linux.git/arch/s390, branch v4.16

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2018-03-10T00:59:19+00:00

Pull KVM fixes from Radim Krčmář:
 "PPC:

   - Fix guest time accounting in the host

   - Fix large-page backing for radix guests on POWER9

   - Fix HPT guests on POWER9 backed by 2M or 1G pages

   - Compile fixes for some configs and gcc versions

  s390:

   - Fix random memory corruption when running as guest2 (e.g. KVM in
     LPAR) and starting guest3 (e.g. nested KVM) with many CPUs

   - Export forgotten io interrupt delivery statistics counter"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: s390: fix memory overwrites when not using SCA entries
  KVM: PPC: Book3S HV: Fix guest time accounting with VIRT_CPU_ACCOUNTING_GEN
  KVM: PPC: Book3S HV: Fix VRMA initialization with 2MB or 1GB memory backing
  KVM: PPC: Book3S HV: Fix handling of large pages in radix page fault handler
  KVM: s390: provide io interrupt kvm_stat
  KVM: PPC: Book3S: Fix compile error that occurs with some gcc versions
  KVM: PPC: Fix compile error that occurs when CONFIG_ALTIVEC=n

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2018-03-07T18:59:23+00:00

Pull s390 fixes from Martin Schwidefsky:
 "Nine bug fixes for s390:

   - Three fixes for the expoline code, one of them is strictly speaking
     a cleanup but as it relates to code added with 4.16 I would like to
     include the patch.

   - Three timer related fixes in the common I/O layer

   - A fix for the handling of internal DASD request which could cause
     panics.

   - One correction in regard to the accounting of pud page tables vs.
     compat tasks.

   - The register scrubbing in entry.S caused spurious crashes, this is
     fixed now as well"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390/entry.S: fix spurious zeroing of r0
  s390: Fix runtime warning about negative pgtables_bytes
  s390: do not bypass BPENTER for interrupt system calls
  s390/cio: clear timer when terminating driver I/O
  s390/cio: fix return code after missing interrupt
  s390/cio: fix ccw_device_start_timeout API
  s390/clean-up: use CFI_* macros in entry.S
  s390: Replace IS_ENABLED(EXPOLINE_*) with IS_ENABLED(CONFIG_EXPOLINE_*)
  s390/dasd: fix handling of internal requests

KVM: s390: fix memory overwrites when not using SCA entries

2018-03-06T13:33:02+00:00

Even if we don't have extended SCA support, we can have more than 64 CPUs
if we don't enable any HW features that might use the SCA entries.

Now, this works just fine, but we missed a return, which is why we
would actually store the SCA entries. If we have more than 64 CPUs, this
means writing outside of the basic SCA - bad.

Let's fix this. This allows > 64 CPUs when running nested (under vSIE)
without random crashes.

Fixes: a6940674c384 ("KVM: s390: allow 255 VCPUs when sca entries aren't used")
Reported-by: Christian Borntraeger 
Tested-by: Christian Borntraeger 
Signed-off-by: David Hildenbrand 
Message-Id: <20180306132758.21034-1-david@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Cornelia Huck 
Signed-off-by: Christian Borntraeger

s390/entry.S: fix spurious zeroing of r0

2018-03-06T08:19:35+00:00

when a system call is interrupted we might call the critical section
cleanup handler that re-does some of the operations. When we are between
.Lsysc_vtime and .Lsysc_do_svc we might also redo the saving of the
problem state registers r0-r7:

.Lcleanup_system_call:
[...]
0:      # update accounting time stamp
        mvc     __LC_LAST_UPDATE_TIMER(8),__LC_SYNC_ENTER_TIMER
        # set up saved register r11
        lg      %r15,__LC_KERNEL_STACK
        la      %r9,STACK_FRAME_OVERHEAD(%r15)
        stg     %r9,24(%r11)            # r11 pt_regs pointer
        # fill pt_regs
        mvc     __PT_R8(64,%r9),__LC_SAVE_AREA_SYNC
--->    stmg    %r0,%r7,__PT_R0(%r9)

The problem is now, that we might have already zeroed out r0.
The fix is to move the zeroing of r0 after sysc_do_svc.

Reported-by: Farhan Ali 
Fixes: 7041d28115e91 ("s390: scrub registers on kernel entry and KVM exit")
Signed-off-by: Christian Borntraeger 
Signed-off-by: Martin Schwidefsky

s390: Fix runtime warning about negative pgtables_bytes

2018-03-02T11:48:40+00:00

When running s390 images with 'compat' processes, the following
BUG is seen repeatedly.

BUG: non-zero pgtables_bytes on freeing mm: -16384

Bisect points to commit b4e98d9ac775 ("mm: account pud page tables").
Analysis shows that init_new_context() is called with
mm->context.asce_limit set to _REGION3_SIZE. In this situation,
pgtables_bytes remains set to 0 and is not increased. The message is
displayed when the affected process dies and mm_dec_nr_puds() is called.

Cc: Kirill A. Shutemov 
Cc: Heiko Carstens 
Fixes: b4e98d9ac775 ("mm: account pud page tables")
Signed-off-by: Guenter Roeck 
Signed-off-by: Martin Schwidefsky

KVM: s390: provide io interrupt kvm_stat

2018-03-01T12:10:32+00:00

We already count io interrupts, but we forgot to print them.

Signed-off-by: Christian Borntraeger 
Fixes: d8346b7d9b ("KVM: s390: Support for I/O interrupts.")
Reviewed-by: Cornelia Huck 
Reviewed-by: David Hildenbrand 
Signed-off-by: Christian Borntraeger

s390: do not bypass BPENTER for interrupt system calls

2018-02-22T13:08:51+00:00

The system call path can be interrupted before the switch back to the
standard branch prediction with BPENTER has been done. The critical
section cleanup code skips forward to .Lsysc_do_svc and bypasses the
BPENTER. In this case the kernel and all subsequent code will run with
the limited branch prediction.

Fixes: eacf67eb9b32 ("s390: run user space and KVM guests with modified branch prediction")
Signed-off-by: Martin Schwidefsky

s390/clean-up: use CFI_* macros in entry.S

2018-02-22T09:09:20+00:00

Commit f19fbd5ed642 ("s390: introduce execute-trampolines for
branches") introduces .cfi_* assembler directives.  Instead of
using the directives directly, use the macros from asm/dwarf.h.
This also ensures that the dwarf debug information are created
in the .debug_frame section.

Fixes: f19fbd5ed642 ("s390: introduce execute-trampolines for branches")
Signed-off-by: Hendrik Brueckner 
Signed-off-by: Martin Schwidefsky

KVM: s390: provide only a single function for setting the tod (fix SCK)

2018-02-20T20:51:28+00:00

Right now, SET CLOCK called in the guest does not properly take care of
the epoch index, as the call goes via the old kvm_s390_set_tod_clock()
interface. So the epoch index is neither reset to 0, if required, nor
properly set to e.g. 0xff on negative values.

Fix this by providing a single kvm_s390_set_tod_clock() function. Move
Multiple-epoch facility handling into it.

Signed-off-by: David Hildenbrand 
Message-Id: <20180207114647.6220-3-david@redhat.com>
Reviewed-by: Christian Borntraeger 
Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger

KVM: s390: consider epoch index on TOD clock syncs

2018-02-20T20:51:21+00:00

For now, we don't take care of over/underflows. Especially underflows
are critical:

Assume the epoch is currently 0 and we get a sync request for delta=1,
meaning the TOD is moved forward by 1 and we have to fix it up by
subtracting 1 from the epoch. Right now, this will leave the epoch
index untouched, resulting in epoch=-1, epoch_idx=0, which is wrong.

We have to take care of over and underflows, also for the VSIE case. So
let's factor out calculation into a separate function.

Signed-off-by: David Hildenbrand 
Message-Id: <20180207114647.6220-5-david@redhat.com>
Reviewed-by: Christian Borntraeger 
Fixes: 8fa1696ea781 ("KVM: s390: Multiple Epoch Facility support")
Cc: stable@vger.kernel.org
Signed-off-by: Christian Borntraeger 
[use u8 for idx]