Another patch in my war on emulate_on_interception() use as a svm exit handler.

These were pulled out of a larger patch at the suggestion of Radim Krcmar, see
https://lkml.org/lkml/2015/2/25/559

Changes since v1:
	* fixed typo introduced after test, retested
Signed-off-by: NDavid Kaplan <david.kaplan@amd.com>
[separated out just cr_interception part from larger removal of
INTERCEPT_CR0_WRITE, forward ported, tested]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

No need to re-decode WBINVD since we know what it is from the intercept.
Signed-off-by: NDavid Kaplan <David.Kaplan@amd.com>
[extracted from larger unlrelated patch, forward ported, tested,style cleanup]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently kvm_emulate() skips the instruction but kvm_emulate_* sometimes
don't.  The end reult is the caller ends up doing the skip themselves.
Let's make them consistant.
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

kvm_kvfree() provides exactly the same functionality as the
new common kvfree() function - so let's simply replace the
kvm function with the common function.
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch fixes the bug discussed in
https://www.mail-archive.com/kvm@vger.kernel.org/msg109813.html

This patch uses a new field named irr_delivered to record the
delivery status of edge-triggered interrupts, and clears the
delivered interrupts in kvm_get_ioapic. So it has the same effect
of commit 0bc830b0
("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
while avoids the bug of Windows guests.
Signed-off-by: NWincy Van <fanwenyi0529@gmail.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

KVM has nice wrappers to access the register values, clean up a few places
that should use them but currently do not.
Signed-off-by: NDavid Kaplan <david.kaplan@amd.com>
[forward port and testing]
Signed-off-by: NJoel Schopp <joel.schopp@amd.com>
Acked-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

We finally have all the pieces in place, so let's include the
vector facility bit in the mask of available hardware facilities
for the guest to recognize.  Also, enable the vector functionality
in the guest control blocks, to avoid a possible vector data
exception that would otherwise occur when a vector instruction
is issued by the guest operating system.
Signed-off-by: NEric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Store additional status in the machine check handler, in order to
collect status (such as vector registers) that is not defined by
store status.
Signed-off-by: NEric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The new SIGP order Store Additional Status at Address is totally
handled by user space, but we should still record the occurrence
of this order in the kernel code.
Signed-off-by: NEric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

A new exception type for vector instructions is introduced with
the new processor, but is handled exactly like a Data Exception
which is already handled by the system.
Signed-off-by: NEric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Define and allocate space for both the host and guest views of
the vector registers for a given vcpu.  The 32 vector registers
occupy 128 bits each (512 bytes total), but architecturally are
paired with 512 additional bytes of reserved space for future
expansion.

The kvm_sync_regs structs containing the registers are union'ed
with 1024 bytes of padding in the common kvm_run struct.  The
addition of 1024 bytes of new register information clearly exceeds
the existing union, so an expansion of that padding is required.

When changing environments, we need to appropriately save and
restore the vector registers viewed by both the host and guest,
into and out of the sync_regs space.

The floating point registers overlay the upper half of vector
registers 0-15, so there's a bit of data duplication here that
needs to be carefully avoided.
Signed-off-by: NEric Farman <farman@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The guest debug functions work on absolute addresses and should use the
read_guest_abs() function rather than general read_guest() that
works with logical addresses.

Cc: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NAlexander Yarygin <yarygin@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

trace-cmd fails to parse the instruction interception trace point:
  "Error: expected type 5 but read 4
   failed to read event print fmt for kvm_s390_intercept_instruction"
The result is an unformatted string in the output, with a warning:
  "kvm_s390_intercept_instruction: [FAILED TO PARSE]..."

So let's add parentheses around the instruction parser macro to fix the format
parsing.
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Change 'architecuture' to 'architecture'
Signed-off-by: NYannick Guerrini <yguerrini@tomshardware.fr>
Message-Id: <1424989004-14412-1-git-send-email-yguerrini@tomshardware.fr>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The function kvm_s390_vcpu_setup_model() now performs all cpu model realated
setup tasks for a vcpu. Besides cpuid and ibc initialization, facility list
assignment takes place during the setup step as well. The model setup has been
pulled to the begin of vcpu setup to allow kvm facility tests.

There is no need to protect the cpu model setup with a lock since the attributes
can't be changed anymore as soon the first vcpu is online.
Signed-off-by: NMichael Mueller <mimu@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The common s390 function insn_length() results in slightly smaller
(and thus hopefully faster) code than the calculation of the
instruction length via a lookup-table. So let's use that function
in the interrupt delivery code, too.
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

When the SIE exited by a DAT access exceptions which we can not
resolve, the guest tried to access a page which is out of bounds
and can not be paged-in. In this case we have to signal the bad
access by injecting an address exception. However, address exceptions
are either suppressing or terminating, i.e. the PSW has to point to
the next instruction when the exception is delivered. Since the
originating DAT access exception is nullifying, the PSW still
points to the offending instruction instead, so we've got to forward
the PSW to the next instruction.
Having fixed this issue, we can now also enable the TPROT
interpretation facility again which had been disabled because
of this problem.
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

When certain program exceptions (e.g. DAT access exceptions) occur,
the current instruction has to be nullified, i.e. the old PSW that
gets written into the low-core has to point to the beginning of the
instruction again, and not to the beginning of the next instruction.
Thus we have to rewind the PSW before writing it into the low-core.
The list of nullifying exceptions can be found in the POP, chapter 6,
figure 6-1 ("Interruption Action").
Signed-off-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Reviewed-by: NJens Freimann <jfrei@linux.vnet.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The reinjection of an I/O interrupt can fail if the list is at the limit
and between the dequeue and the reinjection, another I/O interrupt is
injected (e.g. if user space floods kvm with I/O interrupts).

This patch avoids this memory leak and returns -EFAULT in this special
case. This error is not recoverable, so let's fail hard. This can later
be avoided by not dequeuing the interrupt but working directly on the
locked list.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

If the I/O interrupt could not be written to the guest provided
area (e.g. access exception), a program exception was injected into the
guest but "inti" wasn't freed, therefore resulting in a memory leak.

In addition, the I/O interrupt wasn't reinjected. Therefore the dequeued
interrupt is lost.

This patch fixes the problem while cleaning up the function and making the
cc and rc logic easier to handle.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

s390 documentation requires words 0 and 10-15 to be reserved and stored as
zeros. As we fill out all other fields, we can memset the full structure.
Signed-off-by: NEkaterina Tumanova <tumanova@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The set_memory_* functions currently only support module
addresses. The addresses are validated using is_module_addr.
That function is special though and relies on internal state
in the module subsystem to work properly. At the time of
module initialization and calling set_memory_*, it's too early
for is_module_addr to work properly so it always returns
false. Rather than be subject to the whims of the module state,
just bounds check against the module virtual address range.
Signed-off-by: NLaura Abbott <lauraa@codeaurora.org>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>

Commit:

  f31a9f7c ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area")

introduced alternative instructions for XSAVES/XRSTORS and commit:

  adb9d526 ("x86/xsaves: Add xsaves and xrstors support for booting time")

added support for the XSAVES/XRSTORS instructions at boot time.

Unfortunately both failed to properly protect them against faulting:

The 'xstate_fault' macro will use the closest label named '1'
backward and that ends up in the .altinstr_replacement section
rather than in .text. This means that the kernel will never find
in the __ex_table the .text address where this instruction might
fault, leading to serious problems if userspace manages to
trigger the fault.
Signed-off-by: NQuentin Casasnovas <quentin.casasnovas@oracle.com>
Signed-off-by: NJamie Iles <jamie.iles@oracle.com>
[ Improved the changelog, fixed some whitespace noise. ]
Acked-by: NBorislav Petkov <bp@alien8.de>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Cc: Allan Xavier <mr.a.xavier@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: adb9d526 ("x86/xsaves: Add xsaves and xrstors support for booting time")
Fixes: f31a9f7c ("x86/xsaves: Use xsaves/xrstors to save and restore xsave area")
Signed-off-by: NIngo Molnar <mingo@kernel.org>

The commit 8bbc2a13 ("x86/intel/quark: Add Intel Quark
platform support") introduced a minimal support of Intel Quark
SoC. That allows to use core parts of the SoC. However, the SPI,
I2C, and GPIO drivers can't be selected by kernel configuration
because they depend on COMMON_CLK. The patch adds a COMMON_CLK
selection to the platfrom definition to allow user choose the drivers.
Signed-off-by: NAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Acked-by: NOng, Boon Leong <boon.leong.ong@intel.com>
Cc: Bryan O'Donoghue <pure.logic@nexus-software.ie>
Cc: Darren Hart <dvhart@linux.intel.com>
Fixes: 8bbc2a13 ("x86/intel/quark: Add Intel Quark platform support")
Link: http://lkml.kernel.org/r/1425569044-2867-1-git-send-email-andriy.shevchenko@linux.intel.comSigned-off-by: NIngo Molnar <mingo@kernel.org>

I recently did a rework of the smc91x driver and did some build-testing
by compiling hundreds of randconfig kernels. Unfortunately, my script
was wrong and did not actually test the configurations that mattered,
so I introduced stupid typos in almost every file I touched.

I fixed my script now, built all configurations that actually matter
and fixed all the typos, this is the result.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Fixes: b70661c7 ("net: smc91x: use run-time configuration on all ARM machines")
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

'ret_from_fork' checks TIF_IA32 to determine whether 'pt_regs' and
the related state make sense for 'ret_from_sys_call'.  This is
entirely the wrong check.  TS_COMPAT would make a little more
sense, but there's really no point in keeping this optimization
at all.

This fixes a return to the wrong user CS if we came from int
0x80 in a 64-bit task.
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/4710be56d76ef994ddf59087aad98c000fbab9a4.1424989793.git.luto@amacapital.net
[ Backported from tip:x86/asm. ]
Signed-off-by: NIngo Molnar <mingo@kernel.org>

This patch fixes the backward compatibility of the older driver with the
newer firmware by making the binding unique so that the older driver won't
recognize the non-supported interfaces.

The new bindings are in sync with the newer firmware.
Signed-off-by: NIyappan Subramanian <isubramanian@apm.com>
Signed-off-by: NKeyur Chudgar <kchudgar@apm.com>
Tested-by: NMark Langsdorf <mlangsdo@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

When parsing resources for PCI host bridge, we should ignore resources
consumed by host bridge itself and only report window resources available
to child PCI busses.

Fixes: 593669c2 (x86/PCI/ACPI: Use common ACPI resource interfaces ...)
Signed-off-by: NJiang Liu <jiang.liu@linux.intel.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>

With patch "include guest facilities in kvm facility test" it is no
longer necessary to have special handling for the non-LPAR case.
Signed-off-by: NMichael Mueller <mimu@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Most facility related decisions in KVM have to take into account:

- the facilities offered by the underlying run container (LPAR/VM)
- the facilities supported by the KVM code itself
- the facilities requested by a guest VM

This patch adds the KVM driver requested facilities to the test routine.

It additionally renames struct s390_model_fac to kvm_s390_fac and its field
names to be more meaningful.

The semantics of the facilities stored in the KVM architecture structure
is changed. The address arch.model.fac->list now points to the guest
facility list and arch.model.fac->mask points to the KVM facility mask.

This patch fixes the behaviour of KVM for some facilities for guests
that ignore the guest visible facility bits, e.g. guests could use
transactional memory intructions on hosts supporting them even if the
chosen cpu model would not offer them.

The userspace interface is not affected by this change.
Signed-off-by: NMichael Mueller <mimu@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The facility lists were not fully copied.
Signed-off-by: NMichael Mueller <mimu@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Under z/VM PQAP might trigger an operation exception if no crypto cards
are defined via APVIRTUAL or APDEDICATED.

[  386.098666] Kernel BUG at 0000000000135c56 [verbose debug info unavailable]
[  386.098693] illegal operation: 0001 ilc:2 [#1] SMP
[...]
[  386.098751] Krnl PSW : 0704c00180000000 0000000000135c56 (kvm_s390_apxa_installed+0x46/0x98)
[...]
[  386.098804]  [<000000000013627c>] kvm_arch_init_vm+0x29c/0x358
[  386.098806]  [<000000000012d008>] kvm_dev_ioctl+0xc0/0x460
[  386.098809]  [<00000000002c639a>] do_vfs_ioctl+0x332/0x508
[  386.098811]  [<00000000002c660e>] SyS_ioctl+0x9e/0xb0
[  386.098814]  [<000000000070476a>] system_call+0xd6/0x258
[  386.098815]  [<000003fffc7400a2>] 0x3fffc7400a2

Lets add an extable entry and provide a zeroed config in that case.
Reported-by: NStefan Zimmermann <stzi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: NThomas Huth <thuth@linux.vnet.ibm.com>
Tested-by: NStefan Zimmermann <stzi@linux.vnet.ibm.com>

After d905c5df ("PPC: POWERNV: move iommu_add_device earlier"), the
refcnt on the kobject backing the IOMMU group for a PCI device is
elevated by each call to pci_dma_dev_setup_pSeriesLP() (via
set_iommu_table_base_and_group). When we go to dlpar a multi-function
PCI device out:

        iommu_reconfig_notifier ->
                iommu_free_table ->
                        iommu_group_put
                        BUG_ON(tbl->it_group)

We trip this BUG_ON, because there are still references on the table, so
it is not freed. Fix this by moving the powernv bus notifier to common
code and calling it for both powernv and pseries.

Fixes: d905c5df ("PPC: POWERNV: move iommu_add_device earlier")
Signed-off-by: NNishanth Aravamudan <nacc@linux.vnet.ibm.com>
Tested-by: NNishanth Aravamudan <nacc@linux.vnet.ibm.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

Anton has a busy ppc64le KVM box where guests sometimes hit the infamous
"kernel BUG at kernel/smpboot.c:134!" issue during boot:

  BUG_ON(td->cpu != smp_processor_id());

Basically a per CPU hotplug thread scheduled on the wrong CPU. The oops
output confirms it:

  CPU: 0
  Comm: watchdog/130

The problem is that we aren't ensuring the CPU active bit is set for the
secondary before allowing the master to continue on. The master unparks
the secondary CPU's kthreads and the scheduler looks for a CPU to run
on. It calls select_task_rq() and realises the suggested CPU is not in
the cpus_allowed mask. It then ends up in select_fallback_rq(), and
since the active bit isnt't set we choose some other CPU to run on.

This seems to have been introduced by 6acbfb96 "sched: Fix hotplug
vs. set_cpus_allowed_ptr()", which changed from setting active before
online to setting active after online. However that was in turn fixing a
bug where other code assumed an active CPU was also online, so we can't
just revert that fix.

The simplest fix is just to spin waiting for both active & online to be
set. We already have a barrier prior to set_cpu_online() (which also
sets active), to ensure all other setup is completed before online &
active are set.

Fixes: 6acbfb96 ("sched: Fix hotplug vs. set_cpus_allowed_ptr()")
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>

z/VM and LPAR enable key wrapping by default, lets do the same on KVM.
Signed-off-by: NTony Krowiak <akrowiak@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Enable disabled interrupt, on unsuccessful operation.

Found by Coccinelle.
Signed-off-by: NTapasweni Pathak <tapaswenipathak@gmail.com>
Acked-by: NJulia Lawall <julia.lawall@lip6.fr>
Reviewed-by: NJames Hogan <james.hogan@imgtec.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Currently the guest exit trace event saves the VCPU pointer to the
structure, and the guest PC is retrieved by dereferencing it when the
event is printed rather than directly from the trace record. This isn't
safe as the printing may occur long afterwards, after the PC has changed
and potentially after the VCPU has been freed. Usually this results in
the same (wrong) PC being printed for multiple trace events. It also
isn't portable as userland has no way to access the VCPU data structure
when interpreting the trace record itself.

Lets save the actual PC in the structure so that the correct value is
accessible later.

Fixes: 669e846e ("KVM/MIPS32: MIPS arch specific APIs for KVM")
Signed-off-by: NJames Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
Cc: <stable@vger.kernel.org> # v3.10+
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

In commit b4eef9b3, we started to use hwapic_isr_update() != NULL
instead of kvm_apic_vid_enabled(vcpu->kvm).  This didn't work because
SVM had it defined and "apicv" path in apic_{set,clear}_isr() does not
change apic->isr_count, because it should always be 1.  The initial
value of apic->isr_count was based on kvm_apic_vid_enabled(vcpu->kvm),
which is always 0 for SVM, so KVM could have injected interrupts when it
shouldn't.

Fix it by implicitly setting SVM's hwapic_isr_update to NULL and make the
initial isr_count depend on hwapic_isr_update() for good measure.

Fixes: b4eef9b3 ("kvm: x86: vmx: NULL out hwapic_isr_update() in case of !enable_apicv")
Reported-and-tested-by: NBorislav Petkov <bp@suse.de>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

The switch_mm function does nothing in case the prev and next mm
are the same. It can happen that a crst_table_downgrade has changed
the top-level pgd in the meantime on a different CPU. Always store
the new ASCE to be picked up in entry.S.

[heiko.carstens@de.ibm.com]: Bug was introduced with git commit
53e857f3 ("s390/mm,tlb: race of lazy TLB flush vs. recreation
of TLB entries") and causes random crashes due to broken page tables
being used.
Reported-by: NDominik Vogt <vogt@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>

With git commit 4d92f502 ("s390: reintroduce diag 44 calls for
cpu_relax()") I reintroduced a non-trivial cpu_relax() variant on s390.

The difference to the previous variant however is that the new version is
an out-of-line function, which will be traced if function tracing is enabled.

Switching to different tracers includes instruction patching. Therefore this
is done within stop_machine() "context" to prevent that any function tracing
is going on while instructions are being patched.
With the new out-of-line variant of cpu_relax() this is not true anymore,
since cpu_relax() gets called in a busy loop by all waiting cpus within
stop_machine() until function patching is finished.
Therefore cpu_relax() must be marked notrace.

This fixes kernel crashes when frequently switching between "function" and
"function_graph" tracers.

Moving cpu_relax() to a header file again, doesn't work because of header
include order dependencies.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>