linux.git/arch/s390/include/asm/setup.h, branch v5.12

s390: unify identity mapping limits handling

2020-11-20T18:19:10+00:00

Currently we have to consider too many different values which
in the end only affect identity mapping size. These are:
1. max_physmem_end - end of physical memory online or standby.
   Always <= end of the last online memory block (get_mem_detect_end()).
2. CONFIG_MAX_PHYSMEM_BITS - the maximum size of physical memory the
   kernel is able to support.
3. "mem=" kernel command line option which limits physical memory usage.
4. OLDMEM_BASE which is a kdump memory limit when the kernel is executed as
   crash kernel.
5. "hsa" size which is a memory limit when the kernel is executed during
   zfcp/nvme dump.

Through out kernel startup and run we juggle all those values at once
but that does not bring any amusement, only confusion and complexity.

Unify all those values to a single one we should really care, that is
our identity mapping size.

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

s390/sclp: provide extended sccb support

2020-11-18T11:16:02+00:00

As the number of cpus increases, the sccb response can exceed 4k for
read cpu and read scp info sclp commands. Hence, all cpu info entries
cant be embedded within a sccb response

Solution:
To overcome this limitation, extended sccb facility is provided by sclp.

1. Check if the extended sccb facility is installed.
2. If extended sccb is installed, perform the read scp and read cpu
   command considering a max sccb length of three page size. This max
   length is based on factors like max cpus, sccb header.
3. If extended sccb is not installed, perform the read scp and read cpu
   sclp command considering a max sccb length of one page size.

Signed-off-by: Sumanth Korikkar 
Reviewed-by: Vasily Gorbik 
Signed-off-by: Heiko Carstens

s390: remove orphaned extern variables declarations

2020-10-02T12:40:48+00:00

arch/s390/kernel/entry.h: suspend_zero_pages - only declaration left
after commit 394216275c7d ("s390: remove broken hibernate / power
management support")

arch/s390/include/asm/setup.h: vmhalt_cmd - only declaration left after
commit 99ca4e582d4a ("[S390] kernel: Shutdown Actions Interface")

arch/s390/include/asm/setup.h: vmpoff_cmd - only declaration left after
commit 99ca4e582d4a ("[S390] kernel: Shutdown Actions Interface")

Signed-off-by: Vasily Gorbik

s390: remove unused _swsusp_reset_dma

2020-09-29T13:00:58+00:00

Since commit 394216275c7d ("s390: remove broken hibernate / power
management support") _swsusp_reset_dma is unused and could be safely
removed.

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

s390/pci: Implement ioremap_wc/prot() with MIO

2020-09-14T08:30:07+00:00

With our current support for the new MIO PCI instructions, write
combining/write back MMIO memory can be obtained via the pci_iomap_wc()
and pci_iomap_wc_range() functions.
This is achieved by using the write back address for a specific bar
as provided in clp_store_query_pci_fn()

These functions are however not widely used and instead drivers often
rely on ioremap_wc() and ioremap_prot(), which on other platforms enable
write combining using a PTE flag set through the pgrprot value.

While we do not have a write combining flag in the low order flag bits
of the PTE like x86_64 does, with MIO support, there is a write back bit
in the physical address (bit 1 on z15) and thus also the PTE.
Which bit is used to toggle write back and whether it is available at
all, is however not fixed in the architecture. Instead we get this
information from the CLP Store Logical Processor Characteristics for PCI
command. When the write back bit is not provided we fall back to the
existing behavior.

Signed-off-by: Niklas Schnelle 
Reviewed-by: Pierre Morel 
Reviewed-by: Gerald Schaefer 
Signed-off-by: Vasily Gorbik

s390: prevent leaking kernel address in BEAR

2020-03-10T14:16:25+00:00

When userspace executes a syscall or gets interrupted,
BEAR contains a kernel address when returning to userspace.
This make it pretty easy to figure out where the kernel is
mapped even with KASLR enabled. To fix this, add lpswe to
lowcore and always execute it there, so userspace sees only
the lowcore address of lpswe. For this we have to extend
both critical_cleanup and the SWITCH_ASYNC macro to also check
for lpswe addresses in lowcore.

Fixes: b2d24b97b2a9 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Cc:  # v5.2+
Reviewed-by: Gerald Schaefer 
Signed-off-by: Sven Schnelle 
Signed-off-by: Vasily Gorbik

s390/boot: add dfltcc= kernel command line parameter

2020-01-31T18:30:40+00:00

Add the new kernel command line parameter 'dfltcc=' to configure s390
zlib hardware support.

Format: { on | off | def_only | inf_only | always }
 on:       s390 zlib hardware support for compression on
           level 1 and decompression (default)
 off:      No s390 zlib hardware support
 def_only: s390 zlib hardware support for deflate
           only (compression on level 1)
 inf_only: s390 zlib hardware support for inflate
           only (decompression)
 always:   Same as 'on' but ignores the selected compression
           level always using hardware support (used for debugging)

Link: http://lkml.kernel.org/r/20200103223334.20669-5-zaslonko@linux.ibm.com
Signed-off-by: Mikhail Zaslonko 
Cc: Chris Mason 
Cc: Christian Borntraeger 
Cc: David Sterba 
Cc: Eduard Shishkin 
Cc: Heiko Carstens 
Cc: Ilya Leoshkevich 
Cc: Josef Bacik 
Cc: Richard Purdie 
Cc: Vasily Gorbik 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

s390: remove last diag 0x44 caller

2019-12-11T18:53:24+00:00

diag 0x44 is a voluntary undirected yield of a virtual CPU. This has
caused a lot of performance issues in the past.

There is only one caller left, and that one is only executed if diag
0x9c (directed yield) is not present. Given that all hypervisors
implement diag 0x9c anyway, remove the last diag 0x44 to avoid that
more callers will be added.

Worst case that could happen now, if diag 0x9c is not present, is that
a virtual CPU would loop a bit instead of giving its time slice up.

diag 0x44 statistics in debugfs are kept and will always be zero, so
that user space can tell that there are no calls.

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

Merge tag 's390-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2019-09-17T21:04:43+00:00

Pull s390 updates from Vasily Gorbik:

 - Add support for IBM z15 machines.

 - Add SHA3 and CCA AES cipher key support in zcrypt and pkey
   refactoring.

 - Move to arch_stack_walk infrastructure for the stack unwinder.

 - Various kasan fixes and improvements.

 - Various command line parsing fixes.

 - Improve decompressor phase debuggability.

 - Lift no bss usage restriction for the early code.

 - Use refcount_t for reference counters for couple of places in mm
   code.

 - Logging improvements and return code fix in vfio-ccw code.

 - Couple of zpci fixes and minor refactoring.

 - Remove some outdated documentation.

 - Fix secure boot detection.

 - Other various minor code clean ups.

* tag 's390-5.4-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (48 commits)
  s390: remove pointless drivers-y in drivers/s390/Makefile
  s390/cpum_sf: Fix line length and format string
  s390/pci: fix MSI message data
  s390: add support for IBM z15 machines
  s390/crypto: Support for SHA3 via CPACF (MSA6)
  s390/startup: add pgm check info printing
  s390/crypto: xts-aes-s390 fix extra run-time crypto self tests finding
  vfio-ccw: fix error return code in vfio_ccw_sch_init()
  s390: vfio-ap: fix warning reset not completed
  s390/base: remove unused s390_base_mcck_handler
  s390/sclp: Fix bit checked for has_sipl
  s390/zcrypt: fix wrong handling of cca cipher keygenflags
  s390/kasan: add kdump support
  s390/setup: avoid using strncmp with hardcoded length
  s390/sclp: avoid using strncmp with hardcoded length
  s390/module: avoid using strncmp with hardcoded length
  s390/pci: avoid using strncmp with hardcoded length
  s390/kaslr: reserve memory for kasan usage
  s390/mem_detect: provide single get_mem_detect_end
  s390/cmma: reuse kstrtobool for option value parsing
  ...

s390: move vmalloc option parsing to startup code

2019-08-21T10:41:43+00:00

Few other crucial memory setup options are already handled in
the startup code. Those values are needed by kaslr and kasan
implementations. "vmalloc" is the last piece required for future
improvements such as early decision on kernel page levels depth required
for actual memory setup, as well as vmalloc memory area access monitoring
in kasan.

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