According to SDM 27.2.3, IDT vectoring information will not be valid on
vmexits caused by external NMIs. So we have to avoid creating such
scenarios by delaying EXIT_REASON_EXCEPTION_NMI injection as long as we
have a pending interrupt because that one would be migrated to L1's IDT
vectoring info on nested exit.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We cannot rely on the hardware-provided preemption timer support because
we are holding L2 in HLT outside non-root mode. Furthermore, emulating
the preemption will resolve tick rate errata on older Intel CPUs.

The emulation is based on hrtimer which is started on L2 entry, stopped
on L2 exit and evaluated via the new check_nested_events hook. As we no
longer rely on hardware features, we can enable both the preemption
timer support and value saving unconditionally.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Move the check for leaving L2 on pending and intercepted IRQs or NMIs
from the *_allowed handler into a dedicated callback. Invoke this
callback at the relevant points before KVM checks if IRQs/NMIs can be
injected. The callback has the task to switch from L2 to L1 if needed
and inject the proper vmexit events.

The rework fixes L2 wakeups from HLT and provides the foundation for
preemption timer emulation.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

commit 0061d53d introduced a mechanism to execute a global clock
update for a vm. We can apply this periodically in order to propagate
host NTP corrections. Also, if all vcpus of a vm are pinned, then
without an additional trigger, no guest NTP corrections can propagate
either, as the current trigger is only vcpu cpu migration.
Signed-off-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When we update a vcpu's local clock it may pick up an NTP correction.
We can't wait an indeterminate amount of time for other vcpus to pick
up that correction, so commit 0061d53d introduced a global clock
update. However, we can't request a global clock update on every vcpu
load either (which is what happens if the tsc is marked as unstable).
The solution is to rate-limit the global clock updates. Marcelo
calculated that we should delay the global clock updates no more
than 0.1s as follows:

Assume an NTP correction c is applied to one vcpu, but not the other,
then in n seconds the delta of the vcpu system_timestamps will be
c * n. If we assume a correction of 500ppm (worst-case), then the two
vcpus will diverge 50us in 0.1s, which is a considerable amount.
Signed-off-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commit e504c909 (kvm, vmx: Fix lazy FPU on nested guest, 2013-11-13)
highlighted a real problem, but the fix was subtly wrong.

nested_read_cr0 is the CR0 as read by L2, but here we want to look at
the CR0 value reflecting L1's setup.  In other words, L2 might think
that TS=0 (so nested_read_cr0 has the bit clear); but if L1 is actually
running it with TS=1, we should inject the fault into L1.

The effective value of CR0 in L2 is contained in vmcs12->guest_cr0, use
it.

Fixes: e504c909Reported-by: NKashyap Chamarty <kchamart@redhat.com>
Reported-by: NStefan Bader <stefan.bader@canonical.com>
Tested-by: NKashyap Chamarty <kchamart@redhat.com>
Tested-by: NAnthoine Bourgeois <bourgeois@bertin.fr>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commit e504c909 (kvm, vmx: Fix lazy FPU on nested guest, 2013-11-13)
highlighted a real problem, but the fix was subtly wrong.

nested_read_cr0 is the CR0 as read by L2, but here we want to look at
the CR0 value reflecting L1's setup.  In other words, L2 might think
that TS=0 (so nested_read_cr0 has the bit clear); but if L1 is actually
running it with TS=1, we should inject the fault into L1.

The effective value of CR0 in L2 is contained in vmcs12->guest_cr0, use
it.

Fixes: e504c909Reported-by: NKashyap Chamarty <kchamart@redhat.com>
Reported-by: NStefan Bader <stefan.bader@canonical.com>
Tested-by: NKashyap Chamarty <kchamart@redhat.com>
Tested-by: NAnthoine Bourgeois <bourgeois@bertin.fr>
Cc: stable@vger.kernel.org
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The problem occurs when the guest performs a pusha with the stack
address pointing to an mmio address (or an invalid guest physical
address) to start with, but then extending into an ordinary guest
physical address.  When doing repeated emulated pushes
emulator_read_write sets mmio_needed to 1 on the first one.  On a
later push when the stack points to regular memory,
mmio_nr_fragments is set to 0, but mmio_is_needed is not set to 0.

As a result, KVM exits to userspace, and then returns to
complete_emulated_mmio.  In complete_emulated_mmio
vcpu->mmio_cur_fragment is incremented.  The termination condition of
vcpu->mmio_cur_fragment == vcpu->mmio_nr_fragments is never achieved.
The code bounces back and fourth to userspace incrementing
mmio_cur_fragment past it's buffer.  If the guest does nothing else it
eventually leads to a a crash on a memcpy from invalid memory address.

However if a guest code can cause the vm to be destroyed in another
vcpu with excellent timing, then kvm_clear_async_pf_completion_queue
can be used by the guest to control the data that's pointed to by the
call to cancel_work_item, which can be used to gain execution.

Fixes: f78146b0Signed-off-by: NAndrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org (3.5+)
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

No need to scan the entire VCPU array.
Signed-off-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Read-only large sptes can be created due to read-only faults as
follows:

- QEMU pagetable entry that maps guest memory is read-only
due to COW.
- Guest read faults such memory, COW is not broken, because
it is a read-only fault.
- Enable dirty logging, large spte not nuked because it is read-only.
- Write-fault on such memory causes guest to loop endlessly
(which must go down to level 1 because dirty logging is enabled).

Fix by dropping large spte when necessary.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

emulator_cmpxchg_emulated writes to guest memory, therefore it should
update the dirty bitmap accordingly.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Reviewed-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From 44c2abca2c2eadc6f2f752b66de4acc8131880c4 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Mon, 24 Feb 2014 18:12:31 +0800
Subject: [PATCH v5 3/3] KVM: x86: Enable Intel MPX for guest

This patch enable Intel MPX feature to guest.
Signed-off-by: NXudong Hao <xudong.hao@intel.com>
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From 5d5a80cd172ea6fb51786369bcc23356b1e9e956 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Mon, 24 Feb 2014 18:11:55 +0800
Subject: [PATCH v5 2/3] KVM: x86: add MSR_IA32_BNDCFGS to msrs_to_save

Add MSR_IA32_BNDCFGS to msrs_to_save, and corresponding logic
to kvm_get/set_msr().
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From caddc009a6d2019034af8f2346b2fd37a81608d0 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Mon, 24 Feb 2014 18:11:11 +0800
Subject: [PATCH v5 1/3] KVM: x86: Intel MPX vmx and msr handle

This patch handle vmx and msr of Intel MPX feature.
Signed-off-by: NXudong Hao <xudong.hao@intel.com>
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From 00c920c96127d20d4c3bb790082700ae375c39a0 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Fri, 21 Feb 2014 23:47:18 +0800
Subject: [PATCH] KVM: x86: Fix xsave cpuid exposing bug

EBX of cpuid(0xD, 0) is dynamic per XCR0 features enable/disable.
Bit 63 of XCR0 is reserved for future expansion.
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From 0750e335eb5860b0b483e217e8a08bd743cbba16 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Thu, 20 Feb 2014 17:39:32 +0800
Subject: [PATCH] KVM: x86: expose ADX feature to guest

ADCX and ADOX instructions perform an unsigned addition with Carry flag and
Overflow flag respectively.
Signed-off-by: NXudong Hao <xudong.hao@intel.com>
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

From 24ffdce9efebf13c6ed4882f714b2b57ef1141eb Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
Date: Thu, 20 Feb 2014 17:38:26 +0800
Subject: [PATCH] KVM: x86: expose new instruction RDSEED to guest

RDSEED instruction return a random number, which supplied by a
cryptographically secure, deterministic random bit generator(DRBG).
Signed-off-by: NXudong Hao <xudong.hao@intel.com>
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We should open NMI window right after an iret, but SVM exits before it.
We wanted to single step using the trap flag and then open it.
(or we could emulate the iret instead)
We don't do it since commit 3842d135 (likely), because the iret exit
handler does not request an event, so NMI window remains closed until
the next exit.

Fix this by making KVM_REQ_EVENT request in the iret handler.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When this was introduced, kvm_flush_remote_tlbs() could be called
without holding mmu_lock.  It is now acknowledged that the function
must be called before releasing mmu_lock, and all callers have already
been changed to do so.

There is no need to use smp_mb() and cmpxchg() any more.
Signed-off-by: NTakuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Remove unused last_kernel_ns variable.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

By setting a Kconfig option, the architecture can control when
guest notifications will be presented by the apf backend.
There is the default batch mechanism, working as before, where the vcpu
thread should pull in this information.
Opposite to this, there is now the direct mechanism, that will push the
information to the guest.
This way s390 can use an already existing architecture interface.

Still the vcpu thread should call check_completion to cleanup leftovers.
Signed-off-by: NDominik Dingel <dingel@linux.vnet.ibm.com>
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>

Self explanatory.
Reported-by: NRadim Krcmar <rkrcmar@redhat.com>
Cc: Vadim Rozenfeld <vrozenfe@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Check for invalid state transitions on guest-initiated updates of
MSR_IA32_APICBASE. This address both enabling of the x2APIC when it is
not supported and all invalid transitions as described in SDM section
10.12.5. It also checks that no reserved bit is set in APICBASE by the
guest.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
[Use cpuid_maxphyaddr instead of guest_cpuid_get_phys_bits. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NVadim Rozenfeld <vrozenfe@redhat.com>
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off-by: NVadim Rozenfeld <vrozenfe@redhat.com>
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Make KVM_MMU_AUDIT kconfig help text readable and collapse
two spaces between words down to one space.
Signed-off-by: NRandy Dunlap <rdunlap@infradead.org>
Reviewed-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Set guest activity state in L1's VMCS according to the VCPUs mp_state.
This ensures we report the correct state in case we L2 executed HLT or
if we put L2 into HLT state and it was now woken up by an event.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When we suspend the guest in HLT state, the nested run is no longer
pending - we emulated it completely. So only set nested_run_pending
after checking the activity state.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

This simplifies the code and also stops issuing warning about writing to
unhandled MSRs when VMX is disabled or the Feature Control MSR is
locked - we do handle them all according to the spec.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Already used by nested SVM for tracing nested vmexit: kvm_nested_vmexit
marks exits from L2 to L0 while kvm_nested_vmexit_inject marks vmexits
that are reflected to L1.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Instead of fixing up the vmcs12 after the nested vmexit, pass key
parameters already when calling nested_vmx_vmexit. This will help
tracing those vmexits.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When userspace sets MSR_IA32_FEATURE_CONTROL to 0, make sure we leave
root and non-root mode, fully disabling VMX. The register state of the
VCPU is undefined after this step, so userspace has to set it to a
proper state afterward.

This enables to reboot a VM while it is running some hypervisor code.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

According to the SDM, only bits 0-3 of DR6 "may" be cleared by "certain"
debug exception. So do update them on #DB exception in KVM, but leave
the rest alone, only setting BD and BS in addition to already set bits
in DR6. This also aligns us with kvm_vcpu_check_singlestep.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In contrast to VMX, SVM dose not automatically transfer DR6 into the
VCPU's arch.dr6. So if we face a DR6 read, we must consult a new vendor
hook to obtain the current value. And as SVM now picks the DR6 state
from its VMCB, we also need a set callback in order to write updates of
DR6 back.

Fixes a regression of 020df079.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Whenever we change arch.dr7, we also have to call kvm_update_dr7. In
case guest debugging is off, this will synchronize the new state into
hardware.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Signed-off: Peter Lieven <pl@kamp.de>
Signed-off: Gleb Natapov
Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>

After some consideration I decided to submit only Hyper-V reference
counters support this time. I will submit iTSC support as a separate
patch as soon as it is ready.

v1 -> v2
1. mark TSC page dirty as suggested by
    Eric Northup <digitaleric@google.com> and Gleb
2. disable local irq when calling get_kernel_ns,
    as it was done by Peter Lieven <pl@amp.de>
3. move check for TSC page enable from second patch
    to this one.

v3 -> v4
    Get rid of ref counter offset.

v4 -> v5
    replace __copy_to_user with kvm_write_guest
    when updateing iTSC page.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

After the previous patch from Marcelo, the comment before this write
became obsolete.  In fact, the write is unnecessary.  The calls to
kvm_write_tsc ultimately result in a master clock update as soon as
all TSCs agree and the master clock is re-enabled.  This master
clock update will rewrite tsc_timestamp.

So, together with the comment, delete the dead write too.
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

To fix a problem related to different resolution of TSC and system clock,
the offset in TSC units is approximated by

delta = vcpu->hv_clock.tsc_timestamp 	- 	vcpu->last_guest_tsc

(Guest TSC value at 			(Guest TSC value at last VM-exit)
the last kvm_guest_time_update
call)

Delta is then later scaled using mult,shift pair found in hv_clock
structure (which is correct against tsc_timestamp in that
structure).

However, if a frequency change is performed between these two points,
this delta is measured using different TSC frequencies, but scaled using
mult,shift pair for one frequency only.

The end result is an incorrect delta.

The bug which this code works around is not the only cause for
clock backwards events. The global accumulator is still
necessary, so remove the max_kernel_ns fix and rely on the
global accumulator for no clock backwards events.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commit e66d2ae7 moved the assignment
vcpu->arch.apic_base = value above a condition with
(vcpu->arch.apic_base ^ value), causing that check
to always fail. Use old_value, vcpu->arch.apic_base's
old value, in the condition instead.
Signed-off-by: NAndrew Jones <drjones@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Limit PIT timer frequency similarly to the limit applied by
LAPIC timer.

Cc: stable@kernel.org
Reviewed-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>