linux-stable.git/arch/s390/kernel/setup.c, branch linux-4.4.y

s390/setup: avoid using memblock_enforce_memory_limit

2021-12-08T07:44:07+00:00

[ Upstream commit 5dbc4cb4667457b0c53bcd7bff11500b3c362975 ]

There is a difference in how architectures treat "mem=" option. For some
that is an amount of online memory, for s390 and x86 this is the limiting
max address. Some memblock api like memblock_enforce_memory_limit()
take limit argument and explicitly treat it as the size of online memory,
and use __find_max_addr to convert it to an actual max address. Current
s390 usage:

memblock_enforce_memory_limit(memblock_end_of_DRAM());

yields different results depending on presence of memory holes (offline
memory blocks in between online memory). If there are no memory holes
limit == max_addr in memblock_enforce_memory_limit() and it does trim
online memory and reserved memory regions. With memory holes present it
actually does nothing.

Since we already use memblock_remove() explicitly to trim online memory
regions to potential limit (think mem=, kdump, addressing limits, etc.)
drop the usage of memblock_enforce_memory_limit() altogether. Trimming
reserved regions should not be required, since we now use
memblock_set_current_limit() to limit allocations and any explicit memory
reservations above the limit is an actual problem we should not hide.

Reviewed-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens 
Signed-off-by: Sasha Levin

s390/init: add missing __init annotations

2020-10-01T09:11:57+00:00

[ Upstream commit fcb2b70cdb194157678fb1a75f9ff499aeba3d2a ]

Add __init to reserve_memory_end, reserve_oldmem and remove_oldmem.
Sometimes these functions are not inlined, and then the build
complains about section mismatch.

Signed-off-by: Ilya Leoshkevich 
Signed-off-by: Heiko Carstens 
Signed-off-by: Vasily Gorbik 
Signed-off-by: Sasha Levin

s390/early: improve machine detection

2019-02-06T18:43:03+00:00

commit 03aa047ef2db4985e444af6ee1c1dd084ad9fb4c upstream.

Right now the early machine detection code check stsi 3.2.2 for "KVM"
and set MACHINE_IS_VM if this is different. As the console detection
uses diagnose 8 if MACHINE_IS_VM returns true this will crash Linux
early for any non z/VM system that sets a different value than KVM.
So instead of assuming z/VM, do not set any of MACHINE_IS_LPAR,
MACHINE_IS_VM, or MACHINE_IS_KVM.

CC: stable@vger.kernel.org
Reviewed-by: Heiko Carstens 
Signed-off-by: Christian Borntraeger 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390: correct nospec auto detection init order

2018-04-29T05:50:04+00:00

[ Upstream commit 6a3d1e81a434fc311f224b8be77258bafc18ccc6 ]

With CONFIG_EXPOLINE_AUTO=y the call of spectre_v2_auto_early() via
early_initcall is done *after* the early_param functions. This
overwrites any settings done with the nobp/no_spectre_v2/spectre_v2
parameters. The code patching for the kernel is done after the
evaluation of the early parameters but before the early_initcall
is done. The end result is a kernel image that is patched correctly
but the kernel modules are not.

Make sure that the nospec auto detection function is called before the
early parameters are evaluated and before the code patching is done.

Fixes: 6e179d64126b ("s390: add automatic detection of the spectre defense")
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390: introduce execute-trampolines for branches

2018-04-29T05:50:03+00:00

[ Upstream commit f19fbd5ed642dc31c809596412dab1ed56f2f156 ]

Add CONFIG_EXPOLINE to enable the use of the new -mindirect-branch= and
-mfunction_return= compiler options to create a kernel fortified against
the specte v2 attack.

With CONFIG_EXPOLINE=y all indirect branches will be issued with an
execute type instruction. For z10 or newer the EXRL instruction will
be used, for older machines the EX instruction. The typical indirect
call

	basr	%r14,%r1

is replaced with a PC relative call to a new thunk

	brasl	%r14,__s390x_indirect_jump_r1

The thunk contains the EXRL/EX instruction to the indirect branch

__s390x_indirect_jump_r1:
	exrl	0,0f
	j	.
0:	br	%r1

The detour via the execute type instruction has a performance impact.
To get rid of the detour the new kernel parameter "nospectre_v2" and
"spectre_v2=[on,off,auto]" can be used. If the parameter is specified
the kernel and module code will be patched at runtime.

Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390/alternative: use a copy of the facility bit mask

2018-04-29T05:50:03+00:00

[ Upstream commit cf1489984641369611556bf00c48f945c77bcf02 ]

To be able to switch off specific CPU alternatives with kernel parameters
make a copy of the facility bit mask provided by STFLE and use the copy
for the decision to apply an alternative.

Reviewed-by: David Hildenbrand 
Reviewed-by: Cornelia Huck 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390: introduce CPU alternatives

2018-04-29T05:50:02+00:00

[ Upstream commit 686140a1a9c41d85a4212a1c26d671139b76404b ]

Implement CPU alternatives, which allows to optionally patch newer
instructions at runtime, based on CPU facilities availability.

A new kernel boot parameter "noaltinstr" disables patching.

Current implementation is derived from x86 alternatives. Although
ideal instructions padding (when altinstr is longer then oldinstr)
is added at compile time, and no oldinstr nops optimization has to be
done at runtime. Also couple of compile time sanity checks are done:
1. oldinstr and altinstr must be <= 254 bytes long,
2. oldinstr and altinstr must not have an odd length.

alternative(oldinstr, altinstr, facility);
alternative_2(oldinstr, altinstr1, facility1, altinstr2, facility2);

Both compile time and runtime padding consists of either 6/4/2 bytes nop
or a jump (brcl) + 2 bytes nop filler if padding is longer then 6 bytes.

.altinstructions and .altinstr_replacement sections are part of
__init_begin : __init_end region and are freed after initialization.

Signed-off-by: Vasily Gorbik 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390: use correct input data address for setup_randomness

2017-03-15T01:57:12+00:00

commit 4920e3cf77347d7d7373552d4839e8d832321313 upstream.

The current implementation of setup_randomness uses the stack address
and therefore the pointer to the SYSIB 3.2.2 block as input data
address. Furthermore the length of the input data is the number of
virtual-machine description blocks which is typically one.

This means that typically a single zero byte is fed to
add_device_randomness.

Fix both of these and use the address of the first virtual machine
description block as input data address and also use the correct
length.

Fixes: bcfcbb6bae64 ("s390: add system information as device randomness")
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390: make setup_randomness work

2017-03-15T01:57:12+00:00

commit da8fd820f389a0e29080b14c61bf5cf1d8ef5ca1 upstream.

Commit bcfcbb6bae64 ("s390: add system information as device
randomness") intended to add some virtual machine specific information
to the randomness pool.

Unfortunately it uses the page allocator before it is ready to use. In
result the page allocator always returns NULL and the setup_randomness
function never adds anything to the randomness pool.

To fix this use memblock_alloc and memblock_free instead.

Fixes: bcfcbb6bae64 ("s390: add system information as device randomness")
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman

s390/cpumf: add missing lpp magic initialization

2016-04-12T16:08:36+00:00

commit 8f100bb1ff27873dd71f636da670e503b9ade3c6 upstream.

Add the missing lpp magic initialization for cpu 0. Without this all
samples on cpu 0 do not have the most significant bit set in the
program parameter field, which we use to distinguish between guest and
host samples if the pid is also 0.

We did initialize the lpp magic in the absolute zero lowcore but
forgot that when switching to the allocated lowcore on cpu 0 only.

Reported-by: Shu Juan Zhang 
Acked-by: Christian Borntraeger 
Fixes: e22cf8ca6f75 ("s390/cpumf: rework program parameter setting to detect guest samples")
Signed-off-by: Heiko Carstens 
Signed-off-by: Martin Schwidefsky 
Signed-off-by: Greg Kroah-Hartman