restart() tests whether PIF_SYSCALL is set,
which might yield wrong results.

Fix this by clearing pt_regs::flags in the entry.S irq handler
code.

Reported-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Fixes: 56e62a737028 ("s390: convert to generic entry")
Cc: <stable@vger.kernel.org> # 5.12
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

Introduce OUTSIDE macro that checks whether an instruction
address is inside or outside of a block of instructions.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

cleanup_sie_mcck label is called from a single location only
and thus does not need to be a subroutine. Move the labelled
code to the caller - by doing that the SIE critical section
checks appear next to each other and the SIE cleanup becomes
bit more readable.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

This helps to avoid merge conflicts later.

* fixes:
  s390/mcck: fix invalid KVM guest condition check
  s390/mcck: fix calculation of SIE critical section size

Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>