When userspace sends KVM_SET_LAPIC, KVM schedules a check between
the vCPU's IRR and ISR and the IOAPIC redirection table, in order
to re-establish the IOAPIC's dest_map (the list of CPUs servicing
the real-time clock interrupt with the corresponding vectors).

However, __rtc_irq_eoi_tracking_restore_one was forgetting to
set dest_map->vectors.  Because of this, the IOAPIC did not process
the real-time clock interrupt EOI, ioapic->rtc_status.pending_eoi
got stuck at a non-zero value, and further RTC interrupts were
reported to userspace as coalesced.

Fixes: 9e4aabe2
Fixes: 4d99ba89
Cc: stable@vger.kernel.org
Cc: Joerg Roedel <jroedel@suse.de>
Cc: David Gilbert <dgilbert@redhat.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Rename kvm_apic_get_reg to kvm_lapic_get_reg to be consistent with
the existing kvm_lapic_set_reg counterpart.
Signed-off-by: NSuravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Using the vector stored at interrupt delivery makes the eoi
matching safe agains irq migration in the ioapic.
Signed-off-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Currently this is a bitmap which tracks which CPUs we expect
an EOI from. Move this bitmap to a struct so that we can
track additional information there.
Signed-off-by: NJoerg Roedel <jroedel@suse.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The function to determine if the vector is handled by ioapic used to
rely on the fact that only ioapic-handled vectors were set up to
cause vmexits when virtual apic was in use.

We're going to break this assumption when introducing Hyper-V
synthetic interrupts: they may need to cause vmexits too.

To achieve that, introduce a new bitmap dedicated specifically for
ioapic-handled vectors, and populate EOI exit bitmap from it for now.
Signed-off-by: NAndrey Smetanin <asmetanin@virtuozzo.com>
Reviewed-by: NRoman Kagan <rkagan@virtuozzo.com>
Signed-off-by: NDenis V. Lunev <den@openvz.org>
CC: Gleb Natapov <gleb@kernel.org>
CC: Paolo Bonzini <pbonzini@redhat.com>
CC: Roman Kagan <rkagan@virtuozzo.com>
CC: Denis V. Lunev <den@openvz.org>
CC: qemu-devel@nongnu.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

KVM uses eoi_exit_bitmap to track vectors that need an action on EOI.
The problem is that IOAPIC can be reconfigured while an interrupt with
old configuration is pending and eoi_exit_bitmap only remembers the
newest configuration;  thus EOI from the pending interrupt is not
recognized.

(Reconfiguration is not a problem for level interrupts, because IOAPIC
 sends interrupt with the new configuration.)

For an edge interrupt with ACK notifiers, like i8254 timer; things can
happen in this order
 1) IOAPIC inject a vector from i8254
 2) guest reconfigures that vector's VCPU and therefore eoi_exit_bitmap
    on original VCPU gets cleared
 3) guest's handler for the vector does EOI
 4) KVM's EOI handler doesn't pass that vector to IOAPIC because it is
    not in that VCPU's eoi_exit_bitmap
 5) i8254 stops working

A simple solution is to set the IOAPIC vector in eoi_exit_bitmap if the
vector is in PIR/IRR/ISR.

This creates an unwanted situation if the vector is reused by a
non-IOAPIC source, but I think it is so rare that we don't want to make
the solution more sophisticated.  The simple solution also doesn't work
if we are reconfiguring the vector.  (Shouldn't happen in the wild and
I'd rather fix users of ACK notifiers instead of working around that.)

The are no races because ioapic injection and reconfig are locked.

Fixes: b053b2ae ("KVM: x86: Add EOI exit bitmap inference")
[Before b053b2ae, this bug happened only with APICv.]
Fixes: c7c9c56c ("x86, apicv: add virtual interrupt delivery support")
Cc: <stable@vger.kernel.org>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We can reuse the algorithm that computes the EOI exit bitmap to figure
out which vectors are handled by the IOAPIC.  The only difference
between the two is for edge-triggered interrupts other than IRQ8
that have no notifiers active; however, the IOAPIC does not have to
do anything special for these interrupts anyway.

This again limits the interactions between the IOAPIC and the LAPIC,
making it easier to move the former to userspace.

Inspired by a patch from Steve Rutherford.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Do not compute TMR in advance.  Instead, set the TMR just before the interrupt
is accepted into the IRR.  This limits the coupling between IOAPIC and LAPIC.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the null test is needed, the call to cancel_delayed_work_sync would have
already crashed.  Normally, the destroy function should only be called
if the init function has succeeded, in which case ioapic is not null.

Problem found using Coccinelle.
Suggested-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJulia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Extended struct kvm_lapic_irq with bool msi_redir_hint, which will
be used to determine if the delivery of the MSI should target only
the lowest priority CPU in the logical group specified for delivery.
(In physical dest mode, the RH bit is not relevant). Initialized the value
of msi_redir_hint to true when RH=1 in kvm_set_msi_irq(), and initialized
to false in all other cases.

Added value of msi_redir_hint to a debug message dump of an IRQ in
apic_send_ipi().
Signed-off-by: NJames Sullivan <sullivan.james.f@gmail.com>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This is needed in e.g. ARM vGIC emulation, where the MMIO handling
depends on the VCPU that does the access.
Signed-off-by: NNikolay Nikolaev <n.nikolaev@virtualopensystems.com>
Signed-off-by: NAndre Przywara <andre.przywara@arm.com>
Acked-by: NPaolo Bonzini <pbonzini@redhat.com>
Acked-by: NChristoffer Dall <christoffer.dall@linaro.org>
Reviewed-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>

An overhead from function call is not appropriate for its size and
frequency of execution.
Suggested-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

kvm_ioapic_update_eoi() wasn't called if directed EOI was enabled.
We need to do that for irq notifiers.  (Like with edge interrupts.)

Fix it by skipping EOI broadcast only.

Bug: https://bugzilla.kernel.org/show_bug.cgi?id=82211Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Tested-by: NBandan Das <bsd@redhat.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>

Signed-off-by: NRadim Krcmar <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

ia64 does not need them anymore.  Ack notifiers become x86-specific
too.
Suggested-by: NGleb Natapov <gleb@kernel.org>
Reviewed-by: NRadim Krcmar <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

KVM for ia64 has been marked as broken not just once, but twice even,
and the last patch from the maintainer is now roughly 5 years old.
Time for it to rest in peace.
Acked-by: NGleb Natapov <gleb@kernel.org>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Currently, we call ioapic_service() immediately when we find the irq is still
active during eoi broadcast. But for real hardware, there's some delay between
the EOI writing and irq delivery.  If we do not emulate this behavior, and
re-inject the interrupt immediately after the guest sends an EOI and re-enables
interrupts, a guest might spend all its time in the ISR if it has a broken
handler for a level-triggered interrupt.

Such livelock actually happens with Windows guests when resuming from
hibernation.

As there's no way to recognize the broken handle from new raised ones, this patch
delays an interrupt if 10.000 consecutive EOIs found that the interrupt was
still high.  The guest can then make a little forward progress, until a proper
IRQ handler is set or until some detection routine in the guest (such as
Linux's note_interrupt()) recognizes the situation.

Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: NJason Wang <jasowang@redhat.com>
Signed-off-by: NZhang Haoyu <zhanghy@sangfor.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

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>

The RTC tracking code tracks the cardinality of rtc_status.dest_map
into rtc_status.pending_eoi.  It has some WARN_ONs that trigger if
pending_eoi ever becomes negative; however, these do not do anything
to recover, and it bad things will happen soon after they trigger.

When the next RTC interrupt is triggered, rtc_check_coalesced() will
return false, but ioapic_service will find pending_eoi != 0 and
do a BUG_ON.  To avoid this, should pending_eoi ever be nonzero,
call kvm_rtc_eoi_tracking_restore_all to recompute a correct
dest_map and pending_eoi.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

QE reported that they got the BUG_ON in ioapic_service to trigger.
I cannot reproduce it, but there are two reasons why this could happen.

The less likely but also easiest one, is when kvm_irq_delivery_to_apic
does not deliver to any APIC and returns -1.

Because irqe.shorthand == 0, the kvm_for_each_vcpu loop in that
function is never reached.  However, you can target the similar loop in
kvm_irq_delivery_to_apic_fast; just program a zero logical destination
address into the IOAPIC, or an out-of-range physical destination address.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

After the previous patches, an interrupt whose bit is set in the IRR
register will never be in the LAPIC's IRR and has never been injected
on the migration source.  So inject it on the destination.

This fixes migration of Windows guests without HPET (they use the RTC
to trigger the scheduler tick, and lose it after migration).
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We will reuse it to process a nonzero IRR that is passed to KVM_SET_IRQCHIP.
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This ensures that IRR bits are set in the KVM_GET_IRQCHIP result only if
the interrupt is still sitting in the IOAPIC.  After the next patches, it
avoids spurious reinjection of the interrupt when KVM_SET_IRQCHIP is
called.
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commonize the handling of masking, which was absent for kvm_ioapic_set_irq.
Setting remote_irr does not need a separate function either, and merging
the two functions avoids confusion.
Reviewed-by: NAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Both QEMU and KVM have already accumulated a significant number of
optimizations based on the hard-coded assumption that ioapic polarity
will always use the ActiveHigh convention, where the logical and
physical states of level-triggered irq lines always match (i.e.,
active(asserted) == high == 1, inactive == low == 0). QEMU guests
are expected to follow directions given via ACPI and configure the
ioapic with polarity 0 (ActiveHigh). However, even when misbehaving
guests (e.g. OS X <= 10.9) set the ioapic polarity to 1 (ActiveLow),
QEMU will still use the ActiveHigh signaling convention when
interfacing with KVM.

This patch modifies KVM to completely ignore ioapic polarity as set by
the guest OS, enabling misbehaving guests to work alongside those which
comply with the ActiveHigh polarity specified by QEMU's ACPI tables.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NGabriel L. Somlo <somlo@cmu.edu>
[Move documentation to KVM_IRQ_LINE, add ia64. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Running 'make namespacecheck' found lots of functions that
should be declared static, since only used in one file.
Signed-off-by: NStephen Hemminger <stephen@networkplumber.org>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

We already know the trigger mode of a given interrupt when programming
the ioapice entry. So it's not necessary to set it in each interrupt
delivery.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Both TMR and EOI exit bitmap need to be updated when ioapic changed
or vcpu's id/ldr/dfr changed. So use common function instead eoi exit
bitmap specific function.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Current interrupt coalescing logci which only used by RTC has conflict
with Posted Interrupt.
This patch introduces a new mechinism to use eoi to track interrupt:
When delivering an interrupt to vcpu, the pending_eoi set to number of
vcpu that received the interrupt. And decrease it when each vcpu writing
eoi. No subsequent RTC interrupt can deliver to vcpu until all vcpus
write eoi.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Userspace may deliver RTC interrupt without query the status. So we
want to track RTC EOI for this case.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Need the EOI to track interrupt deliver status, so force vmexit
on EOI for rtc interrupt when enabling virtual interrupt delivery.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

restore rtc_status from migration or save/restore
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Add a new parameter to know vcpus who received the interrupt.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Add vcpu info to ioapic_update_eoi, so we can know which vcpu
issued this EOI.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Reviewed-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

For a given vcpu, kvm_apic_match_dest() will tell you whether
the vcpu in the destination list quickly. Drop kvm_calculate_eoi_exitmap()
and use kvm_apic_match_dest() instead.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

If the guest specifies a IOAPIC_REG_SELECT with an invalid value and follows
that with a read of the IOAPIC_REG_WINDOW KVM does not properly validate
that request.  ioapic_read_indirect contains an
ASSERT(redir_index < IOAPIC_NUM_PINS), but the ASSERT has no effect in
non-debug builds.  In recent kernels this allows a guest to cause a kernel
oops by reading invalid memory.  In older kernels (pre-3.3) this allows a
guest to read from large ranges of host memory.

Tested: tested against apic unit tests.
Signed-off-by: NAndrew Honig <ahonig@google.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Virtual interrupt delivery avoids KVM to inject vAPIC interrupts
manually, which is fully taken care of by the hardware. This needs
some special awareness into existing interrupr injection path:

- for pending interrupt, instead of direct injection, we may need
  update architecture specific indicators before resuming to guest.

- A pending interrupt, which is masked by ISR, should be also
  considered in above update action, since hardware will decide
  when to inject it at right time. Current has_interrupt and
  get_interrupt only returns a valid vector from injection p.o.v.
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NKevin Tian <kevin.tian@intel.com>
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

This hack is wrong. The pin number of PIT is connected to
2 not 0. This means this hack never takes effect. So it is ok
to remove it.
Signed-off-by: NYang Zhang <yang.z.zhang@Intel.com>
Signed-off-by: NGleb Natapov <gleb@redhat.com>

We validate irq pin number when routing is setup, so
code handling illegal irq # in pic and ioapic on each injection
is never called.
Drop it, replace with BUG_ON to catch out of bounds access bugs.
Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>