This new IOCTL exports all yet user-invisible states related to
exceptions, interrupts, and NMIs. Together with appropriate user space
changes, this fixes sporadic problems of vmsave/restore, live migration
and system reset.

[avi: future-proof abi by adding a flags field]
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Decouple KVM_GUESTDBG_INJECT_DB and KVM_GUESTDBG_INJECT_BP from
KVM_GUESTDBG_ENABLE, their are actually orthogonal. At this chance,
avoid triggering the WARN_ON in kvm_queue_exception if there is already
an exception pending and reject such invalid requests.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Otherwise kvm might attempt to dereference a NULL pointer.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Otherwise kvm will leak memory on multiple KVM_CREATE_IRQCHIP.
Also serialize multiple accesses with kvm->lock.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

GUEST_CR3 is updated via kvm_set_cr3 whenever CR3 is modified from
outside guest context. Similarly pdptrs are updated via load_pdptrs.

Let kvm_set_cr3 perform the update, removing it from the vcpu_run
fast path.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Acked-by: NAcked-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Probably introduced by a bad merge.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The various syscall-related MSRs are fairly expensive to switch.  Currently
we switch them on every vcpu preemption, which is far too often:

- if we're switching to a kernel thread (idle task, threaded interrupt,
  kernel-mode virtio server (vhost-net), for example) and back, then
  there's no need to switch those MSRs since kernel threasd won't
  be exiting to userspace.

- if we're switching to another guest running an identical OS, most likely
  those MSRs will have the same value, so there's little point in reloading
  them.

- if we're running the same OS on the guest and host, the MSRs will have
  identical values and reloading is unnecessary.

This patch uses the new user return notifiers to implement last-minute
switching, and checks the msr values to avoid unnecessary reloading.
Signed-off-by: NAvi Kivity <avi@redhat.com>

When we migrate a kvm guest that uses pvclock between two hosts, we may
suffer a large skew. This is because there can be significant differences
between the monotonic clock of the hosts involved. When a new host with
a much larger monotonic time starts running the guest, the view of time
will be significantly impacted.

Situation is much worse when we do the opposite, and migrate to a host with
a smaller monotonic clock.

This proposed ioctl will allow userspace to inform us what is the monotonic
clock value in the source host, so we can keep the time skew short, and
more importantly, never goes backwards. Userspace may also need to trigger
the current data, since from the first migration onwards, it won't be
reflected by a simple call to clock_gettime() anymore.

[marcelo: future-proof abi with a flags field]
[jan: fix KVM_GET_CLOCK by clearing flags field instead of checking it]
Signed-off-by: NGlauber Costa <glommer@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Commit 705c5323 opened the doors of hell by unconditionally injecting
single-step flags as long as guest_debug signaled this. This doesn't
work when the guest branches into some interrupt or exception handler
and triggers a vmexit with flag reloading.

Fix it by saving cs:rip when user space requests single-stepping and
restricting the trace flag injection to this guest code position.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Support for Xen PV-on-HVM guests can be implemented almost entirely in
userspace, except for handling one annoying MSR that maps a Xen
hypercall blob into guest address space.

A generic mechanism to delegate MSR writes to userspace seems overkill
and risks encouraging similar MSR abuse in the future.  Thus this patch
adds special support for the Xen HVM MSR.

I implemented a new ioctl, KVM_XEN_HVM_CONFIG, that lets userspace tell
KVM which MSR the guest will write to, as well as the starting address
and size of the hypercall blobs (one each for 32-bit and 64-bit) that
userspace has loaded from files.  When the guest writes to the MSR, KVM
copies one page of the blob from userspace to the guest.

I've tested this patch with a hacked-up version of Gerd's userspace
code, booting a number of guests (CentOS 5.3 i386 and x86_64, and
FreeBSD 8.0-RC1 amd64) and exercising PV network and block devices.

[jan: fix i386 build warning]
[avi: future proof abi with a flags field]
Signed-off-by: NEd Swierk <eswierk@aristanetworks.com>
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

This (broken) check dates back to the days when this code was shared
across architectures. x86 has IOMEM, so drop it.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

If cpufreq can't determine the CPU khz, or cpufreq is not compiled in,
we should fallback to the measured TSC khz.
Signed-off-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a tracepoint for the event that the guest
executed the SKINIT instruction. This information is
important because SKINIT is an SVM extenstion not yet
implemented by nested SVM and we may need this information
for debugging hypervisors that do not yet run on nested SVM.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a tracepoint for the event that the guest
executed the INVLPGA instruction.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a special tracepoint for the event that a
nested #vmexit is injected because kvm wants to inject an
interrupt into the guest.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a tracepoint for a nested #vmexit that gets
re-injected to the guest.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a tracepoint for every #vmexit we get from a
nested guest.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

This patch adds a dedicated kvm tracepoint for a nested
vmrun.
Signed-off-by: NJoerg Roedel <joerg.roedel@amd.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

For a while now, we are issuing a rdmsr instruction to find out which
msrs in our save list are really supported by the underlying machine.
However, it fails to account for kvm-specific msrs, such as the pvclock
ones.

This patch moves then to the beginning of the list, and skip testing them.

Cc: stable@kernel.org
Signed-off-by: NGlauber Costa <glommer@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Push TF and RF injection and filtering on guest single-stepping into the
vender get/set_rflags callbacks. This makes the whole mechanism more
robust wrt user space IOCTL order and instruction emulations.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Disable paravirt MMU capability reporting, so that new (or rebooted)
guests switch to native operation.

Paravirt MMU is a burden to maintain and does not bring significant
advantages compared to shadow anymore.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Much of so far vendor-specific code for setting up guest debug can
actually be handled by the generic code. This also fixes a minor deficit
in the SVM part /wrt processing KVM_GUESTDBG_ENABLE.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Now, also remove pre_task_link setting in save_state_to_tss16.

  commit b237ac37
  Author: Gleb Natapov <gleb@redhat.com>
  Date:   Mon Mar 30 16:03:24 2009 +0300

    KVM: Fix task switch back link handling.

CC: Gleb Natapov <gleb@redhat.com>
Signed-off-by: NJuan Quintela <quintela@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

They are globals, not clearly protected by any ordering or locking, and
vulnerable to various startup races.

Instead, for variable TSC machines, register the cpufreq notifier and get
the TSC frequency directly from the cpufreq machinery.  Not only is it
always right, it is also perfectly accurate, as no error prone measurement
is required.

On such machines, when a new CPU online is brought online, it isn't clear what
frequency it will start with, and it may not correspond to the reference, thus
in hardware_enable we clear the cpu_tsc_khz variable to zero and make sure
it is set before running on a VCPU.
Signed-off-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

Signed-off-by: NZachary Amsden <zamsden@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

X86 CPUs need to have some magic happening to enable the virtualization
extensions on them. This magic can result in unpleasant results for
users, like blocking other VMMs from working (vmx) or using invalid TLB
entries (svm).

Currently KVM activates virtualization when the respective kernel module
is loaded. This blocks us from autoloading KVM modules without breaking
other VMMs.

To circumvent this problem at least a bit, this patch introduces on
demand activation of virtualization. This means, that instead
virtualization is enabled on creation of the first virtual machine
and disabled on destruction of the last one.

So using this, KVM can be easily autoloaded, while keeping other
hypervisors usable.
Signed-off-by: NAlexander Graf <agraf@suse.de>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Not the incorrect -EINVAL.
Signed-off-by: NAvi Kivity <avi@redhat.com>

The only thing it protects now is interrupt injection into lapic and
this can work lockless. Even now with kvm->irq_lock in place access
to lapic is not entirely serialized since vcpu access doesn't take
kvm->irq_lock.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

The allows removal of irq_lock from the injection path.
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

They're just copies of vcpu->run, which is readily accessible.
Signed-off-by: NAvi Kivity <avi@redhat.com>

If TSS we are switching to resides in high memory task switch will fail
since address will be truncated. Windows2k3 does this sometimes when
running with more then 4G

Cc: stable@kernel.org
Signed-off-by: NGleb Natapov <gleb@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We only allocate memory for 32 MCE banks (KVM_MAX_MCE_BANKS) but we
allow user space to fill up to 255 on setup (mcg_cap & 0xff), corrupting
kernel memory. Catch these overflows.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

The number of entries is multiplied by the entry size, which can
overflow on 32-bit hosts.  Bound the entry count instead.
Reported-by: NDavid Wagner <daw@cs.berkeley.edu>
Cc: stable@kernel.org
Signed-off-by: NAvi Kivity <avi@redhat.com>

Debug registers may only be accessed from cpl 0.  Unfortunately, vmx will
code to emulate the instruction even though it was issued from guest
userspace, possibly leading to an unexpected trap later.

Cc: stable@kernel.org
Signed-off-by: NAvi Kivity <avi@redhat.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>

kvm_mmu_slot_remove_write_access already calls it.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

Instead of saving the debug registers from the processor to a kvm data
structure, rely in the debug registers stored in the thread structure.
This allows us not to save dr6 and dr7.

Reduces lightweight vmexit cost by 350 cycles, or 11 percent.
Signed-off-by: NAvi Kivity <avi@redhat.com>

update_cr8_intercept() can be triggered from userspace while there
is no apic present.
Signed-off-by: NAvi Kivity <avi@redhat.com>

Segment descriptors tables can be placed on two non-contiguous pages.
This patch makes reading segment descriptors by linear address.
Signed-off-by: NMikhail Ershov <Mike.Ershov@gmail.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

We're in arch/x86, what could we possibly be emulating?
Signed-off-by: NAvi Kivity <avi@redhat.com>

According to 16.2.5 in the SDM, eflags.vm in the tss is consulted before loading
and new segments.  If eflags.vm == 1, then the segments are treated as 16-bit
segments.  The LDTR and TR are not normally available in vm86 mode so if they
happen to somehow get loaded, they need to be treated as 32-bit segments.

This fixes an invalid vmentry failure in a custom OS that was happening after
a task switch into vm8086 mode.  Since the segments were being mistakenly
treated as 32-bit, we loaded garbage state.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>