Using sp->role.level instead of @level since @level is not got from the
page table hierarchy
There is no issue in current code since the fast page fault currently only
fixes the fault caused by dirty-log that is always on the last level
(level = 1)
This patch makes the code more readable and avoids potential issue in the
further development
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This reverts commit 5befdc385d.
Since we will allow flush tlb out of mmu-lock in the later
patch
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
If EFER.LMA is off, cs.l does not determine execution mode.
Currently, the emulation engine assumes differently.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
The IN instruction is not be affected by REP-prefix as INS is. Therefore, the
emulation should ignore the REP prefix as well. The current emulator
implementation tries to perform writeback when IN instruction with REP-prefix
is emulated. This causes it to perform wrong memory write or spurious #GP
exception to be injected to the guest.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
According to Intel specifications, PAE and non-PAE does not have any reserved
bits. In long-mode, regardless to PCIDE, only the high bits (above the
physical address) are reserved.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
If a guest enables a performance counter but does not enable PMI, the
hypervisor currently does not reprogram the performance counter once it
overflows. As a result the host performance counter is kept with the original
sampling period which was configured according to the value of the guest's
counter when the counter was enabled.
Such behaviour can cause very bad consequences. The most distrubing one can
cause the guest not to make any progress at all, and keep exiting due to host
PMI before any guest instructions is exeucted. This situation occurs when the
performance counter holds a very high value when the guest enables the
performance counter. As a result the host's sampling period is configured to be
very short. The host then never reconfigures the sampling period and get stuck
at entry->PMI->exit loop. We encountered such a scenario in our experiments.
The solution is to reprogram the counter even if the guest does not use PMI.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Some Type 1 hypervisors such as XEN won't enable VMX without it present
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This feature emulates the "Acknowledge interrupt on exit" behavior.
We can safely emulate it for L1 to run L2 even if L0 itself has it
disabled (to run L1).
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
For single context invalidation, we fall through to global
invalidation in handle_invept() except for one case - when
the operand supplied by L1 is different from what we have in
vmcs12. However, typically hypervisors will only call invept
for the currently loaded eptp, so the condition will
never be true.
Signed-off-by: Bandan Das <bsd@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
When entering an exception after an ICEBP, the saved instruction
pointer should point to after the instruction.
This fixes the bug here: https://bugs.launchpad.net/qemu/+bug/1119686
Signed-off-by: Huw Davies <huw@codeweavers.com>
Reviewed-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
According to Intel specifications, only general purpose registers and segment
selectors should be saved in the old TSS during 32-bit task-switch.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
With KVM, MMIO is much slower than PIO, due to the need to
do page walk and emulation. But with EPT, it does not have to be: we
know the address from the VMCS so if the address is unique, we can look
up the eventfd directly, bypassing emulation.
Unfortunately, this only works if userspace does not need to match on
access length and data. The implementation adds a separate FAST_MMIO
bus internally. This serves two purposes:
- minimize overhead for old userspace that does not use eventfd with lengtth = 0
- minimize disruption in other code (since we don't know the length,
devices on the MMIO bus only get a valid address in write, this
way we don't need to touch all devices to teach them to handle
an invalid length)
At the moment, this optimization only has effect for EPT on x86.
It will be possible to speed up MMIO for NPT and MMU using the same
idea in the future.
With this patch applied, on VMX MMIO EVENTFD is essentially as fast as PIO.
I was unable to detect any measureable slowdown to non-eventfd MMIO.
Making MMIO faster is important for the upcoming virtio 1.0 which
includes an MMIO signalling capability.
The idea was suggested by Peter Anvin. Lots of thanks to Gleb for
pre-review and suggestions.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
It is sometimes benefitial to ignore IO size, and only match on address.
In hindsight this would have been a better default than matching length
when KVM_IOEVENTFD_FLAG_DATAMATCH is not set, In particular, this kind
of access can be optimized on VMX: there no need to do page lookups.
This can currently be done with many ioeventfds but in a suboptimal way.
However we can't change kernel/userspace ABI without risk of breaking
some applications.
Use len = 0 to mean "ignore length for matching" in a more optimal way.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
KVM does not handle the reserved bits of x86 page tables correctly:
In PAE, bits 5:8 are reserved in the PDPTE.
In IA-32e, bit 8 is not reserved.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Pull KVM fixes from Marcelo Tosatti:
- Fix for guest triggerable BUG_ON (CVE-2014-0155)
- CR4.SMAP support
- Spurious WARN_ON() fix
* git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: x86: remove WARN_ON from get_kernel_ns()
KVM: Rename variable smep to cr4_smep
KVM: expose SMAP feature to guest
KVM: Disable SMAP for guests in EPT realmode and EPT unpaging mode
KVM: Add SMAP support when setting CR4
KVM: Remove SMAP bit from CR4_RESERVED_BITS
KVM: ioapic: try to recover if pending_eoi goes out of range
KVM: ioapic: fix assignment of ioapic->rtc_status.pending_eoi (CVE-2014-0155)
Rename variable smep to cr4_smep, which can better reflect the
meaning of the variable.
Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
SMAP is disabled if CPU is in non-paging mode in hardware.
However KVM always uses paging mode to emulate guest non-paging
mode with TDP. To emulate this behavior, SMAP needs to be
manually disabled when guest switches to non-paging mode.
Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This patch adds SMAP handling logic when setting CR4 for guests
Thanks a lot to Paolo Bonzini for his suggestion to use the branchless
way to detect SMAP violation.
Signed-off-by: Feng Wu <feng.wu@intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
The purpose of this single series of commits from Srivatsa S Bhat (with
a small piece from Gautham R Shenoy) touching multiple subsystems that use
CPU hotplug notifiers is to provide a way to register them that will not
lead to deadlocks with CPU online/offline operations as described in the
changelog of commit 93ae4f978c (CPU hotplug: Provide lockless versions
of callback registration functions).
The first three commits in the series introduce the API and document it
and the rest simply goes through the users of CPU hotplug notifiers and
converts them to using the new method.
/
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Merge tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull CPU hotplug notifiers registration fixes from Rafael Wysocki:
"The purpose of this single series of commits from Srivatsa S Bhat
(with a small piece from Gautham R Shenoy) touching multiple
subsystems that use CPU hotplug notifiers is to provide a way to
register them that will not lead to deadlocks with CPU online/offline
operations as described in the changelog of commit 93ae4f978c ("CPU
hotplug: Provide lockless versions of callback registration
functions").
The first three commits in the series introduce the API and document
it and the rest simply goes through the users of CPU hotplug notifiers
and converts them to using the new method"
* tag 'cpu-hotplug-3.15-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (52 commits)
net/iucv/iucv.c: Fix CPU hotplug callback registration
net/core/flow.c: Fix CPU hotplug callback registration
mm, zswap: Fix CPU hotplug callback registration
mm, vmstat: Fix CPU hotplug callback registration
profile: Fix CPU hotplug callback registration
trace, ring-buffer: Fix CPU hotplug callback registration
xen, balloon: Fix CPU hotplug callback registration
hwmon, via-cputemp: Fix CPU hotplug callback registration
hwmon, coretemp: Fix CPU hotplug callback registration
thermal, x86-pkg-temp: Fix CPU hotplug callback registration
octeon, watchdog: Fix CPU hotplug callback registration
oprofile, nmi-timer: Fix CPU hotplug callback registration
intel-idle: Fix CPU hotplug callback registration
clocksource, dummy-timer: Fix CPU hotplug callback registration
drivers/base/topology.c: Fix CPU hotplug callback registration
acpi-cpufreq: Fix CPU hotplug callback registration
zsmalloc: Fix CPU hotplug callback registration
scsi, fcoe: Fix CPU hotplug callback registration
scsi, bnx2fc: Fix CPU hotplug callback registration
scsi, bnx2i: Fix CPU hotplug callback registration
...
Pull kvm updates from Paolo Bonzini:
"PPC and ARM do not have much going on this time. Most of the cool
stuff, instead, is in s390 and (after a few releases) x86.
ARM has some caching fixes and PPC has transactional memory support in
guests. MIPS has some fixes, with more probably coming in 3.16 as
QEMU will soon get support for MIPS KVM.
For x86 there are optimizations for debug registers, which trigger on
some Windows games, and other important fixes for Windows guests. We
now expose to the guest Broadwell instruction set extensions and also
Intel MPX. There's also a fix/workaround for OS X guests, nested
virtualization features (preemption timer), and a couple kvmclock
refinements.
For s390, the main news is asynchronous page faults, together with
improvements to IRQs (floating irqs and adapter irqs) that speed up
virtio devices"
* tag 'kvm-3.15-1' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (96 commits)
KVM: PPC: Book3S HV: Save/restore host PMU registers that are new in POWER8
KVM: PPC: Book3S HV: Fix decrementer timeouts with non-zero TB offset
KVM: PPC: Book3S HV: Don't use kvm_memslots() in real mode
KVM: PPC: Book3S HV: Return ENODEV error rather than EIO
KVM: PPC: Book3S: Trim top 4 bits of physical address in RTAS code
KVM: PPC: Book3S HV: Add get/set_one_reg for new TM state
KVM: PPC: Book3S HV: Add transactional memory support
KVM: Specify byte order for KVM_EXIT_MMIO
KVM: vmx: fix MPX detection
KVM: PPC: Book3S HV: Fix KVM hang with CONFIG_KVM_XICS=n
KVM: PPC: Book3S: Introduce hypervisor call H_GET_TCE
KVM: PPC: Book3S HV: Fix incorrect userspace exit on ioeventfd write
KVM: s390: clear local interrupts at cpu initial reset
KVM: s390: Fix possible memory leak in SIGP functions
KVM: s390: fix calculation of idle_mask array size
KVM: s390: randomize sca address
KVM: ioapic: reinject pending interrupts on KVM_SET_IRQCHIP
KVM: Bump KVM_MAX_IRQ_ROUTES for s390
KVM: s390: irq routing for adapter interrupts.
KVM: s390: adapter interrupt sources
...
Pull x86 cpufeature update from Ingo Molnar:
"Two refinements to clflushopt support"
* 'x86-cpufeature-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86, cpufeature: If we disable CLFLUSH, we should disable CLFLUSHOPT
x86, cpufeature: Rename X86_FEATURE_CLFLSH to X86_FEATURE_CLFLUSH
kvm_x86_ops is still NULL at this point. Since kvm_init_msr_list
cannot fail, it is safe to initialize it before the call.
Fixes: 93c4adc7af
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Tested-by: Jet Chen <jet.chen@intel.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Subsystems that want to register CPU hotplug callbacks, as well as perform
initialization for the CPUs that are already online, often do it as shown
below:
get_online_cpus();
for_each_online_cpu(cpu)
init_cpu(cpu);
register_cpu_notifier(&foobar_cpu_notifier);
put_online_cpus();
This is wrong, since it is prone to ABBA deadlocks involving the
cpu_add_remove_lock and the cpu_hotplug.lock (when running concurrently
with CPU hotplug operations).
Instead, the correct and race-free way of performing the callback
registration is:
cpu_notifier_register_begin();
for_each_online_cpu(cpu)
init_cpu(cpu);
/* Note the use of the double underscored version of the API */
__register_cpu_notifier(&foobar_cpu_notifier);
cpu_notifier_register_done();
Fix the kvm code in x86 by using this latter form of callback registration.
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
When doing nested virtualization, we may be able to read BNDCFGS but
still not be allowed to write to GUEST_BNDCFGS in the VMCS. Guard
writes to the field with vmx_mpx_supported(), and similarly hide the
MSR from userspace if the processor does not support the field.
We could work around this with the generic MSR save/load machinery,
but there is only a limited number of MSR save/load slots and it is
not really worthwhile to waste one for a scenario that should not
happen except in the nested virtualization case.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This is simple to do, the "host" BNDCFGS is either 0 or the guest value.
However, both controls have to be present. We cannot provide MPX if
we only have one of the "load BNDCFGS" or "clear BNDCFGS" controls.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
XSAVE support for KVM is already using host_xcr0 & KVM_SUPPORTED_XCR0 as
a "dynamic" version of KVM_SUPPORTED_XCR0.
However, this is not enough because the MPX bits should not be presented
to the guest unless kvm_x86_ops confirms the support. So, replace all
instances of host_xcr0 & KVM_SUPPORTED_XCR0 with a new function
kvm_supported_xcr0() that also has this check.
Note that here:
if (xstate_bv & ~KVM_SUPPORTED_XCR0)
return -EINVAL;
if (xstate_bv & ~host_cr0)
return -EINVAL;
the code is equivalent to
if ((xstate_bv & ~KVM_SUPPORTED_XCR0) ||
(xstate_bv & ~host_cr0)
return -EINVAL;
i.e. "xstate_bv & (~KVM_SUPPORTED_XCR0 | ~host_cr0)" which is in turn
equal to "xstate_bv & ~(KVM_SUPPORTED_XCR0 & host_cr0)". So we should
also use the new function there.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add emulation for 0x66 prefixed instruction of 0f 28 opcode
that has been added earlier.
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Paolo 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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Gabriel L. Somlo <somlo@cmu.edu>
[Move documentation to KVM_IRQ_LINE, add ia64. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
We always disable cr8 intercept in its handler, but only re-enable it
if handling KVM_REQ_EVENT, so there can be a window where we do not
intercept cr8 writes, which allows an interrupt to disrupt a higher
priority task.
Fix this by disabling intercepts in the same function that re-enables
them when needed. This fixes BSOD in Windows 2008.
Cc: <stable@vger.kernel.org>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When not running in guest-debug mode (i.e. the guest controls the debug
registers, having to take an exit for each DR access is a waste of time.
If the guest gets into a state where each context switch causes DR to be
saved and restored, this can take away as much as 40% of the execution
time from the guest.
If the guest is running with vcpu->arch.db == vcpu->arch.eff_db, we
can let it write freely to the debug registers and reload them on the
next exit. We still need to exit on the first access, so that the
KVM_DEBUGREG_WONT_EXIT flag is set in switch_db_regs; after that, further
accesses to the debug registers will not cause a vmexit.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Unlike other intercepts, debug register intercepts will be modified
in hot paths if the guest OS is bad or otherwise gets tricked into
doing so.
Avoid calling recalc_intercepts 16 times for debug registers.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When preparing the VMCS02, the CPU-based execution controls is computed
by vmx_exec_control. Turn off DR access exits there, too, if the
KVM_DEBUGREG_WONT_EXIT bit is set in switch_db_regs.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When not running in guest-debug mode (i.e. the guest controls the debug
registers, having to take an exit for each DR access is a waste of time.
If the guest gets into a state where each context switch causes DR to be
saved and restored, this can take away as much as 40% of the execution
time from the guest.
If the guest is running with vcpu->arch.db == vcpu->arch.eff_db, we
can let it write freely to the debug registers and reload them on the
next exit. We still need to exit on the first access, so that the
KVM_DEBUGREG_WONT_EXIT flag is set in switch_db_regs; after that, further
accesses to the debug registers will not cause a vmexit.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When not running in guest-debug mode, the guest controls the debug
registers and having to take an exit for each DR access is a waste
of time. If the guest gets into a state where each context switch
causes DR to be saved and restored, this can take away as much as 40%
of the execution time from the guest.
After this patch, VMX- and SVM-specific code can set a flag in
switch_db_regs, telling vcpu_enter_guest that on the next exit the debug
registers might be dirty and need to be reloaded (syncing will be taken
care of by a new callback in kvm_x86_ops). This flag can be set on the
first access to a debug registers, so that multiple accesses to the
debug registers only cause one vmexit.
Note that since the guest will be able to read debug registers and
enable breakpoints in DR7, we need to ensure that they are synchronized
on entry to the guest---including DR6 that was not synced before.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Currently, this works even if the bit is not in "min", because the bit is always
set in MSR_IA32_VMX_ENTRY_CTLS. Mention it for the sake of documentation, and
to avoid surprises if we later switch to MSR_IA32_VMX_TRUE_ENTRY_CTLS.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It's no longer possible to enter enable_irq_window in guest mode when
L1 intercepts external interrupts and we are entering L2. This is now
caught in vcpu_enter_guest. So we can remove the check from the VMX
version of enable_irq_window, thus the need to return an error code from
both enable_irq_window and enable_nmi_window.
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo 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: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo 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: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
commit 0061d53daf 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: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo 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 0061d53daf 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: Andrew Jones <drjones@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit e504c9098e (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: e504c9098e
Reported-by: Kashyap Chamarty <kchamart@redhat.com>
Reported-by: Stefan Bader <stefan.bader@canonical.com>
Tested-by: Kashyap Chamarty <kchamart@redhat.com>
Tested-by: Anthoine Bourgeois <bourgeois@bertin.fr>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Commit e504c9098e (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: e504c9098e
Reported-by: Kashyap Chamarty <kchamart@redhat.com>
Reported-by: Stefan Bader <stefan.bader@canonical.com>
Tested-by: Kashyap Chamarty <kchamart@redhat.com>
Tested-by: Anthoine Bourgeois <bourgeois@bertin.fr>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo 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: f78146b0f9
Signed-off-by: Andrew Honig <ahonig@google.com>
Cc: stable@vger.kernel.org (3.5+)
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
No need to scan the entire VCPU array.
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
