Currently, the EOI exit bitmap (used for APICv) does not include
interrupts that are masked.  However, this can cause a bug that manifests
as an interrupt storm inside the guest.  Alex Williamson reported the
bug and is the one who really debugged this; I only wrote the patch. :)

The scenario involves a multi-function PCI device with OHCI and EHCI
USB functions and an audio function, all assigned to the guest, where
both USB functions use legacy INTx interrupts.

As soon as the guest boots, interrupts for these devices turn into an
interrupt storm in the guest; the host does not see the interrupt storm.
Basically the EOI path does not work, and the guest continues to see the
interrupt over and over, even after it attempts to mask it at the APIC.
The bug is only visible with older kernels (RHEL6.5, based on 2.6.32
with not many changes in the area of APIC/IOAPIC handling).

Alex then tried forcing bit 59 (corresponding to the USB functions' IRQ)
on in the eoi_exit_bitmap and TMR, and things then work.  What happens
is that VFIO asserts IRQ11, then KVM recomputes the EOI exit bitmap.
It does not have set bit 59 because the RTE was masked, so the IOAPIC
never sees the EOI and the interrupt continues to fire in the guest.

My guess was that the guest is masking the interrupt in the redirection
table in the interrupt routine, i.e. while the interrupt is set in a
LAPIC's ISR, The simplest fix is to ignore the masking state, we would
rather have an unnecessary exit rather than a missed IRQ ACK and anyway
IOAPIC interrupts are not as performance-sensitive as for example MSIs.
Alex tested this patch and it fixed his bug.

[Thanks to Alex for his precise description of the problem
 and initial debugging effort.  A lot of the text above is
 based on emails exchanged with him.]
Reported-by: NAlex Williamson <alex.williamson@redhat.com>
Tested-by: NAlex Williamson <alex.williamson@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Remove a prototype which was added by both 93c4adc7 and 36be0b9d.
Signed-off-by: NChris J Arges <chris.j.arges@canonical.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Resolve a shadow warning generated in W=2 builds by the nested
use of the min macro by instead using the min3 macro for the
minimum of 3 values.
Signed-off-by: NMark Rustad <mark.d.rustad@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Resolve missing-field-initializers warnings seen in W=2 kernel
builds by having macros generate more elaborated initializers.
That is enough to silence the warnings.
Signed-off-by: NMark Rustad <mark.d.rustad@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Using ARRAY_SIZE directly makes it easier to read the code.  While touching
the code, replace the division by a multiplication in the recently added
BUILD_BUG_ON.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Currently there is no check whether shared MSRs list overrun the allocated size
which can results in bugs. In addition there is no check that vmx->guest_msrs
has sufficient space to accommodate all the VMX msrs.  This patch adds the
assertions.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

x86 does not automatically set rflags.rf during event injection. This patch
does partial job, setting rflags.rf upon fault injection.  It does not handle
the setting of RF upon interrupt injection on rep-string instruction.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This patch updates RF for rep-string emulation.  The flag is set upon the first
iteration, and cleared after the last (if emulated). It is intended to make
sure that if a trap (in future data/io #DB emulation) or interrupt is delivered
to the guest during the rep-string instruction, RF will be set correctly. RF
affects whether instruction breakpoint in the guest is masked.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Merge tag 'kvm-s390-20140721' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-next

Bugfixes
--------
- add IPTE to trace event decoder
- document and advertise KVM_CAP_S390_IRQCHIP

Cleanups
--------
- Reuse kvm_vcpu_block for s390
- Get rid of tasklet for wakup processing

Haswell and newer Intel CPUs have support for RTM, and in that case DR6.RTM is
not fixed to 1 and DR7.RTM is not fixed to zero. That is not the case in the
current KVM implementation. This bug is apparent only if the MOV-DR instruction
is emulated or the host also debugs the guest.

This patch is a partial fix which enables DR6.RTM and DR7.RTM to be cleared and
set respectively. It also sets DR6.RTM upon every debug exception. Obviously,
it is not a complete fix, as debugging of RTM is still unsupported.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Make nested_release_vmcs12 idempotent.
Tested-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

free_nested needs the loaded_vmcs to be valid if it is a vmcs02, in
order to detach it from the shadow vmcs.  However, this is not
available anymore after commit 26a865f4 (KVM: VMX: fix use after
free of vmx->loaded_vmcs, 2014-01-03).

Revert that patch, and fix its problem by forcing a vmcs01 as the
active VMCS before freeing all the nested VMX state.
Reported-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Tested-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Defining XE, XM and VE vector numbers.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the RFLAGS.RF is set, then no #DB should occur on instruction breakpoints.
However, the KVM emulator injects #DB regardless to RFLAGS.RF. This patch fixes
this behavior. KVM, however, still appears not to update RFLAGS.RF correctly,
regardless of this patch.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

RFLAGS.RF was cleaned in several functions (e.g., syscall) in the x86 emulator.
Now that we clear it before the execution of an instruction in the emulator, we
can remove the specific cleanup of RFLAGS.RF.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When an instruction is emulated RFLAGS.RF should be cleared. KVM previously did
not do so. This patch clears RFLAGS.RF after interception is done.  If a fault
occurs during the instruction, RFLAGS.RF will be set by a previous patch.  This
patch does not handle the case of traps/interrupts during rep-strings. Traps
are only expected to occur on debug watchpoints, and those are anyhow not
handled by the emulator.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

RFLAGS.RF is always zero after popf. Therefore, popf should not updated RF, as
anyhow emulating popf, just as any other instruction should clear RFLAGS.RF.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When skipping an emulated instruction, rflags.rf should be cleared as it would
be on real x86 CPU.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Merge tag 'kvm-s390-20140715' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into kvm-next

This series enables the "KVM_(S|G)ET_MP_STATE" ioctls on s390 to make
the cpu state settable by user space.

This is necessary to avoid races in s390 SIGP/reset handling which
happen because some SIGPs are handled in QEMU, while others are
handled in the kernel. Together with the busy conditions as return
value of SIGP races happen especially in areas like starting and
stopping of CPUs. (For example, there is a program 'cpuplugd', that
runs on several s390 distros which does automatic onlining and
offlining on cpus.)

As soon as the MPSTATE interface is used, user space takes complete
control of the cpu states. Otherwise the kernel will use the old way.

Therefore, the new kernel continues to work fine with old QEMUs.

IPTE intercept can happen, let's decode that.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>

We should advertise all capabilities, including those that can
be enabled.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's document that this is a capability that may be enabled per-vm.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Capabilities can be enabled on a vcpu or (since recently) on a vm. Document
this and note for the existing capabilites whether they are per-vcpu or
per-vm.
Signed-off-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

We can get rid of the tasklet used for waking up a VCPU in the hrtimer
code but wakeup the VCPU directly.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Let's move the vcpu wakeup code to a central point.

We should set the vcpu->preempted flag only if the target is actually sleeping
and before the real wakeup happens. Otherwise the preempted flag might be set,
when not necessary. This may result in immediate reschedules after schedule()
in some scenarios.

The wakeup code doesn't require the local_int.lock to be held.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

The start_stop_lock is no longer acquired when in atomic context, therefore we
can convert it into an ordinary spin_lock.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

local_int.lock is not used in a bottom-half handler anymore, therefore we can
turn it into an ordinary spin_lock at all occurrences.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

This patch cleans up the code in handle_wait by reusing the common code
function kvm_vcpu_block.

signal_pending(), kvm_cpu_has_pending_timer() and kvm_arch_vcpu_runnable() are
sufficient for checking if we need to wake-up that VCPU. kvm_vcpu_block
uses these functions, so no checks are lost.

The flag "timer_due" can be removed - kvm_cpu_has_pending_timer() tests whether
the timer is pending, thus the vcpu is correctly woken up.
Signed-off-by: NDavid Hildenbrand <dahi@linux.vnet.ibm.com>
Acked-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: NCornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

This patch fix bug reported in https://bugzilla.kernel.org/show_bug.cgi?id=73331,
after the patch http://www.spinics.net/lists/kvm/msg105230.html applied, there is
some progress and the L2 can boot up, however, slowly. The original idea of this
fix vid injection patch is from "Zhang, Yang Z" <yang.z.zhang@intel.com>.

Interrupt which delivered by vid should be injected to L1 by L0 if current is in
L1, or should be injected to L2 by L0 through the old injection way if L1 doesn't
have set External-interrupt exiting bit. The current logic doen't consider these
cases. This patch fix it by vid intr to L1 if current is L1 or L2 through old
injection way if L1 doen't have External-interrupt exiting bit set.
Signed-off-by: NWanpeng Li <wanpeng.li@linux.intel.com>
Signed-off-by: N"Zhang, Yang Z" <yang.z.zhang@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Certain instructions (e.g., mwait and monitor) cause a #UD exception when they
are executed in user mode. This is in contrast to the regular privileged
instructions which cause #GP. In order not to mess with SVM interception of
mwait and monitor which assumes privilege level assertions take place before
interception, a flag has been added.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Certain instructions, such as monitor and xsave do not support big real mode
and cause a #GP exception if any of the accessed bytes effective address are
not within [0, 0xffff].  This patch introduces a flag to mark these
instructions, including the necassary checks.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Emulator accesses are always done a page at a time, either by the emulator
itself (for fetches) or because we need to query the MMU for address
translations.  Speed up these accesses by using kvm_read_guest_page
and, in the case of fetches, by inlining kvm_read_guest_virt_helper and
dropping the loop around kvm_read_guest_page.

This final tweak saves 30-100 more clock cycles (4-10%), bringing the
count (as measured by kvm-unit-tests) down to 720-1100 clock cycles on
a Sandy Bridge Xeon host, compared to 2300-3200 before the whole series
and 925-1700 after the first two low-hanging fruit changes.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When the CS base is not page-aligned, the linear address of the code could
get close to the page boundary (e.g. 0x...ffe) even if the EIP value is
not.  So we need to first linearize the address, and only then compute
the number of valid bytes that can be fetched.

This happens relatively often when executing real mode code.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This simplifies the code a bit, especially the overflow checks.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We do not need a memory copying loop anymore in insn_fetch; we
can use a byte-aligned pointer to access instruction fields directly
from the fetch_cache.  This eliminates 50-150 cycles (corresponding to
a 5-10% improvement in performance) from each instruction.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

do_insn_fetch_bytes will only be called once in a given insn_fetch and
insn_fetch_arr, because in fact it will only be called at most twice
for any instruction and the first call is explicit in x86_decode_insn.
This observation lets us hoist the call out of the memory copying loop.
It does not buy performance, because most fetches are one byte long
anyway, but it prepares for the next patch.

The overflow check is tricky, but correct.  Because do_insn_fetch_bytes
has already been called once, we know that fc->end is at least 15.  So
it is okay to subtract the number of bytes we want to read.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hoist the common case up from do_insn_fetch_byte to do_insn_fetch,
and prime the fetch_cache in x86_decode_insn.  This helps a bit the
compiler and the branch predictor, but above all it lays the
ground for further changes in the next few patches.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

rip_relative is only set if decode_modrm runs, and if you have ModRM
you will also have a memopp.  We can then access memopp unconditionally.
Note that rip_relative cannot be hoisted up to decode_modrm, or you
break "mov $0, xyz(%rip)".

Also, move typecast on "out of range value" of mem.ea to decode_modrm.

Together, all these optimizations save about 50 cycles on each emulated
instructions (4-6%).
Signed-off-by: NBandan Das <bsd@redhat.com>
[Fix immediate operands with rip-relative addressing. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

x86_decode_insn already sets a default for seg_override,
so remove it from the zeroed area. Also replace set/get functions
with direct access to the field.
Signed-off-by: NBandan Das <bsd@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

A lot of initializations are unnecessary as they get set to
appropriate values before actually being used. Optimize
placement of fields in x86_emulate_ctxt
Signed-off-by: NBandan Das <bsd@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>