Commit Graph

19 Commits

Author SHA1 Message Date
Carsten Otte
e52b2af541 KVM: s390: Fix race condition in kvm_s390_handle_wait
The call to add_timer was issued before local_int.lock was taken and before
timer_due was set to 0. If the timer expires before the lock is being taken,
the timer function will set timer_due to 1 and exit before the vcpu falls
asleep. Depending on other external events, the vcpu might sleep forever.
This fix pulls setting timer_due to the beginning of the function before
add_timer, which ensures correct behavior.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06 21:08:26 +03:00
Carsten Otte
1f0d0f094d KVM: s390: Send program check on access error
If the guest accesses non-existing memory, the sie64a function returns
-EFAULT. We must check the return value and send a program check to the
guest if the sie instruction faulted, otherwise the guest will loop at
the faulting code.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06 21:08:26 +03:00
Carsten Otte
0ff3186745 KVM: s390: fix interrupt delivery
The current code delivers pending interrupts before it checks for
need_resched. On a busy host, this can lead to a longer interrupt
latency if the interrupt is injected while the process is scheduled
away. This patch moves delivering the interrupt _after_ schedule(),
which makes more sense.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06 21:08:26 +03:00
Christian Borntraeger
71cde5879f KVM: s390: handle machine checks when guest is running
The low-level interrupt handler on s390 checks for _TIF_WORK_INT and
exits the guest context, if work is pending.
TIF_WORK_INT is defined as_TIF_SIGPENDING | _TIF_NEED_RESCHED |
 _TIF_MCCK_PENDING. Currently the sie loop checks for signals and
reschedule, but it does not check for machine checks. That means that
we exit the guest context if a machine check is pending, but we do not
handle the machine check.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06 21:08:26 +03:00
Christian Borntraeger
b8cee18cc7 KVM: s390: use yield instead of schedule to implement diag 0x44
diag 0x44 is the common way on s390 to yield the cpu to the hypervisor.
It is called by the guest in cpu_relax and in the spinlock code to
yield to other guest cpus.

This semantic is similar to yield. Lets replace the call to schedule with
yield to make sure that current is really yielding.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-06-06 21:08:26 +03:00
Christian Borntraeger
0eaeafa10f [S390] s390-kvm: leave sie context on work. Removes preemption requirement
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

This patch fixes a bug with cpu bound guest on kvm-s390. Sometimes it
was impossible to deliver a signal to a spinning guest. We used
preemption as a circumvention. The preemption notifiers called
vcpu_load, which checked for pending signals and triggered a host
intercept. But even with preemption, a sigkill was not delivered
immediately.

This patch changes the low level host interrupt handler to check for the
SIE  instruction, if TIF_WORK is set. In that case we change the
instruction pointer of the return PSW to rerun the vcpu_run loop. The kvm
code sees an intercept reason 0 if that happens. This patch adds accounting
for these types of intercept as well.

The advantages:
- works with and without preemption
- signals are delivered immediately
- much better host latencies without preemption

Acked-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-05-07 09:23:01 +02:00
Heiko Carstens
484875b11f [S390] Move stfl to system.h and delete duplicated version.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2008-04-30 13:38:46 +02:00
Marcelo Tosatti
62d9f0dbc9 KVM: add ioctls to save/store mpstate
So userspace can save/restore the mpstate during migration.

[avi: export the #define constants describing the value]
[christian: add s390 stubs]
[avi: ditto for ia64]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 18:21:16 +03:00
Marcelo Tosatti
3d80840d96 KVM: hlt emulation should take in-kernel APIC/PIT timers into account
Timers that fire between guest hlt and vcpu_block's add_wait_queue() are
ignored, possibly resulting in hangs.

Also make sure that atomic_inc and waitqueue_active tests happen in the
specified order, otherwise the following race is open:

CPU0                                        CPU1
                                            if (waitqueue_active(wq))
add_wait_queue()
if (!atomic_read(pit_timer->pending))
    schedule()
                                            atomic_inc(pit_timer->pending)

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:04:11 +03:00
Avi Kivity
7732a8d19b KVM: s390: Stub out kvmtrace
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:01:20 +03:00
Heiko Carstens
f603f0731f KVM: s390: rename stfl to kvm_stfl
Temporarily rename this function to avoid merge conflicts and/or
dependencies. This function will be removed as soon as git-s390
and kvm.git are finally upstream.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:59 +03:00
Heiko Carstens
7e8e6ab48d KVM: s390: Fix incorrect return value
kvm_arch_vcpu_ioctl_run currently incorrectly always returns 0.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:58 +03:00
Christian Borntraeger
77b455f1bc KVM: s390: add kvm to kconfig on s390
This patch adds the virtualization submenu and the kvm option to the kernel
config. It also defines HAVE_KVM for 64bit kernels.

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:47 +03:00
Christian Borntraeger
e28acfea5d KVM: s390: intercepts for diagnose instructions
This patch introduces interpretation of some diagnose instruction intercepts.
Diagnose is our classic architected way of doing a hypercall. This patch
features the following diagnose codes:
- vm storage size, that tells the guest about its memory layout
- time slice end, which is used by the guest to indicate that it waits
  for a lock and thus cannot use up its time slice in a useful way
- ipl functions, which a guest can use to reset and reboot itself

In order to implement ipl functions, we also introduce an exit reason that
causes userspace to perform various resets on the virtual machine. All resets
are described in the principles of operation book, except KVM_S390_RESET_IPL
which causes a reboot of the machine.

Acked-by: Martin Schwidefsky <martin.schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:46 +03:00
Christian Borntraeger
5288fbf0ef KVM: s390: interprocessor communication via sigp
This patch introduces in-kernel handling of _some_ sigp interprocessor
signals (similar to ipi).
kvm_s390_handle_sigp() decodes the sigp instruction and calls individual
handlers depending on the operation requested:
- sigp sense tries to retrieve information such as existence or running state
  of the remote cpu
- sigp emergency sends an external interrupt to the remove cpu
- sigp stop stops a remove cpu
- sigp stop store status stops a remote cpu, and stores its entire internal
  state to the cpus lowcore
- sigp set arch sets the architecture mode of the remote cpu. setting to
  ESAME (s390x 64bit) is accepted, setting to ESA/S390 (s390, 31 or 24 bit) is
  denied, all others are passed to userland
- sigp set prefix sets the prefix register of a remote cpu

For implementation of this, the stop intercept indication starts to get reused
on purpose: a set of action bits defines what to do once a cpu gets stopped:
ACTION_STOP_ON_STOP  really stops the cpu when a stop intercept is recognized
ACTION_STORE_ON_STOP stores the cpu status to lowcore when a stop intercept is
                     recognized

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:46 +03:00
Christian Borntraeger
453423dce2 KVM: s390: intercepts for privileged instructions
This patch introduces in-kernel handling of some intercepts for privileged
instructions:

handle_set_prefix()        sets the prefix register of the local cpu
handle_store_prefix()      stores the content of the prefix register to memory
handle_store_cpu_address() stores the cpu number of the current cpu to memory
handle_skey()              just decrements the instruction address and retries
handle_stsch()             delivers condition code 3 "operation not supported"
handle_chsc()              same here
handle_stfl()              stores the facility list which contains the
                           capabilities of the cpu
handle_stidp()             stores cpu type/model/revision and such
handle_stsi()              stores information about the system topology

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:45 +03:00
Carsten Otte
ba5c1e9b6c KVM: s390: interrupt subsystem, cpu timer, waitpsw
This patch contains the s390 interrupt subsystem (similar to in kernel apic)
including timer interrupts (similar to in-kernel-pit) and enabled wait
(similar to in kernel hlt).

In order to achieve that, this patch also introduces intercept handling
for instruction intercepts, and it implements load control instructions.

This patch introduces an ioctl KVM_S390_INTERRUPT which is valid for both
the vm file descriptors and the vcpu file descriptors. In case this ioctl is
issued against a vm file descriptor, the interrupt is considered floating.
Floating interrupts may be delivered to any virtual cpu in the configuration.

The following interrupts are supported:
SIGP STOP       - interprocessor signal that stops a remote cpu
SIGP SET PREFIX - interprocessor signal that sets the prefix register of a
                  (stopped) remote cpu
INT EMERGENCY   - interprocessor interrupt, usually used to signal need_reshed
                  and for smp_call_function() in the guest.
PROGRAM INT     - exception during program execution such as page fault, illegal
                  instruction and friends
RESTART         - interprocessor signal that starts a stopped cpu
INT VIRTIO      - floating interrupt for virtio signalisation
INT SERVICE     - floating interrupt for signalisations from the system
                  service processor

struct kvm_s390_interrupt, which is submitted as ioctl parameter when injecting
an interrupt, also carrys parameter data for interrupts along with the interrupt
type. Interrupts on s390 usually have a state that represents the current
operation, or identifies which device has caused the interruption on s390.

kvm_s390_handle_wait() does handle waitpsw in two flavors: in case of a
disabled wait (that is, disabled for interrupts), we exit to userspace. In case
of an enabled wait we set up a timer that equals the cpu clock comparator value
and sleep on a wait queue.

[christian: change virtio interrupt to 0x2603]

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:44 +03:00
Christian Borntraeger
8f2abe6a1e KVM: s390: sie intercept handling
This path introduces handling of sie intercepts in three flavors: Intercepts
are either handled completely in-kernel by kvm_handle_sie_intercept(),
or passed to userspace with corresponding data in struct kvm_run in case
kvm_handle_sie_intercept() returns -ENOTSUPP.
In case of partial execution in kernel with the need of userspace support,
kvm_handle_sie_intercept() may choose to set up struct kvm_run and return
-EREMOTE.

The trivial intercept reasons are handled in this patch:
handle_noop() just does nothing for intercepts that don't require our support
  at all
handle_stop() is called when a cpu enters stopped state, and it drops out to
  userland after updating our vcpu state
handle_validity() faults in the cpu lowcore if needed, or passes the request
  to userland

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:43 +03:00
Heiko Carstens
b0c632db63 KVM: s390: arch backend for the kvm kernel module
This patch contains the port of Qumranet's kvm kernel module to IBM zSeries
 (aka s390x, mainframe) architecture. It uses the mainframe's virtualization
instruction SIE to run virtual machines with up to 64 virtual CPUs each.
This port is only usable on 64bit host kernels, and can only run 64bit guest
kernels. However, running 31bit applications in guest userspace is possible.

The following source files are introduced by this patch
arch/s390/kvm/kvm-s390.c    similar to arch/x86/kvm/x86.c, this implements all
                            arch callbacks for kvm. __vcpu_run calls back into
                            sie64a to enter the guest machine context
arch/s390/kvm/sie64a.S      assembler function sie64a, which enters guest
                            context via SIE, and switches world before and after                            that
include/asm-s390/kvm_host.h contains all vital data structures needed to run
                            virtual machines on the mainframe
include/asm-s390/kvm.h      defines kvm_regs and friends for user access to
                            guest register content
arch/s390/kvm/gaccess.h     functions similar to uaccess to access guest memory
arch/s390/kvm/kvm-s390.h    header file for kvm-s390 internals, extended by
                            later patches

Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-04-27 12:00:42 +03:00