linux.git/arch/s390/include/asm/processor.h, branch v6.13

s390/mm/fault: Handle guest-related program interrupts in KVM

2024-10-29T10:49:18+00:00

Any program interrupt that happens in the host during the execution of
a KVM guest will now short circuit the fault handler and return to KVM
immediately. Guest fault handling (including pfault) will happen
entirely inside KVM.

When sie64a() returns zero, current->thread.gmap_int_code will contain
the program interrupt number that caused the exit, or zero if the exit
was not caused by a host program interrupt.

KVM will now take care of handling all guest faults in vcpu_post_run().

Since gmap faults will not be visible by the rest of the kernel, remove
GMAP_FAULT, the linux fault handlers for secure execution faults, the
exception table entries for the sie instruction, the nop padding after
the sie instruction, and all other references to guest faults from the
s390 code.

Signed-off-by: Claudio Imbrenda 
Co-developed-by: Heiko Carstens 
Link: https://lore.kernel.org/r/20241022120601.167009-6-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens

s390/smp: Add cpu capacities

2024-08-29T20:56:35+00:00

Linux scheduler allows architectures to assign capacity values to
individual CPUs. This hints scheduler the performance difference between
CPUs and allows more efficient task distribution them. Implement
helper methods to set and get CPU capacities for s390. This is
particularly helpful in vertical polarization configurations of LPARs.
On vertical polarization an LPARs CPUs can get different polarization
values depending on the CEC configuration. CPUs with different
polarization values can perform different from each other, using CPU
capacities this can be reflected to linux scheduler.

Acked-by: Vasily Gorbik 
Signed-off-by: Mete Durlu 
Signed-off-by: Vasily Gorbik

s390/entry: Move SIE indicator flag to thread info

2024-07-23T14:02:31+00:00

CIF_SIE indicates if a thread is running in SIE context. This is the
state of a thread and not the CPU. Therefore move this indicator to
thread info.

Signed-off-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik

s390/nospec: Push down alternative handling

2024-07-23T14:02:31+00:00

The nospec implementation is deeply integrated into the alternatives
code: only for nospec an alternative facility list is implemented and
used by the alternative code, while it is modified by nospec specific
needs.

Push down the nospec alternative handling into the nospec by
introducing a new alternative type and a specific nospec callback to
decide if alternatives should be applied.

Also introduce a new global nobp variable which together with facility
82 can be used to decide if nobp is enabled or not.

Acked-by: Alexander Gordeev 
Tested-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390/alternatives: Rework to allow for callbacks

2024-07-23T14:02:31+00:00

Rework alternatives to allow for callbacks. With this every
alternative entry has additional data encoded:

- When (aka context) an alternative is supposed to be applied

- The type of an alternative, which allows for type specific handling
  and callbacks

- Extra type specific payload (patch information), which can be passed
  to callbacks in order to decide if an alternative should be applied
  or not

With this only the "late" context is implemented, which means there is
no change to the previous behaviour. All code is just converted to the
more generic new infrastructure.

Reviewed-by: Alexander Gordeev 
Tested-by: Sven Schnelle 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik

s390: Move CIF flags to struct pcpu

2024-07-23T14:02:31+00:00

To allow testing flags for offline CPUs, move the CIF flags
to struct pcpu. To avoid having to calculate the array index
for each access, add a pointer to the pcpu member for the current
cpu to lowcore.

Reviewed-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik

s390: Replace S390_lowcore by get_lowcore()

2024-06-18T15:01:33+00:00

Replace all S390_lowcore usages in arch/s390/ by get_lowcore().

Acked-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik

s390: Mark psw in __load_psw_mask() as __unitialized

2024-05-14T11:37:08+00:00

Without __unitialized, the following code is generated when
INIT_STACK_ALL_ZERO is enabled:

86: d7 0f f0 a0 f0 a0     xc      160(16,%r15), 160(%r15)
8c: e3 40 f0 a0 00 24     stg     %r4, 160(%r15)
92: c0 10 00 00 00 08     larl    %r1, 0xa2
98: e3 10 f0 a8 00 24     stg     %r1, 168(%r15)
9e: b2 b2 f0 a0           lpswe   160(%r15)

The xc is not adding any security because psw is fully initialized
with the following instructions. Add __unitialized to the psw
definitiation to avoid the superfluous clearing of psw.

Reviewed-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Alexander Gordeev

s390/idle: Rewrite psw_idle() in C

2024-05-14T11:37:07+00:00

To ease maintenance and further enhancements, convert
the psw_idle() function to C.

Reviewed-by: Heiko Carstens 
Signed-off-by: Sven Schnelle 
Signed-off-by: Alexander Gordeev

s390/stackstrace: Detect vdso stack frames

2024-05-14T11:37:07+00:00

Clear the backchain of the extra stack frame added by the vdso user wrapper
code. This allows the user stack walker to detect and skip the non-standard
stack frame. Without this an incorrect instruction pointer would be added
to stack traces, and stack frame walking would be continued with a more or
less random back chain.

Fixes: aa44433ac4ee ("s390: add USER_STACKTRACE support")
Reviewed-by: Jens Remus 
Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev