Commit Graph

301 Commits

Author SHA1 Message Date
Heiko Carstens 04dabb4261 s390/bug: Implement __WARN_printf()
This is the s390 variant of commit 5b472b6e5b ("x86_64/bug: Implement
__WARN_printf()"). See the x86 commit for the general idea; there are only
implementation details which are different.

With the new exception based __WARN_printf() implementation the generated
code for a simple WARN() is simplified.

For example:

void foo(int a) { WARN(a, "bar"); }

Before this change the generated code looks like this:

0000000000000210 <foo>:
 210:   c0 04 00 00 00 00       jgnop   210 <foo>
 216:   ec 26 00 06 00 7c       cgijne  %r2,0,222 <foo+0x12>
 21c:   c0 f4 00 00 00 00       jg      21c <foo+0xc>
                        21e: R_390_PC32DBL      __s390_indirect_jump_r14+0x2
 222:   eb ef f0 88 00 24       stmg    %r14,%r15,136(%r15)
 228:   b9 04 00 ef             lgr     %r14,%r15
 22c:   e3 f0 ff e8 ff 71       lay     %r15,-24(%r15)
 232:   e3 e0 f0 98 00 24       stg     %r14,152(%r15)
 238:   c0 20 00 00 00 00       larl    %r2,238 <foo+0x28>
                        23a: R_390_PC32DBL      .LC48+0x2
 23e:   c0 e5 00 00 00 00       brasl   %r14,23e <foo+0x2e>
                        240: R_390_PLT32DBL     __warn_printk+0x2
 244:   af 00 00 00             mc      0,0
 248:   eb ef f0 a0 00 04       lmg     %r14,%r15,160(%r15)
 24e:   c0 f4 00 00 00 00       jg      24e <foo+0x3e>
                        250: R_390_PC32DBL      __s390_indirect_jump_r14+0x2

With this change the generated code looks like this:

0000000000000210 <foo>:
 210:   c0 04 00 00 00 00       jgnop   210 <foo>
 216:   ec 26 00 06 00 7c       cgijne  %r2,0,222 <foo+0x12>
 21c:   c0 f4 00 00 00 00       jg      21c <foo+0xc>
                        21e: R_390_PC32DBL      __s390_indirect_jump_r14+0x2
 222:   c0 20 00 00 00 00       larl    %r2,222 <foobar+0x12>
                        224: R_390_PC32DBL      __bug_table+0x2
 228:   c0 f4 00 00 00 00       jg      228 <foobar+0x18>
                        22a: R_390_PLT32DBL     __WARN_trap+0x2

Downside is that the call trace now starts at __WARN_trap():

------------[ cut here ]------------
bar
WARNING: arch/s390/kernel/setup.c:1017 at 0x0, CPU#0: swapper/0/0
...
Krnl PSW : 0704c00180000000 000003ffe0f6a3b4 (__WARN_trap+0x4/0x10)
...
Krnl Code: 000003ffe0f6a3ac: 0707                bcr     0,%r7
           000003ffe0f6a3ae: 0707                bcr     0,%r7
          *000003ffe0f6a3b0: af000001            mc      1,0
          >000003ffe0f6a3b4: 07fe                bcr     15,%r14
           000003ffe0f6a3b6: 47000700            bc      0,1792
           000003ffe0f6a3ba: 0707                bcr     0,%r7
           000003ffe0f6a3bc: 0707                bcr     0,%r7
           000003ffe0f6a3be: 0707                bcr     0,%r7
Call Trace:
 [<000003ffe0f6a3b4>] __WARN_trap+0x4/0x10
([<000003ffe185a54c>] start_kernel+0x53c/0x5d8)
 [<000003ffe010002e>] startup_continue+0x2e/0x40

Which isn't too helpful. This can be addressed by just skipping __WARN_trap(),
which will be addressed in a later patch.

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2026-01-27 12:16:16 +01:00
Linus Torvalds 51d90a15fe Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Paolo Bonzini:
 "ARM:

   - Support for userspace handling of synchronous external aborts
     (SEAs), allowing the VMM to potentially handle the abort in a
     non-fatal manner

   - Large rework of the VGIC's list register handling with the goal of
     supporting more active/pending IRQs than available list registers
     in hardware. In addition, the VGIC now supports EOImode==1 style
     deactivations for IRQs which may occur on a separate vCPU than the
     one that acked the IRQ

   - Support for FEAT_XNX (user / privileged execute permissions) and
     FEAT_HAF (hardware update to the Access Flag) in the software page
     table walkers and shadow MMU

   - Allow page table destruction to reschedule, fixing long
     need_resched latencies observed when destroying a large VM

   - Minor fixes to KVM and selftests

  Loongarch:

   - Get VM PMU capability from HW GCFG register

   - Add AVEC basic support

   - Use 64-bit register definition for EIOINTC

   - Add KVM timer test cases for tools/selftests

  RISC/V:

   - SBI message passing (MPXY) support for KVM guest

   - Give a new, more specific error subcode for the case when in-kernel
     AIA virtualization fails to allocate IMSIC VS-file

   - Support KVM_DIRTY_LOG_INITIALLY_SET, enabling dirty log gradually
     in small chunks

   - Fix guest page fault within HLV* instructions

   - Flush VS-stage TLB after VCPU migration for Andes cores

  s390:

   - Always allocate ESCA (Extended System Control Area), instead of
     starting with the basic SCA and converting to ESCA with the
     addition of the 65th vCPU. The price is increased number of exits
     (and worse performance) on z10 and earlier processor; ESCA was
     introduced by z114/z196 in 2010

   - VIRT_XFER_TO_GUEST_WORK support

   - Operation exception forwarding support

   - Cleanups

  x86:

   - Skip the costly "zap all SPTEs" on an MMIO generation wrap if MMIO
     SPTE caching is disabled, as there can't be any relevant SPTEs to
     zap

   - Relocate a misplaced export

   - Fix an async #PF bug where KVM would clear the completion queue
     when the guest transitioned in and out of paging mode, e.g. when
     handling an SMI and then returning to paged mode via RSM

   - Leave KVM's user-return notifier registered even when disabling
     virtualization, as long as kvm.ko is loaded. On reboot/shutdown,
     keeping the notifier registered is ok; the kernel does not use the
     MSRs and the callback will run cleanly and restore host MSRs if the
     CPU manages to return to userspace before the system goes down

   - Use the checked version of {get,put}_user()

   - Fix a long-lurking bug where KVM's lack of catch-up logic for
     periodic APIC timers can result in a hard lockup in the host

   - Revert the periodic kvmclock sync logic now that KVM doesn't use a
     clocksource that's subject to NTP corrections

   - Clean up KVM's handling of MMIO Stale Data and L1TF, and bury the
     latter behind CONFIG_CPU_MITIGATIONS

   - Context switch XCR0, XSS, and PKRU outside of the entry/exit fast
     path; the only reason they were handled in the fast path was to
     paper of a bug in the core #MC code, and that has long since been
     fixed

   - Add emulator support for AVX MOV instructions, to play nice with
     emulated devices whose guest drivers like to access PCI BARs with
     large multi-byte instructions

  x86 (AMD):

   - Fix a few missing "VMCB dirty" bugs

   - Fix the worst of KVM's lack of EFER.LMSLE emulation

   - Add AVIC support for addressing 4k vCPUs in x2AVIC mode

   - Fix incorrect handling of selective CR0 writes when checking
     intercepts during emulation of L2 instructions

   - Fix a currently-benign bug where KVM would clobber SPEC_CTRL[63:32]
     on VMRUN and #VMEXIT

   - Fix a bug where KVM corrupt the guest code stream when re-injecting
     a soft interrupt if the guest patched the underlying code after the
     VM-Exit, e.g. when Linux patches code with a temporary INT3

   - Add KVM_X86_SNP_POLICY_BITS to advertise supported SNP policy bits
     to userspace, and extend KVM "support" to all policy bits that
     don't require any actual support from KVM

  x86 (Intel):

   - Use the root role from kvm_mmu_page to construct EPTPs instead of
     the current vCPU state, partly as worthwhile cleanup, but mostly to
     pave the way for tracking per-root TLB flushes, and elide EPT
     flushes on pCPU migration if the root is clean from a previous
     flush

   - Add a few missing nested consistency checks

   - Rip out support for doing "early" consistency checks via hardware
     as the functionality hasn't been used in years and is no longer
     useful in general; replace it with an off-by-default module param
     to WARN if hardware fails a check that KVM does not perform

   - Fix a currently-benign bug where KVM would drop the guest's
     SPEC_CTRL[63:32] on VM-Enter

   - Misc cleanups

   - Overhaul the TDX code to address systemic races where KVM (acting
     on behalf of userspace) could inadvertantly trigger lock contention
     in the TDX-Module; KVM was either working around these in weird,
     ugly ways, or was simply oblivious to them (though even Yan's
     devilish selftests could only break individual VMs, not the host
     kernel)

   - Fix a bug where KVM could corrupt a vCPU's cpu_list when freeing a
     TDX vCPU, if creating said vCPU failed partway through

   - Fix a few sparse warnings (bad annotation, 0 != NULL)

   - Use struct_size() to simplify copying TDX capabilities to userspace

   - Fix a bug where TDX would effectively corrupt user-return MSR
     values if the TDX Module rejects VP.ENTER and thus doesn't clobber
     host MSRs as expected

  Selftests:

   - Fix a math goof in mmu_stress_test when running on a single-CPU
     system/VM

   - Forcefully override ARCH from x86_64 to x86 to play nice with
     specifying ARCH=x86_64 on the command line

   - Extend a bunch of nested VMX to validate nested SVM as well

   - Add support for LA57 in the core VM_MODE_xxx macro, and add a test
     to verify KVM can save/restore nested VMX state when L1 is using
     5-level paging, but L2 is not

   - Clean up the guest paging code in anticipation of sharing the core
     logic for nested EPT and nested NPT

  guest_memfd:

   - Add NUMA mempolicy support for guest_memfd, and clean up a variety
     of rough edges in guest_memfd along the way

   - Define a CLASS to automatically handle get+put when grabbing a
     guest_memfd from a memslot to make it harder to leak references

   - Enhance KVM selftests to make it easer to develop and debug
     selftests like those added for guest_memfd NUMA support, e.g. where
     test and/or KVM bugs often result in hard-to-debug SIGBUS errors

   - Misc cleanups

  Generic:

   - Use the recently-added WQ_PERCPU when creating the per-CPU
     workqueue for irqfd cleanup

   - Fix a goof in the dirty ring documentation

   - Fix choice of target for directed yield across different calls to
     kvm_vcpu_on_spin(); the function was always starting from the first
     vCPU instead of continuing the round-robin search"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (260 commits)
  KVM: arm64: at: Update AF on software walk only if VM has FEAT_HAFDBS
  KVM: arm64: at: Use correct HA bit in TCR_EL2 when regime is EL2
  KVM: arm64: Document KVM_PGTABLE_PROT_{UX,PX}
  KVM: arm64: Fix spelling mistake "Unexpeced" -> "Unexpected"
  KVM: arm64: Add break to default case in kvm_pgtable_stage2_pte_prot()
  KVM: arm64: Add endian casting to kvm_swap_s[12]_desc()
  KVM: arm64: Fix compilation when CONFIG_ARM64_USE_LSE_ATOMICS=n
  KVM: arm64: selftests: Add test for AT emulation
  KVM: arm64: nv: Expose hardware access flag management to NV guests
  KVM: arm64: nv: Implement HW access flag management in stage-2 SW PTW
  KVM: arm64: Implement HW access flag management in stage-1 SW PTW
  KVM: arm64: Propagate PTW errors up to AT emulation
  KVM: arm64: Add helper for swapping guest descriptor
  KVM: arm64: nv: Use pgtable definitions in stage-2 walk
  KVM: arm64: Handle endianness in read helper for emulated PTW
  KVM: arm64: nv: Stop passing vCPU through void ptr in S2 PTW
  KVM: arm64: Call helper for reading descriptors directly
  KVM: arm64: nv: Advertise support for FEAT_XNX
  KVM: arm64: Teach ptdump about FEAT_XNX permissions
  KVM: s390: Use generic VIRT_XFER_TO_GUEST_WORK functions
  ...
2025-12-05 17:01:20 -08:00
Heiko Carstens d0139059e3 KVM: s390: Enable and disable interrupts in entry code
Move enabling and disabling of interrupts around the SIE instruction to
entry code. Enabling interrupts only after the __TI_sie flag has been set
guarantees that the SIE instruction is not executed if an interrupt happens
between enabling interrupts and the execution of the SIE instruction.
Interrupt handlers and machine check handler forward the PSW to the
sie_exit label in such cases.

This is a prerequisite for VIRT_XFER_TO_GUEST_WORK to prevent that guest
context is entered when e.g. a scheduler IPI, indicating that a reschedule
is required, happens right before the SIE instruction, which could lead to
long delays.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
2025-11-27 15:39:46 +01:00
Heiko Carstens 1c93edfd50 s390/entry: Use lay instead of aghik
Use the lay instruction instead of aghik. aghik is only available since
z196, therefore compiling the kernel for z10 results in this error:

   arch/s390/kernel/entry.S: Assembler messages:
   arch/s390/kernel/entry.S:165: Error: Unrecognized opcode: `aghik'

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202511261518.nBbQN5h7-lkp@intel.com/
Fixes: f5730d44e0 ("s390: Add stackprotector support")
Reviewed-by: Jan Polensky <japo@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-26 12:28:23 +01:00
Heiko Carstens f5730d44e0 s390: Add stackprotector support
Stackprotector support was previously unavailable on s390 because by
default compilers generate code which is not suitable for the kernel:
the canary value is accessed via thread local storage, where the address
of thread local storage is within access registers 0 and 1.

Using those registers also for the kernel would come with a significant
performance impact and more complicated kernel entry/exit code, since
access registers contents would have to be exchanged on every kernel entry
and exit.

With the upcoming gcc 16 release new compiler options will become available
which allow to generate code suitable for the kernel. [1]

Compiler option -mstack-protector-guard=global instructs gcc to generate
stackprotector code that refers to a global stackprotector canary value via
symbol __stack_chk_guard. Access to this value is guaranteed to occur via
larl and lgrl instructions.

Furthermore, compiler option -mstack-protector-guard-record generates a
section containing all code addresses that reference the canary value.

To allow for per task canary values the instructions which load the address
of __stack_chk_guard are patched so they access a lowcore field instead: a
per task canary value is available within the task_struct of each task, and
is written to the per-cpu lowcore location on each context switch.

Also add sanity checks and debugging option to be consistent with other
kernel code patching mechanisms.

Full debugging output can be enabled with the following kernel command line
options:

debug_stackprotector
bootdebug
ignore_loglevel
earlyprintk
dyndbg="file stackprotector.c +p"

Example debug output:

stackprot: 0000021e402d4eda: c010005a9ae3 -> c01f00070240

where "<insn address>: <old insn> -> <new insn>".

[1] gcc commit 0cd1f03939d5 ("s390: Support global stack protector")

Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-24 11:45:21 +01:00
Heiko Carstens 4ac286c4a8 s390/syscalls: Switch to generic system call table generation
The s390 syscall.tbl format differs slightly from most others, and
therefore requires an s390 specific system call table generation
script.

With compat support gone use the opportunity to switch to generic
system call table generation. The abi for all 64 bit system calls is
now common, since there is no need to specify if system call entry
points are only for 64 bit anymore.

Furthermore create the system call table in C instead of assembler
code in order to get type checking for all system call functions
contained within the table.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-17 11:10:39 +01:00
Heiko Carstens 8e0b986c59 s390: Remove compat support
There shouldn't be any 31 bit code around anymore that matters.
Remove the compat layer support required to run 31 bit code.

Reason for removal is code simplification and reduced test effort.

Note that this comes without any deprecation warnings added to config
options, or kernel messages, since most likely those would be ignored
anyway.

If it turns out there is still a reason to keep the compat layer this
can be reverted at any time in the future.

Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-11-17 11:10:38 +01:00
Kees Cook 57fbad15c2 stackleak: Rename STACKLEAK to KSTACK_ERASE
In preparation for adding Clang sanitizer coverage stack depth tracking
that can support stack depth callbacks:

- Add the new top-level CONFIG_KSTACK_ERASE option which will be
  implemented either with the stackleak GCC plugin, or with the Clang
  stack depth callback support.
- Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE,
  but keep it for anything specific to the GCC plugin itself.
- Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named
  for what it does rather than what it protects against), but leave as
  many of the internals alone as possible to avoid even more churn.

While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS,
since that's the only place it is referenced from.

Suggested-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-21 21:35:01 -07:00
Linus Torvalds d8cb068359 Merge tag 's390-6.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Heiko Carstens:

 - Large rework of the protected key crypto code to allow for
   asynchronous handling without memory allocation

 - Speed up system call entry/exit path by re-implementing lazy ASCE
   handling

 - Add module autoload support for the diag288_wdt watchdog device
   driver

 - Get rid of s390 specific strcpy() and strncpy() implementations, and
   switch all remaining users to strscpy() when possible

 - Various other small fixes and improvements

* tag 's390-6.16-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (51 commits)
  s390/pci: Serialize device addition and removal
  s390/pci: Allow re-add of a reserved but not yet removed device
  s390/pci: Prevent self deletion in disable_slot()
  s390/pci: Remove redundant bus removal and disable from zpci_release_device()
  s390/crypto: Extend protected key conversion retry loop
  s390/pci: Fix __pcilg_mio_inuser() inline assembly
  s390/ptrace: Always inline regs_get_kernel_stack_nth() and regs_get_register()
  s390/thread_info: Cleanup header includes
  s390/extmem: Add workaround for DCSS unload diag
  s390/crypto: Rework protected key AES for true asynch support
  s390/cpacf: Rework cpacf_pcc() to return condition code
  s390/mm: Fix potential use-after-free in __crst_table_upgrade()
  s390/mm: Add mmap_assert_write_locked() check to crst_table_upgrade()
  s390/string: Remove strcpy() implementation
  s390/con3270: Use strscpy() instead of strcpy()
  s390/boot: Use strspcy() instead of strcpy()
  s390: Simple strcpy() to strscpy() conversions
  s390/pkey/crypto: Introduce xflags param for pkey in-kernel API
  s390/pkey: Provide and pass xflags within pkey and zcrypt layers
  s390/uv: Remove uv_get_secret_metadata function
  ...
2025-05-26 14:36:05 -07:00
Heiko Carstens ae952eea6f s390/entry: Fix last breaking event handling in case of stack corruption
In case of stack corruption stack_invalid() is called and the expectation
is that register r10 contains the last breaking event address. This
dependency is quite subtle and broke a couple of years ago without that
anybody noticed.

Fix this by getting rid of the dependency and read the last breaking event
address from lowcore.

Fixes: 56e62a7370 ("s390: convert to generic entry")
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-05-05 15:46:34 +02:00
Heiko Carstens 8b72f5a97b s390/mm: Reimplement lazy ASCE handling
Reduce system call overhead time (round trip time for invoking a
non-existent system call) by 25%.

With the removal of set_fs() [1] lazy control register handling was removed
in order to keep kernel entry and exit simple. However this made system
calls slower.

With the conversion to generic entry [2] and numerous follow up changes
which simplified the entry code significantly, adding support for lazy asce
handling doesn't add much complexity to the entry code anymore.

In particular this means:

- On kernel entry the primary asce is not modified and contains the user
  asce

- Kernel accesses which require secondary-space mode (for example futex
  operations) are surrounded by enable_sacf_uaccess() and
  disable_sacf_uaccess() calls. enable_sacf_uaccess() sets the primary asce
  to kernel asce so that the sacf instruction can be used to switch to
  secondary-space mode. The primary asce is changed back to user asce with
  disable_sacf_uaccess().

The state of the control register which contains the primary asce is
reflected with a new TIF_ASCE_PRIMARY bit. This is required on context
switch so that the correct asce is restored for the scheduled in process.

In result address spaces are now setup like this:

CPU running in               | %cr1 ASCE | %cr7 ASCE | %cr13 ASCE
-----------------------------|-----------|-----------|-----------
user space                   |  user     |  user     |  kernel
kernel (no sacf)             |  user     |  user     |  kernel
kernel (during sacf uaccess) |  kernel   |  user     |  kernel
kernel (kvm guest execution) |  guest    |  user     |  kernel

In result cr1 control register content is not changed except for:
- futex system calls
- legacy s390 PCI system calls
- the kvm specific cmpxchg_user_key() uaccess helper

This leads to faster system call execution.

[1] 87d5986345 ("s390/mm: remove set_fs / rework address space handling")
[2] 56e62a7370 ("s390: convert to generic entry")

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-14 11:23:21 +02:00
Sven Schnelle 121df45b37 s390/entry: Fix setting _CIF_MCCK_GUEST with lowcore relocation
When lowcore relocation is enabled, the machine check handler doesn't
use the lowcore address when setting _CIF_MCCK_GUEST. Fix this by
adding the missing base register.

Fixes: 0001b7bbc5 ("s390/entry: Make mchk_int_handler() ready for lowcore relocation")
Reported-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2025-03-31 12:20:39 +02:00
Sven Schnelle f740a8b4df s390/traps: Change stack overflow message
When the kernel stack pointer is pointing to invalid memory,
a 'Kernel stack overflow' message is printed, which is misleading.
Change the message to actually say that the stack pointer is invalid
instead.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2025-03-04 17:34:03 +01:00
Heiko Carstens b337f6af67 s390: Use system header file variant of include directive
A few include directives use the local search variant even though the files
to be included aren't local. Therefore use the normal system header file
variant of the include directive.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2025-03-04 17:18:08 +01:00
Heiko Carstens e4da8249cf s390/lowcore: Convert relocated lowcore alternative to machine feature
Convert the explicit relocated lowcore alternative type to a more
generic machine feature. This only reduces the number of alternative
types, but has no impact on code generation.

Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2025-03-04 17:18:05 +01:00
Heiko Carstens 27939d6cde s390/Kconfig: Select VMAP_STACK unconditionally
There is no point in supporting !VMAP_STACK kernel builds. VMAP_STACK has
proven to work since many years. Also, since KASAN_VMALLOC is supported,
kernels built with !VMAP_STACK are completely untested.

Therefore select VMAP_STACK unconditionally and remove all config options
and code required for !VMAP_STACK builds.

Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-12-10 15:41:58 +01:00
Vasily Gorbik 45c9f2b856 s390/entry: Mark IRQ entries to fix stack depot warnings
The stack depot filters out everything outside of the top interrupt
context as an uninteresting or irrelevant part of the stack traces. This
helps with stack trace de-duplication, avoiding an explosion of saved
stack traces that share the same IRQ context code path but originate
from different randomly interrupted points, eventually exhausting the
stack depot.

Filtering uses in_irqentry_text() to identify functions within the
.irqentry.text and .softirqentry.text sections, which then become the
last stack trace entries being saved.

While __do_softirq() is placed into the .softirqentry.text section by
common code, populating .irqentry.text is architecture-specific.

Currently, the .irqentry.text section on s390 is empty, which prevents
stack depot filtering and de-duplication and could result in warnings
like:

Stack depot reached limit capacity
WARNING: CPU: 0 PID: 286113 at lib/stackdepot.c:252 depot_alloc_stack+0x39a/0x3c8

with PREEMPT and KASAN enabled.

Fix this by moving the IO/EXT interrupt handlers from .kprobes.text into
the .irqentry.text section and updating the kprobes blacklist to include
the .irqentry.text section.

This is done only for asynchronous interrupts and explicitly not for
program checks, which are synchronous and where the context beyond the
program check is important to preserve. Despite machine checks being
somewhat in between, they are extremely rare, and preserving context
when possible is also of value.

SVCs and Restart Interrupts are not relevant, one being always at the
boundary to user space and the other being a one-time thing.

IRQ entries filtering is also optionally used in ftrace function graph,
where the same logic applies.

Cc: stable@vger.kernel.org # 5.15+
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-11-21 12:44:07 +01:00
Claudio Imbrenda 05066cafa9 s390/mm/fault: Handle guest-related program interrupts in KVM
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 <imbrenda@linux.ibm.com>
Co-developed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-6-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-10-29 11:49:18 +01:00
Claudio Imbrenda f96cb0d61d s390/entry: Remove __GMAP_ASCE and use _PIF_GUEST_FAULT again
Now that the guest ASCE is passed as a parameter to __sie64a(),
_PIF_GUEST_FAULT can be used again to determine whether the fault was a
guest or host fault.

Since the guest ASCE will not be taken from the gmap pointer in lowcore
anymore, __GMAP_ASCE can be removed. For the same reason the guest
ASCE needs now to be saved into the cr1 save area unconditionally.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Acked-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lore.kernel.org/r/20241022120601.167009-2-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-10-29 11:49:18 +01:00
Linus Torvalds 1ec6d09789 Merge tag 's390-6.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Vasily Gorbik:

 - Optimize ftrace and kprobes code patching and avoid stop machine for
   kprobes if sequential instruction fetching facility is available

 - Add hiperdispatch feature to dynamically adjust CPU capacity in
   vertical polarization to improve scheduling efficiency and overall
   performance. Also add infrastructure for handling warning track
   interrupts (WTI), allowing for graceful CPU preemption

 - Rework crypto code pkey module and split it into separate,
   independent modules for sysfs, PCKMO, CCA, and EP11, allowing modules
   to load only when the relevant hardware is available

 - Add hardware acceleration for HMAC modes and the full AES-XTS cipher,
   utilizing message-security assist extensions (MSA) 10 and 11. It
   introduces new shash implementations for HMAC-SHA224/256/384/512 and
   registers the hardware-accelerated AES-XTS cipher as the preferred
   option. Also add clear key token support

 - Add MSA 10 and 11 processor activity instrumentation counters to perf
   and update PAI Extension 1 NNPA counters

 - Cleanup cpu sampling facility code and rework debug/WARN_ON_ONCE
   statements

 - Add support for SHA3 performance enhancements introduced with MSA 12

 - Add support for the query authentication information feature of MSA
   13 and introduce the KDSA CPACF instruction. Provide query and query
   authentication information in sysfs, enabling tools like cpacfinfo to
   present this data in a human-readable form

 - Update kernel disassembler instructions

 - Always enable EXPOLINE_EXTERN if supported by the compiler to ensure
   kpatch compatibility

 - Add missing warning handling and relocated lowcore support to the
   early program check handler

 - Optimize ftrace_return_address() and avoid calling unwinder

 - Make modules use kernel ftrace trampolines

 - Strip relocs from the final vmlinux ELF file to make it roughly 2
   times smaller

 - Dump register contents and call trace for early crashes to the
   console

 - Generate ptdump address marker array dynamically

 - Fix rcu_sched stalls that might occur when adding or removing large
   amounts of pages at once to or from the CMM balloon

 - Fix deadlock caused by recursive lock of the AP bus scan mutex

 - Unify sync and async register save areas in entry code

 - Cleanup debug prints in crypto code

 - Various cleanup and sanitizing patches for the decompressor

 - Various small ftrace cleanups

* tag 's390-6.12-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: (84 commits)
  s390/crypto: Display Query and Query Authentication Information in sysfs
  s390/crypto: Add Support for Query Authentication Information
  s390/crypto: Rework RRE and RRF CPACF inline functions
  s390/crypto: Add KDSA CPACF Instruction
  s390/disassembler: Remove duplicate instruction format RSY_RDRU
  s390/boot: Move boot_printk() code to own file
  s390/boot: Use boot_printk() instead of sclp_early_printk()
  s390/boot: Rename decompressor_printk() to boot_printk()
  s390/boot: Compile all files with the same march flag
  s390: Use MARCH_HAS_*_FEATURES defines
  s390: Provide MARCH_HAS_*_FEATURES defines
  s390/facility: Disable compile time optimization for decompressor code
  s390/boot: Increase minimum architecture to z10
  s390/als: Remove obsolete comment
  s390/sha3: Fix SHA3 selftests failures
  s390/pkey: Add AES xts and HMAC clear key token support
  s390/cpacf: Add MSA 10 and 11 new PCKMO functions
  s390/mm: Add cond_resched() to cmm_alloc/free_pages()
  s390/pai_ext: Update PAI extension 1 counters
  s390/pai_crypto: Add support for MSA 10 and 11 pai counters
  ...
2024-09-21 09:02:54 -07:00
Heiko Carstens 013e984397 s390/alternatives: Remove ALT_FACILITY_EARLY
Patch all alternatives which depend on facilities from the decompressor.
There is no technical reason which enforces to split patching of such
alternatives to the decompressor and the kernel.

This simplifies alternative handling a bit, since one alternative type is
removed.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2024-09-13 17:28:36 +02:00
Sven Schnelle ee3daf7c05 s390/entry: Unify save_area_sync and save_area_async
In the past two save areas existed because interrupt handlers
and system call / program check handlers where entered with
interrupts enabled. To prevent a handler from overwriting the
save areas from the previous handler, interrupts used the async
save area, while system call and program check handler used the
sync save area.

Since the removal of critical section cleanup from entry.S, handlers are
entered with interrupts disabled. When the interrupts are re-enabled,
the save area is no longer need. Therefore merge both save areas into one.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-08-29 22:56:34 +02:00
Heiko Carstens 85878ff1b3 s390/entry: Move early_pgm_check_handler() to init text section
Save some bytes and move early_pgm_check_handler() to init text
section.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-08-07 20:52:53 +02:00
Heiko Carstens f101b305a7 s390/entry: Make early program check handler relocated lowcore aware
Add the missing pieces so the early program check handler also works
with a relocated lowcore. Right now the result of an early program
check in case of a relocated lowcore would be a program check loop.

Fixes: 8f1e70adb1 ("s390/boot: Add cmdline option to relocate lowcore")
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-08-07 20:52:53 +02:00
Heiko Carstens f2bb5b97b5 s390/entry: Move early program check handler to entry.S
Have all program check handlers in one file to make future changes easy.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-08-07 20:52:53 +02:00
Sven Schnelle 361f6ec2fe s390/entry: Make system_call() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in system_call().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 9b3dcae128 s390/entry: Make ret_from_fork() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in ret_from_fork().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 7cc86dee44 s390/entry: Make __switch_to() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in __switch_to().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 4064b71112 s390/entry: Make restart_int_handler() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in restart_int_handler().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 0001b7bbc5 s390/entry: Make mchk_int_handler() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in mcck_int_handler().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle bd2c55b307 s390/entry: Make int handlers ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in the ext/io interrupt
handlers.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 9e1e275fa2 s390/entry: Make pgm_check_handler() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in pgm_check_handler().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 86e08d64ee s390/entry: Add base register to CHECK_VMAP_STACK/CHECK_STACK macro
In preparation of having lowcore at different address than zero,
add the base register to CHECK_VMAP_STACK and CHECK_STACK. No
functional change, because %r0 is passed to the macro.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 6908f8f916 s390/entry: Add base register to SIEEXIT macro
In preparation of having lowcore at different address than zero,
add the base register to SIEEXIT. No functional change, because
%r0 is passed to the macro.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle ca2f0a26c4 s390/entry: Add base register to MBEAR macro
In preparation of having lowcore at different address than zero,
add the base register to MBEAR. No functional change, because
%r0 is passed to the macro.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Sven Schnelle 12184a4676 s390/entry: Make __sie64a() ready for lowcore relocation
In preparation of having lowcore at different address than zero,
add the base register to all lowcore accesses in __sie64a().

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:32 +02:00
Heiko Carstens fc8eac33ad s390/entry: Move SIE indicator flag to thread info
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 <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Heiko Carstens 213400c4af s390/nmi: Simplify ptregs setup
The low level machine check handler code fills the ptregs structure
partially with the register contents present at machine check handler
entry and partially with contents from the machine check save area.

In case of a machine check the contents of all general purpose
registers are saved by the CPU to the machine check save area.
Therefore simplify the code and fill the ptregs structure by only
using the machine check save area as source.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Heiko Carstens 47837a5c74 s390/nospec: Push down alternative handling
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 <agordeev@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Heiko Carstens b3e0c5f734 s390/alternatives: Rework to allow for callbacks
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 <agordeev@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Heiko Carstens c77f7354c4 s390/alternatives: Merge both alternative header files
The two alternative header files must stay in sync. This is easier to
achieve within one header file. Therefore merge both of them and have
only one file, like most other architectures.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Sven Schnelle d3604ffba1 s390: Move CIF flags to struct pcpu
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 <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-23 16:02:31 +02:00
Claudio Imbrenda 723ac2d6ba s390/entry: Pass the asce as parameter to sie64a()
Pass the guest ASCE explicitly as parameter, instead of having sie64a()
take it from lowcore.

This removes hidden state from lowcore, and makes things look cleaner.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Nico Boehr <nrb@linux.ibm.com>
Link: https://lore.kernel.org/r/20240703155900.103783-2-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-07-10 19:50:45 +02:00
Sven Schnelle fa2ae4a377 s390/idle: Rewrite psw_idle() in C
To ease maintenance and further enhancements, convert
the psw_idle() function to C.

Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-05-14 13:37:07 +02:00
Sven Schnelle d111855ab7 s390/mm: Fix NULL pointer dereference
The recently added check to figure out if a fault happened on gmap ASCE
dereferences the gmap pointer in lowcore without checking that it is not
NULL. For all non-KVM processes the pointer is NULL, so that some value
from lowcore will be read. With the current layouts of struct gmap and
struct lowcore the read value (aka ASCE) is zero, so that this doesn't lead
to any observable bug; at least currently.

Fix this by adding the missing NULL pointer check.

Fixes: 64c3431808 ("s390/entry: compare gmap asce to determine guest/host fault")
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
2024-04-17 17:26:34 +02:00
Sumanth Korikkar 378ca2d2ad s390/entry: align system call table on 8 bytes
Align system call table on 8 bytes. With sys_call_table entry size
of 8 bytes that eliminates the possibility of a system call pointer
crossing cache line boundary.

Cc: stable@kernel.org
Suggested-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2024-04-03 15:00:20 +02:00
Sven Schnelle 64c3431808 s390/entry: compare gmap asce to determine guest/host fault
With the current implementation, there are some cornercases where
a host fault would be treated as a guest fault, for example
when the sie instruction causes a program check. Therefore store
the gmap asce in ptregs, and use that to compare the primary asce
from the fault instead of matching instruction addresses.

Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-03-17 19:08:50 +01:00
Sven Schnelle 29e5bc0f02 s390/entry: remove OUTSIDE macro
With only one OUTSIDE user left, remove the macro and move the code
directly to the machine check handler. This has the advantage that
it is much easier to determine which registers are used.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-03-17 19:08:49 +01:00
Sven Schnelle c239c83ed5 s390/entry: add CIF_SIE flag and remove sie64a() address check
When a program check, interrupt or machine check is triggered, the
PSW address is compared to a certain range of the sie64a() function
to figure out whether SIE was interrupted and a cleanup of SIE is
needed.

This doesn't work with kprobes: If kprobes probes an instruction, it
copies the instruction to the kprobes instruction page and overwrites the
original instruction with an undefind instruction (Opcode 00). When this
instruction is hit later, kprobes single-steps the instruction on the
kprobes_instruction page.

However, if this instruction is a relative branch instruction it will now
point to a different location in memory due to being moved to the kprobes
instruction page. If the new branch target points into sie64a() the kernel
assumes it interrupted SIE when processing the breakpoint and will crash
trying to access the SIE control block.

Instead of comparing the address, introduce a new CIF_SIE flag which
indicates whether SIE was interrupted.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-03-17 19:08:49 +01:00
Heiko Carstens ed3a0a011a s390/kvm: convert to regular kernel fpu user
KVM modifies the kernel fpu's regs pointer to its own area to implement its
custom version of preemtible kernel fpu context. With general support for
preemptible kernel fpu context there is no need for the extra complexity in
KVM code anymore.

Therefore convert KVM to a regular kernel fpu user. In particular this
means that all TIF_FPU checks can be removed, since the fpu register
context will never be changed by other kernel fpu users, and also the fpu
register context will be restored if a thread is preempted.

Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2024-02-16 14:30:16 +01:00