Commit graph

825315 commits

Author SHA1 Message Date
Martin Schwidefsky
e21f8baf8d s390/bug: add entry size to the __bug_table section
Change the __EMIT_BUG inline assembly to emit mergeable __bug_table
entries with type @progbits and specify the size of each entry.
The entry size is encoded sh_entsize field of the section definition,
it allows to identify which struct bug_entry to use to decode the
entries. This will be needed for the objtool support.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-05-02 13:54:11 +02:00
Martin Schwidefsky
bf72630130 s390: use proper expoline sections for .dma code
The text_dma.S code uses its own macro to generate an inline version of an
expoline. To make it easier to identify all expolines in the kernel use a
thunk and a branch to the thunk just like the rest of the kernel code does
it.

The name of the text_dma.S expoline thunk is __dma__s390_indirect_jump_r14
and the section is named .dma.text.__s390_indirect_jump_r14.

This will be needed for the objtool support.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-05-02 13:54:11 +02:00
Martin Schwidefsky
40a3abf751 s390/nospec: rename assembler generated expoline thunks
The assembler version of the expoline thunk use the naming
__s390x_indirect_jump_rxuse_ry while the compiler generates names
like __s390_indirect_jump_rx_use_ry. Make the naming more consistent.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-05-02 13:54:11 +02:00
Martin Schwidefsky
26a374ae7a s390: add missing ENDPROC statements to assembler functions
The assembler code in arch/s390 misses proper ENDPROC statements
to properly end functions in a few places. Add them.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-05-02 13:54:11 +02:00
Gerald Schaefer
7a5da02de8 locking/lockdep: check for freed initmem in static_obj()
The following warning occurred on s390:
WARNING: CPU: 0 PID: 804 at kernel/locking/lockdep.c:1025 lockdep_register_key+0x30/0x150

This is because the check in static_obj() assumes that all memory within
[_stext, _end] belongs to static objects, which at least for s390 isn't
true. The init section is also part of this range, and freeing it allows
the buddy allocator to allocate memory from it. We have virt == phys for
the kernel on s390, so that such allocations would then have addresses
within the range [_stext, _end].

To fix this, introduce arch_is_kernel_initmem_freed(), similar to
arch_is_kernel_text/data(), and add it to the checks in static_obj().
This will always return 0 on architectures that do not define
arch_is_kernel_initmem_freed. On s390, it will return 1 if initmem has
been freed and the address is in the range [__init_begin, __init_end].

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
b2d24b97b2 s390/kernel: add support for kernel address space layout randomization (KASLR)
This patch adds support for relocating the kernel to a random address.
The random kernel offset is obtained from cpacf, using either TRNG, PRNO,
or KMC_PRNG, depending on supported MSA level.

KERNELOFFSET is added to vmcoreinfo, for crash --kaslr support.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
a80313ff91 s390/kernel: introduce .dma sections
With a relocatable kernel that could reside at any place in memory, code
and data that has to stay below 2 GB needs special handling.

This patch introduces .dma sections for such text, data and ex_table.
The sections will be part of the decompressor kernel, so they will not
be relocated and stay below 2 GB. Their location is passed over to the
decompressed / relocated kernel via the .boot.preserved.data section.

The duald and aste for control register setup also need to stay below
2 GB, so move the setup code from arch/s390/kernel/head64.S to
arch/s390/boot/head.S. The duct and linkage_stack could reside above
2 GB, but their content has to be preserved for the decompresed kernel,
so they are also moved into the .dma section.

The start and end address of the .dma sections is added to vmcoreinfo,
for crash support, to help debugging in case the kernel crashed there.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
087c4d7423 s390/sclp: do not use static sccbs
The sccbs for init/read/sdias/early have to be located below 2 GB, and
they are currently defined as a static buffer.

With a relocatable kernel that could reside at any place in memory, this
will no longer guarantee the location below 2 GB, so use a dynamic
GFP_DMA allocation instead.

The sclp_early_sccb buffer needs special handling, as it can be used
very early, and by both the decompressor and also the decompressed
kernel. Therefore, a fixed 4 KB buffer is introduced at 0x11000, the
former PARMAREA_END. The new PARMAREA_END is now 0x12000, and it is
renamed to HEAD_END, as it is rather the end of head.S and not the end
of the parmarea.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
fd3d2742d5 s390/kprobes: use static buffer for insn_page
With a relocatable kernel that could reside at any place in memory, the
current logic for allocating a kprobes insn_page does not work. The
GFP_DMA allocated buffer might be more than 2 GB away from the kernel.

Use a static buffer for the insn_page instead.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
ff4a742dde s390/kernel: convert SYSCALL and PGM_CHECK handlers to .quad
With a relocatable kernel that could reside at any place in memory, the
storage size for the SYSCALL and PGM_CHECK handlers needs to be
increased from .long to .quad.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Gerald Schaefer
805bc0bc23 s390/kernel: build a relocatable kernel
This patch adds support for building a relocatable kernel with -fPIE.
The kernel will be relocated to 0 early in the boot process.

Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Reviewed-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:10 +02:00
Sebastian Ott
833b441ec0 s390: enable processes for mio instructions
Allow for userspace to use PCI MIO instructions.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
5627130380 s390/pci: add parameter to disable usage of MIO instructions
Allow users to disable usage of MIO instructions by specifying pci=nomio
at the kernel command line.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
71ba41c9b1 s390/pci: provide support for MIO instructions
Provide support for PCI I/O instructions that work on mapped IO addresses.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
c475f1770a s390/ism: move oddities of device IO to wrapper function
ISM devices are special in how they access PCI memory space. Provide
wrappers for handling commands to the device. No functional change.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
81deca12c2 s390/pci: move io address mapping code to pci_insn.c
This is a preparation patch for usage of new pci instructions.
No functional change.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
fbfe07d440 s390/pci: add parameter to force floating irqs
Provide a kernel parameter to force the usage of floating interrupts.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
07e3ec3acb s390/pci: gather statistics for floating vs directed irqs
Gather statistics to distinguish floating and directed interrupts.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
914b7dd07e s390: show statistics for MSI IRQs
Improve /proc/interrupts on s390 to show statistics for individual
MSI interrupts.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
e979ce7bce s390/pci: provide support for CPU directed interrupts
Up until now all interrupts on s390 have been floating. For MSI interrupts
we've used a global summary bit vector (with a bit for each function) and
a per-function interrupt bit vector (with a bit per MSI).

This patch introduces a new IRQ delivery mode: CPU directed interrupts.
In this new mode a per-CPU interrupt bit vector is used (with a bit per
MSI per function). Further it is now possible to direct an IRQ to a
specific CPU so we can finally support IRQ affinity.

If an interrupt can't be delivered because the appointed CPU is occupied
by a hypervisor the interrupt is delivered floating. For this a global
summary bit vector is used (with a bit per CPU).

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
414cbd1e3d s390/airq: provide cacheline aligned ivs
Provide the ability to create cachesize aligned interrupt vectors.
These will be used for per-CPU interrupt vectors.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
b1f548645c s390/pci: clarify interrupt vector usage
Rename and clarify the usage of the interrupt bit vectors. Also change
the array of the per-function bit vectors to be dynamically allocated.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
30e63ef2ef s390/airq: recognize directed interrupts
Add an extra parameter for airq handlers to recognize
floating vs. directed interrupts.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
0a9fddfaa8 s390/sclp: detect DIRQ facility
Detect the adapter CPU directed interruption facility.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
c840927cf5 s390/pci: move everything irq related to pci_irq.c
Move everything interrupt related from pci.c to pci_irq.c.
No functional change.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
066ee72aec s390/pci: remove unused define
No users of pr_debug in that file.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Sebastian Ott
6324b4de6d s390/pci: mark command line parser data __initdata
No point to keep that around.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:47:01 +02:00
Philipp Rudo
c9896acc78 s390/ipl: Provide has_secure sysfs attribute
Provide an interface for userspace so it can find out if a machine is
capeable of doing secure boot. The interface is, for example, needed for
zipl so it can find out which file format it can/should write to disk.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:44:04 +02:00
Philipp Rudo
268a784049 s390/kexec_file: Disable kexec_load when IPLed secure
A kernel loaded via kexec_load cannot be verified. Thus disable kexec_load
systemcall in kernels which where IPLed securely. Use the IMA mechanism to
do so.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:44:03 +02:00
Philipp Rudo
99feaa717e s390/kexec_file: Create ipl report and pass to next kernel
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:44:02 +02:00
Philipp Rudo
e23a8020ce s390/kexec_file: Signature verification prototype
Add kernel signature verification to kexec_file. The verification is based
on module signature verification and works with kernel images signed via
scripts/sign-file.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:44:01 +02:00
Philipp Rudo
653beba24d s390/kexec_file: Load new kernel to absolute 0
The leading 64 kB of a kernel image doesn't contain any data needed to boot
the new kernel when it was loaded via kexec_file. Thus kexec_file currently
strips them off before loading the image. Keep the leading 64 kB in order
to be able to pass a ipl_report to the next kernel.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:44:00 +02:00
Philipp Rudo
8e49642613 s390/kexec_file: Unify loader code
s390_image_load and s390_elf_load have the same code to load the different
components. Combine this functionality in one shared function.

While at it move kexec_file_update_kernel into the new function as well.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:59 +02:00
Philipp Rudo
d0d249d75d s390/kexec_file: Simplify parmarea access
Access the parmarea in head.S via a struct instead of individual offsets.

While at it make the fields in the parmarea .quads.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:57 +02:00
Philipp Rudo
4c0f032d49 s390/purgatory: Omit use of bin2c
Omit use of script/bin2c hack. Directly include into assembler file instead.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:55 +02:00
Philipp Rudo
61f3f8fc22 s390/purgatory: Reduce purgatory size
The purgatory is compiled into the vmlinux and keept in memory all the time
during runtime. Thus any section not needed to load the purgatory
unnecessarily bloats up its foot print in file- and memorysize. Reduce the
purgatory size by stripping the unneeded sections from the purgatory.

This reduces the purgatories size by ~33%.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:53 +02:00
Philipp Rudo
729829d775 s390/kexec_file: Fix detection of text segment in ELF loader
To register data for the next kernel (command line, oldmem_base, etc.) the
current kernel needs to find the ELF segment that contains head.S. This is
currently done by checking ifor 'phdr->p_paddr == 0'. This works fine for
the current kernel build but in theory the first few pages could be
skipped. Make the detection more robust by checking if the entry point lies
within the segment.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:46 +02:00
Philipp Rudo
6339a3889a s390/kexec_file: Fix potential segment overlap in ELF loader
When loading an ELF image via kexec_file the segment alignment is ignored
in the calculation for the load address of the next segment. When there are
multiple segments this can lead to segment overlap and thus load failure.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Fixes: 8be0188271 ("s390/kexec_file: Add ELF loader")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-29 10:43:43 +02:00
Philipp Rudo
f3df44e7c9 s390/zcore: Rename ipl_block to mitigate name collision
With git commit 1e941d3949
"s390: move ipl block to .boot.preserved.data section" the earl_ipl_block
got renamed to ipl_block and became publicly available via boot_data.h.
This might cause problems with zcore, which has it's own ipl_block
variable. Thus rename the ipl_block in zcore to prevent name collision
and highlight that it's only used locally.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Fixes: 1e941d3949 ("s390: move ipl block to .boot.preserved.data section")
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
f678068652 s390/boot: pad bzImage to 4K
In order to be able to sign the bzImage independent of the block size
of the IPL device, align the bzImage to 4096 bytes.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
937347ac56 s390/ipl: add helper functions to create an IPL report
PR: Adjusted to the use in kexec_file later.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
9641b8cc73 s390/ipl: read IPL report at early boot
Read the IPL Report block provided by secure-boot, add the entries
of the certificate list to the system key ring and print the list
of components.

PR: Adjust to Vasilys bootdata_preserved patch set. Preserve ipl_cert_list
for later use in kexec_file.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
d29af5b7a8 s390/ipl: add definitions for the IPL report block
To transport the information required for secure boot a new IPL report
will be created at boot time. It will be written to memory right after
the IPL parameter block. To work with the IPL report a couple of
additional structure definitions are added the the uapi/ipl.h header.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
5f1207fbe7 s390/ipl: provide uapi header for list directed IPL
The IPL parameter block is used as an interface between Linux and
the machine to query and change the boot device and boot options.
To be able to create IPL parameter block in user space and pass it
as segment to kexec provide an uapi header with proper structure
definitions for the block.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
86c74d869d s390/ipl: make ipl_info less confusing
The ipl_info union in struct ipl_parameter_block has the same name as
the struct ipl_info. This does not help while reading the code and the
union in struct ipl_parameter_block does not need to be named. Drop
the name from the union.

Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-26 12:34:05 +02:00
Martin Schwidefsky
a8fd61688d s390: report new CPU capabilities
Add hardware capability bits and features tags to /proc/cpuinfo
for 4 new CPU features:
  "Vector-Enhancements Facility 2" (tag "vxe2", hwcap 2^15)
  "Vector-Packed-Decimal-Enhancement Facility" (tag "vxp", hwcap 2^16)
  "Enhanced-Sort Facility" (tag "sort", hwcap 2^17)
  "Deflate-Conversion Facility" (tag "dflt", hwcap 2^18)

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-25 15:34:10 +02:00
Harald Freudenberger
769f020b6c s390/crypto: use TRNG for seeding/reseeding
With the z14 machine there came also a CPACF hardware extension
which provides a True Random Number Generator. This TRNG can
be accessed with a new subfunction code within the CPACF prno
instruction and provides random data with very high entropy.

So if there is a TRNG available, let's use it for initial seeding
and reseeding instead of the current implementation which tries
to generate entropy based on stckf (store clock fast) jitters.

For details about the amount of data needed and pulled for
seeding and reseeding there can be explaining comments in the
code found.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-25 15:34:09 +02:00
Harald Freudenberger
23d1aee92b s390/crypto: rework generate_entropy function for pseudo random dd
Here is a rework of the generate_entropy function of the pseudo random
device driver exploiting the prno CPACF instruction.

George Spelvin pointed out some issues with the existing
implementation. One point was, that the buffer used to store the stckf
values is 2 pages which are initially filled with get_random_bytes()
for each 64 byte junk produced by the function. Another point was that
the stckf values only carry entropy in the LSB and thus a buffer of
2 pages is not really needed. Then there was a comment about the use
of the kimd cpacf function without proper initialization.

The rework addresses these points and now one page is used and only
one half of this is filled with get_random_bytes() on each chunk of 64
bytes requested data. The other half of the page is filled with stckf
values exored into with an overlap of 4 bytes. This can be done due to
the fact that only the lower 4 bytes carry entropy we need.  For more
details about the algorithm used, see the header of the function.

The generate_entropy() function now uses the cpacf function klmd with
proper initialization of the parameter block to perform the sha512
hash.

George also pointed out some issues with the internal buffers used for
seeding and reads. These buffers are now zeroed with memzero_implicit
after use.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Reported-by: George Spelvin <lkml@sdf.org>
Suggested-by: George Spelvin <lkml@sdf.org>
Reviewed-by: Patrick Steuer <steuer@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2019-04-25 15:34:08 +02:00
Martin Schwidefsky
5513bc8eb4 - support for sending halt/clear requests to the device
- various bug fixes
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Merge tag 'vfio-ccw-20190425' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/vfio-ccw into features

Pull vfio-ccw from Cornelia Huck with the following changes:

 - support for sending halt/clear requests to the device

 - various bug fixes
2019-04-25 13:45:09 +02:00
Farhan Ali
d1ffa760d2 vfio-ccw: Prevent quiesce function going into an infinite loop
The quiesce function calls cio_cancel_halt_clear() and if we
get an -EBUSY we go into a loop where we:
	- wait for any interrupts
	- flush all I/O in the workqueue
	- retry cio_cancel_halt_clear

During the period where we are waiting for interrupts or
flushing all I/O, the channel subsystem could have completed
a halt/clear action and turned off the corresponding activity
control bits in the subchannel status word. This means the next
time we call cio_cancel_halt_clear(), we will again start by
calling cancel subchannel and so we can be stuck between calling
cancel and halt forever.

Rather than calling cio_cancel_halt_clear() immediately after
waiting, let's try to disable the subchannel. If we succeed in
disabling the subchannel then we know nothing else can happen
with the device.

Suggested-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <4d5a4b98ab1b41ac6131b5c36de18b76c5d66898.1555449329.git.alifm@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
2019-04-24 14:18:51 +02:00