kvm updates the version number for the guest paravirt clock structure by
incrementing the version of its private copy. It does not read the guest
version, so will write version = 2 in the first update for every new VM,
including after restoring a saved state. If guest state is saved during
reading the clock, it could read and accept struct fields and guest TSC
from two different updates. This changes the code to increment the guest
version and write it back.
Signed-off-by: NOwen Hofmann <osh@google.com>
Reviewed-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commit 3b32004a ("KVM: x86: movnti minimum op size of 32-bit is not kept")
did not fully fix the minimum operand size of MONTI emulation. Still, MOVNTI
may be mistakenly performed using 16-bit opsize.

This patch add No16 flag to mark an instruction does not support 16-bits
operand size.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When the guest writes to the TSC, the masterclock TSC copy must be
updated as well along with the TSC_OFFSET update, otherwise a negative
tsc_timestamp is calculated at kvm_guest_time_update.

Once "if (!vcpus_matched && ka->use_master_clock)" is simplified to
"if (ka->use_master_clock)", the corresponding "if (!ka->use_master_clock)"
becomes redundant, so remove the do_request boolean and collapse
everything into a single condition.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Now that KVM injects #UD on "unhandlable" error, it makes better sense to
return such error on sysenter instead of directly injecting #UD to the guest.
This allows to track more easily the unhandlable cases the emulator does not
support.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

APIC base relocation is unsupported by KVM. If anyone uses it, the least should
be to report a warning in the hypervisor.

Note that KVM-unit-tests uses this feature for some reason, so running the
tests triggers the warning.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Commit 7fe864dc (KVM: x86: Mark VEX-prefix instructions emulation as
unimplemented, 2014-06-02) marked VEX instructions as such in protected
mode.  VEX-prefix instructions are not supported relevant on real-mode
and VM86, but should cause #UD instead of being decoded as LES/LDS.

Fix this behaviour to be consistent with real hardware.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
[Check for mod == 3, rather than 2 or 3. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Task-switch emulation checks the privilege level prior to performing the
task-switch.  This check is incorrect in the case of task-gates, in which the
tss.dpl is ignored, and can cause superfluous exceptions.  Moreover this check
is unnecassary, since the CPU checks the privilege levels prior to exiting.
Intel SDM 25.4.2 says "If CALL or JMP accesses a TSS descriptor directly
outside IA-32e mode, privilege levels are checked on the TSS descriptor" prior
to exiting.  AMD 15.14.1 says "The intercept is checked before the task switch
takes place but after the incoming TSS and task gate (if one was involved) have
been checked for correctness."

This patch removes the CPL checks for CALL and JMP.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When emulating LTR/LDTR/LGDT/LIDT, #GP should be injected if the base is
non-canonical. Otherwise, VM-entry will fail.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

LGDT and LIDT emulation logic is almost identical. Merge the logic into a
single point to avoid redundancy. This will be used by the next patch that
will ensure the bases of the loaded GDTR and IDTR are canonical.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the emulation ends in fault, eflags should not be updated.  However, several
instruction emulations (actually all the fastops) currently update eflags, if
the fault was detected afterwards (e.g., #PF during writeback).
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Although Intel SDM mentions bit 63 is reserved, MOV to CR3 can have bit 63 set.
As Intel SDM states in section 4.10.4 "Invalidation of TLBs and
Paging-Structure Caches": " MOV to CR3. ... If CR4.PCIDE = 1 and bit 63 of the
instruction’s source operand is 0 ..."

In other words, bit 63 is not reserved. KVM emulator currently consider bit 63
as reserved. Fix it.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

According to Intel SDM push of segment selectors is done in the following
manner: "if the operand size is 32-bits, either a zero-extended value is pushed
on the stack or the segment selector is written on the stack using a 16-bit
move. For the last case, all recent Core and Atom processors perform a 16-bit
move, leaving the upper portion of the stack location unmodified."

This patch modifies the behavior to match the core behavior.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

CMPS and SCAS instructions are evaluated in the wrong order.  For reference (of
CMPS), see http://www.fermimn.gov.it/linux/quarta/x86/cmps.htm : "Note that the
direction of subtraction for CMPS is [SI] - [DI] or [ESI] - [EDI]. The left
operand (SI or ESI) is the source and the right operand (DI or EDI) is the
destination. This is the reverse of the usual Intel convention in which the
left operand is the destination and the right operand is the source."

Introducing em_cmp_r for this matter that performs comparison in reverse order
using fastop infrastructure to avoid a wrapper function.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

SYSCALL emulation currently clears in 64-bit mode eflags according to
MSR_SYSCALL_MASK.  However, on bare-metal eflags[1] which is fixed to one
cannot be cleared, even if MSR_SYSCALL_MASK masks the bit.  This wrong behavior
may result in failed VM-entry, as VT disallows entry with eflags[1] cleared.

This patch sets the bit after masking eflags on syscall.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In x86, you can only MOV-sreg to memory with either 16-bits or 64-bits size.
In contrast, KVM may write to 32-bits memory on MOV-sreg. This patch fixes KVM
behavior, and sets the destination operand size to two, if the destination is
memory.

When destination is registers, and the operand size is 32-bits, the high
16-bits in modern CPUs is filled with zero.  This is handled correctly.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

x86 debug registers hold a linear address. Therefore, breakpoints detection
should consider CS.base, and check whether instruction linear address equals
(CS.base + RIP). This patch introduces a function to evaluate RIP linear
address and uses it for breakpoints detection.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

DR6[0:3] (previous breakpoint indications) are cleared when #DB is injected
during handle_exception, just as real hardware does.  Similarily, handle_dr
should clear DR6[0:3].
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

It should clear B0-B3 and set BD.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Real-mode exceptions do not deliver error code. As can be seen in Intel SDM
volume 2, real-mode exceptions do not have parentheses, which indicate
error-code.  To avoid significant changes of the code, the error code is
"removed" during exception queueing.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In one occassion, decode_modrm uses the rm field after it is extended with
REX.B to determine the addressing mode. Doing so causes it not to read the
offset for rip-relative addressing with REX.B=1.

This patch moves the fetch where we already mask REX.B away instead.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

A bug was reported as follows: when running Windows 7 32-bit guests on qemu-kvm,
sometimes the guests run into blue screen during reboot. The problem was that a
guest's RVI was not cleared when it rebooted. This patch has fixed the problem.
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NYang Zhang <yang.z.zhang@intel.com>
Tested-by: NRongrong Liu &lt;rongrongx.liu@intel.com&gt;, Da Chun <ngugc@qq.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Return a negative error code instead, and WARN() when we should be covering
the entire 2-bit space of vmcs_field_type's return value.  For increased
robustness, add a BUILD_BUG_ON checking the range of vmcs_field_to_offset.
Suggested-by: NTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Instead of vmx_init(), actually it would make reasonable sense to do
anything specific to vmx hardware setting in vmx_x86_ops->hardware_setup().
Signed-off-by: NTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Just move this pair of functions down to make sure later we can
add something dependent on others.
Signed-off-by: NTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We can use get_cpu() and put_cpu() to replace
preempt_disable()/cpu = smp_processor_id() and
preempt_enable() for slightly better code.
Signed-off-by: NTiejun Chen <tiejun.chen@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

We mirror a subset of these registers in separate variables.
Using them directly should be faster.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

APIC-write VM exits are "trap-like": they save CS:RIP values for the
instruction after the write, and more importantly, the handler will
already see the new value in the virtual-APIC page.  This means that
apic_reg_write cannot use kvm_apic_get_reg to omit timer cancelation
when mode changes.

timer_mode_mask shouldn't be changing as it depends on cpuid.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

APIC-write VM exits are "trap-like": they save CS:RIP values for the
instruction after the write, and more importantly, the handler will
already see the new value in the virtual-APIC page.

This caused a bug if you used KVM_SET_IRQCHIP to set the SW-enabled bit
in the SPIV register.  The chain of events is as follows:

* When the irqchip is added to the destination VM, the apic_sw_disabled
static key is incremented (1)

* When the KVM_SET_IRQCHIP ioctl is invoked, it is decremented (0)

* When the guest disables the bit in the SPIV register, e.g. as part of
shutdown, apic_set_spiv does not notice the change and the static key is
_not_ incremented.

* When the guest is destroyed, the static key is decremented (-1),
resulting in this trace:

  WARNING: at kernel/jump_label.c:81 __static_key_slow_dec+0xa6/0xb0()
  jump label: negative count!

  [<ffffffff816bf898>] dump_stack+0x19/0x1b
  [<ffffffff8107c6f1>] warn_slowpath_common+0x61/0x80
  [<ffffffff8107c76c>] warn_slowpath_fmt+0x5c/0x80
  [<ffffffff811931e6>] __static_key_slow_dec+0xa6/0xb0
  [<ffffffff81193226>] static_key_slow_dec_deferred+0x16/0x20
  [<ffffffffa0637698>] kvm_free_lapic+0x88/0xa0 [kvm]
  [<ffffffffa061c63e>] kvm_arch_vcpu_uninit+0x2e/0xe0 [kvm]
  [<ffffffffa05ff301>] kvm_vcpu_uninit+0x21/0x40 [kvm]
  [<ffffffffa067cec7>] vmx_free_vcpu+0x47/0x70 [kvm_intel]
  [<ffffffffa061bc50>] kvm_arch_vcpu_free+0x50/0x60 [kvm]
  [<ffffffffa061ca22>] kvm_arch_destroy_vm+0x102/0x260 [kvm]
  [<ffffffff810b68fd>] ? synchronize_srcu+0x1d/0x20
  [<ffffffffa06030d1>] kvm_put_kvm+0xe1/0x1c0 [kvm]
  [<ffffffffa06036f8>] kvm_vcpu_release+0x18/0x20 [kvm]
  [<ffffffff81215c62>] __fput+0x102/0x310
  [<ffffffff81215f4e>] ____fput+0xe/0x10
  [<ffffffff810ab664>] task_work_run+0xb4/0xe0
  [<ffffffff81083944>] do_exit+0x304/0xc60
  [<ffffffff816c8dfc>] ? _raw_spin_unlock_irq+0x2c/0x50
  [<ffffffff810fd22d>] ?  trace_hardirqs_on_caller+0xfd/0x1c0
  [<ffffffff8108432c>] do_group_exit+0x4c/0xc0
  [<ffffffff810843b4>] SyS_exit_group+0x14/0x20
  [<ffffffff816d33a9>] system_call_fastpath+0x16/0x1b
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Expose Intel AVX-512 feature bits to guest. Also add checks for
xcr0 AVX512 related bits according to spec:
http://download-software.intel.com/sites/default/files/managed/71/2e/319433-017.pdfSigned-off-by: NChao Peng <chao.p.peng@linux.intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

The check in kvm_set_lapic_tscdeadline_msr() was trying to prevent a
situation where we lose a pending deadline timer in a MSR write.
Losing it is fine, because it effectively occurs before the timer fired,
so we should be able to cancel or postpone it.

Another problem comes from interaction with QEMU, or other userspace
that can set deadline MSR without a good reason, when timer is already
pending:  one guest's deadline request results in more than one
interrupt because one is injected immediately on MSR write from
userspace and one through hrtimer later.

The solution is to remove the injection when replacing a pending timer
and to improve the usual QEMU path, we inject without a hrtimer when the
deadline has already passed.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Reported-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Make the code reusable.

If the timer was already pending, we shouldn't be waiting in a queue,
so wake_up can be skipped, simplifying the path.

There is no 'reinject' case => the comment is removed.
Current race behaves correctly.
Signed-off-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If DR4/5 is accessed when it is unavailable (since CR4.DE is set), then #UD
should be generated even if CPL>0. This is according to Intel SDM Table 6-2:
"Priority Among Simultaneous Exceptions and Interrupts".

Note, that this may happen on the first DR access, even if the host does not
sets debug breakpoints. Obviously, it occurs when the host debugs the guest.

This patch moves the DR4/5 checks from __kvm_set_dr/_kvm_get_dr to handle_dr.
The emulator already checks DR4/5 availability in check_dr_read. Nested
virutalization related calls to kvm_set_dr/kvm_get_dr would not like to inject
exceptions to the guest.

As for SVM, the patch follows the previous logic as much as possible. Anyhow,
it appears the DR interception code might be buggy - even if the DR access
may cause an exception, the instruction is skipped.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

When read access is performed using a readable code segment, the "conforming"
and "non-conforming" checks should not be done.  As a result, read using
non-conforming readable code segment fails.

This is according to Intel SDM 5.6.1 ("Accessing Data in Code Segments").

The fix is not to perform the "non-conforming" checks if the access is not a
fetch; the relevant checks are already done when loading the segment.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

DR7.LE should be cleared during task-switch. This feature is poorly documented.
For reference, see:
http://pdos.csail.mit.edu/6.828/2005/readings/i386/s12_02.htm

SDM [17.2.4]:
  This feature is not supported in the P6 family processors, later IA-32
  processors, and Intel 64 processors.

AMD [2:13.1.1.4]:
  This bit is ignored by implementations of the AMD64 architecture.

Intel's formulation could mean that it isn't even zeroed, but current
hardware indeed does not behave like that.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In long-mode, when the address size is 4 bytes, the linear address is not
truncated as the emulator mistakenly does.  Instead, the offset within the
segment (the ea field) should be truncated according to the address size.

As Intel SDM says: "In 64-bit mode, the effective address components are added
and the effective address is truncated ... before adding the full 64-bit
segment base."
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Intel SDM 17.2.4 (Debug Control Register (DR7)) says: "The processor clears the
GD flag upon entering to the debug exception handler." This sentence may be
misunderstood as if it happens only on #DB due to debug-register protection,
but it happens regardless to the cause of the #DB.

Fix the behavior to match both real hardware and Bochs.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

KVM does not deliver x2APIC broadcast messages with physical mode.  Intel SDM
(10.12.9 ICR Operation in x2APIC Mode) states: "A destination ID value of
FFFF_FFFFH is used for broadcast of interrupts in both logical destination and
physical destination modes."

In addition, the local-apic enables cluster mode broadcast. As Intel SDM
10.6.2.2 says: "Broadcast to all local APICs is achieved by setting all
destination bits to one." This patch enables cluster mode broadcast.

The fix tries to combine broadcast in different modes through a unified code.

One rare case occurs when the source of IPI has its APIC disabled.  In such
case, the source can still issue IPIs, but since the source is not obliged to
have the same LAPIC mode as the enabled ones, we cannot rely on it.
Since it is a rare case, it is unoptimized and done on the slow-path.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Reviewed-by: NRadim Krčmář <rkrcmar@redhat.com>
Reviewed-by: NWanpeng Li <wanpeng.li@linux.intel.com>
[As per Radim's review, use unsigned int for X2APIC_BROADCAST, return bool from
 kvm_apic_broadcast. - Paolo]
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

CR4.TSD is guest-owned; don't trap writes to it in VMX guests.  This
avoids a VM exit on context switches into or out of a PR_TSC_SIGSEGV
task.

I think that this fixes an unintentional side-effect of:
    4c38609a KVM: VMX: Make guest cr4 mask more conservative
Signed-off-by: NAndy Lutomirski <luto@amacapital.net>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

If the operand size is not 64-bit, then the sysexit instruction should assign
ECX to RSP and EDX to RIP.  The current code assigns the full 64-bits.

Fix it by masking.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In 64-bit, stack operations default to 64-bits, but can be overriden (to
16-bit) using opsize override prefix. In contrast, near-branches are always
64-bit.  This patch distinguish between the different behaviors.
Signed-off-by: NNadav Amit <namit@cs.technion.ac.il>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>