linux-toradex.git/arch/s390/kernel/nmi.c, branch v6.7

s390: use control register bit defines

2023-09-19T11:26:57+00:00

Use control register bit defines instead of plain numbers where
possible.

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

s390/ctlreg: add struct ctlreg

2023-09-19T11:26:56+00:00

Add struct ctlreg to enforce strict type checking / usage for control
register functions.

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

s390/ctlreg: use local_ctl_load() and local_ctl_store() where possible

2023-09-19T11:26:56+00:00

Convert all single control register usages of __local_ctl_load() and
__local_ctl_store() to local_ctl_load() and local_ctl_store().

This also requires to change the type of some struct lowcore members
from __u64 to unsigned long.

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

s390/ctlreg: add local and system prefix to some functions

2023-09-19T11:26:56+00:00

Add local and system prefix to some functions to clarify they change
control register contents on either the local CPU or the on all CPUs.

This results in the following API:

Two defines which load and save multiple control registers.
The defines correlate with the following C prototypes:

void __local_ctl_load(unsigned long *, unsigned int cr_low, unsigned int cr_high);
void __local_ctl_store(unsigned long *, unsigned int cr_low, unsigned int cr_high);

Two functions which locally set or clear one bit for a specified
control register:

void local_ctl_set_bit(unsigned int cr, unsigned int bit);
void local_ctl_clear_bit(unsigned int cr, unsigned int bit);

Two functions which set or clear one bit for a specified control
register on all CPUs:

void system_ctl_set_bit(unsigned int cr, unsigned int bit);
void system_ctl_clear_bit(unsigend int cr, unsigned int bit);

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

s390/ctlreg: rename ctl_reg.h to ctlreg.h

2023-09-19T11:26:56+00:00

Rename ctl_reg.h to ctlreg.h so it matches not only ctlreg.c but also
other control register related function, union, and structure names,
which all come with a ctlreg prefix.

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

s390/mcck: cleanup user process termination path

2023-02-28T12:19:05+00:00

If a machine check interrupt hits while user process is
running __s390_handle_mcck() helper function is called
directly from the interrupt handler and terminates the
current process by calling make_task_dead() routine.

The make_task_dead() is not allowed to be called from
interrupt context which forces the machine check handler
switch to the kernel stack and enable local interrupts
first.

The __s390_handle_mcck() could also be called to service
pending work, but this time from the external interrupts
handler. It is the machine check handler that establishes
the work and schedules the external interrupt, therefore
the machine check interrupt itself should be disabled
while reading out the corresponding variable:

	local_mcck_disable();
	mcck = *this_cpu_ptr(&cpu_mcck);
	memset(this_cpu_ptr(&cpu_mcck), 0, sizeof(mcck));
	local_mcck_enable();

However, local_mcck_disable() does not have effect when
__s390_handle_mcck() is called directly form the machine
check handler, since the machine check interrupt is still
disabled. Therefore, it is not the opening bracket to the
following local_mcck_enable() function.

Simplify the user process termination flow by scheduling
the external interrupt and killing the affected process
from the interrupt context.

Assume a kernel-generated signal is always delivered and
ignore a value returned by do_send_sig_info() funciton.

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

s390/nmi: fix virtual-physical address confusion

2023-02-27T14:29:36+00:00

When a machine check is received while in SIE, it is reinjected into the
guest in some cases. The respective code needs to access the sie_block,
which is taken from the backed up R14.

Since reinjection only occurs while we are in SIE (i.e. between the
labels sie_entry and sie_leave in entry.S and thus if CIF_MCCK_GUEST is
set), the backed up R14 will always contain a physical address in
s390_backup_mcck_info.

This currently works, because virtual and physical addresses are
the same.

Add phys_to_virt() to resolve the virtual-physical confusion.

Signed-off-by: Nico Boehr 
Reviewed-by: Claudio Imbrenda 
Reviewed-by: Alexander Gordeev 
Link: https://lore.kernel.org/r/20230216121208.4390-2-nrb@linux.ibm.com
Signed-off-by: Janosch Frank 
Signed-off-by: Heiko Carstens

s390/nmi: get rid of private slab cache

2022-12-06T15:18:26+00:00

Get rid of private "nmi_save_areas" slab cache. The only reason this was
introduced years ago was that with some slab debugging options allocations
would only guarantee a minimum alignment of ARCH_KMALLOC_MINALIGN, which
was eight bytes back then. This is not sufficient for the extended machine
check save area.

However since commit 59bb47985c1d ("mm, sl[aou]b: guarantee natural
alignment for kmalloc(power-of-two)") kmalloc guarantees a power-of-two
alignment even with debugging options enabled.

Therefore the private slab cache can be removed.

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

s390/nmi: move storage error checking back to C, enter with DAT on

2022-12-06T15:18:25+00:00

Checking for storage errors in machine check entry code was done in order
to handle also storage errors on kernel page tables. However this is
extremely unlikely and some basic assumptions what works on machine check
entry are necessary anyway. In order to simplify machine check handling
delay checking for storage errors to C code.
With this also change the machine check new PSW to have DAT on, which
simplifies the entry code even further.

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

s390/nmi: print machine check interruption code before stopping system

2022-12-06T15:18:25+00:00

In case a system will be stopped because of e.g. missing validity bits
print the machine check interruption code before the system is stopped.

This is helpful, since up to now no message was printed in such a
case. Only a disabled wait PSW was loaded, which doesn't give a hint of
what went wrong.
Improve this by printing a message with debug information.

Reviewed-by: Peter Oberparleiter 
Reviewed-by: Alexander Gordeev 
Signed-off-by: Heiko Carstens 
Signed-off-by: Alexander Gordeev