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  1. 19 Sep, 2018 17 commits
    • Drew Schmitt's avatar
      KVM: x86: Control guest reads of MSR_PLATFORM_INFO · 6fbbde9a
      Drew Schmitt authored 
      Add KVM_CAP_MSR_PLATFORM_INFO so that userspace can disable guest access
to reads of MSR_PLATFORM_INFO.

Disabling access to reads of this MSR gives userspace the control to "expose"
this platform-dependent information to guests in a clear way. As it exists
today, guests that read this MSR would get unpopulated information if userspace
hadn't already set it (and prior to this patch series, only the CPUID faulting
information could have been populated). This existing interface could be
confusing if guests don't handle the potential for incorrect/incomplete
information gracefully (e.g. zero reported for base frequency).
Signed-off-by: default avatarDrew Schmitt <dasch@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      6fbbde9a
    • Drew Schmitt's avatar
      KVM: x86: Turbo bits in MSR_PLATFORM_INFO · d84f1cff
      Drew Schmitt authored 
      Allow userspace to set turbo bits in MSR_PLATFORM_INFO. Previously, only
the CPUID faulting bit was settable. But now any bit in
MSR_PLATFORM_INFO would be settable. This can be used, for example, to
convey frequency information about the platform on which the guest is
running.
Signed-off-by: default avatarDrew Schmitt <dasch@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d84f1cff
    • Krish Sadhukhan's avatar
      nVMX x86: Check VPID value on vmentry of L2 guests · ba8e23db
      Krish Sadhukhan authored 
      According to section "Checks on VMX Controls" in Intel SDM vol 3C, the
following check needs to be enforced on vmentry of L2 guests:

    If the 'enable VPID' VM-execution control is 1, the value of the
    of the VPID VM-execution control field must not be 0000H.
Signed-off-by: default avatarKrish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: default avatarMark Kanda <mark.kanda@oracle.com>
Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
Reviewed-by: default avatarJim Mattson <jmattson@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      ba8e23db
    • Krish Sadhukhan's avatar
      nVMX x86: check posted-interrupt descriptor addresss on vmentry of L2 · 6de84e58
      Krish Sadhukhan authored 
      According to section "Checks on VMX Controls" in Intel SDM vol 3C,
the following check needs to be enforced on vmentry of L2 guests:

   - Bits 5:0 of the posted-interrupt descriptor address are all 0.
   - The posted-interrupt descriptor address does not set any bits
     beyond the processor's physical-address width.
Signed-off-by: default avatarKrish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: default avatarMark Kanda <mark.kanda@oracle.com>
Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
Reviewed-by: default avatarDarren Kenny <darren.kenny@oracle.com>
Reviewed-by: default avatarKarl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      6de84e58
    • Liran Alon's avatar
      KVM: nVMX: Wake blocked vCPU in guest-mode if pending interrupt in virtual APICv · e6c67d8c
      Liran Alon authored 
      In case L1 do not intercept L2 HLT or enter L2 in HLT activity-state,
it is possible for a vCPU to be blocked while it is in guest-mode.

According to Intel SDM 26.6.5 Interrupt-Window Exiting and
Virtual-Interrupt Delivery: "These events wake the logical processor
if it just entered the HLT state because of a VM entry".
Therefore, if L1 enters L2 in HLT activity-state and L2 has a pending
deliverable interrupt in vmcs12->guest_intr_status.RVI, then the vCPU
should be waken from the HLT state and injected with the interrupt.

In addition, if while the vCPU is blocked (while it is in guest-mode),
it receives a nested posted-interrupt, then the vCPU should also be
waken and injected with the posted interrupt.

To handle these cases, this patch enhances kvm_vcpu_has_events() to also
check if there is a pending interrupt in L2 virtual APICv provided by
L1. That is, it evaluates if there is a pending virtual interrupt for L2
by checking RVI[7:4] > VPPR[7:4] as specified in Intel SDM 29.2.1
Evaluation of Pending Interrupts.

Note that this also handles the case of nested posted-interrupt by the
fact RVI is updated in vmx_complete_nested_posted_interrupt() which is
called from kvm_vcpu_check_block() -> kvm_arch_vcpu_runnable() ->
kvm_vcpu_running() -> vmx_check_nested_events() ->
vmx_complete_nested_posted_interrupt().
Reviewed-by: default avatarNikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: default avatarDarren Kenny <darren.kenny@oracle.com>
Signed-off-by: default avatarLiran Alon <liran.alon@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      e6c67d8c
    • Paolo Bonzini's avatar
      KVM: VMX: check nested state and CR4.VMXE against SMM · 5bea5123
      Paolo Bonzini authored 
      VMX cannot be enabled under SMM, check it when CR4 is set and when nested
virtualization state is restored.

This should fix some WARNs reported by syzkaller, mostly around
alloc_shadow_vmcs.
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      5bea5123
    • Sebastian Andrzej Siewior's avatar
      kvm: x86: make kvm_{load|put}_guest_fpu() static · 822f312d
      Sebastian Andrzej Siewior authored 
      The functions
	kvm_load_guest_fpu()
	kvm_put_guest_fpu()

are only used locally, make them static. This requires also that both
functions are moved because they are used before their implementation.
Those functions were exported (via EXPORT_SYMBOL) before commit
e5bb4025 ("KVM: Drop kvm_{load,put}_guest_fpu() exports").
Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      822f312d
    • Vitaly Kuznetsov's avatar
      x86/hyper-v: rename ipi_arg_{ex,non_ex} structures · a1efa9b7
      Vitaly Kuznetsov authored 
      These structures are going to be used from KVM code so let's make
their names reflect their Hyper-V origin.
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: default avatarRoman Kagan <rkagan@virtuozzo.com>
Acked-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      a1efa9b7
    • Sean Christopherson's avatar
      KVM: VMX: use preemption timer to force immediate VMExit · d264ee0c
      Sean Christopherson authored 
      A VMX preemption timer value of '0' is guaranteed to cause a VMExit
prior to the CPU executing any instructions in the guest.  Use the
preemption timer (if it's supported) to trigger immediate VMExit
in place of the current method of sending a self-IPI.  This ensures
that pending VMExit injection to L1 occurs prior to executing any
instructions in the guest (regardless of nesting level).

When deferring VMExit injection, KVM generates an immediate VMExit
from the (possibly nested) guest by sending itself an IPI.  Because
hardware interrupts are blocked prior to VMEnter and are unblocked
(in hardware) after VMEnter, this results in taking a VMExit(INTR)
before any guest instruction is executed.  But, as this approach
relies on the IPI being received before VMEnter executes, it only
works as intended when KVM is running as L0.  Because there are no
architectural guarantees regarding when IPIs are delivered, when
running nested the INTR may "arrive" long after L2 is running e.g.
L0 KVM doesn't force an immediate switch to L1 to deliver an INTR.

For the most part, this unintended delay is not an issue since the
events being injected to L1 also do not have architectural guarantees
regarding their timing.  The notable exception is the VMX preemption
timer[1], which is architecturally guaranteed to cause a VMExit prior
to executing any instructions in the guest if the timer value is '0'
at VMEnter.  Specifically, the delay in injecting the VMExit causes
the preemption timer KVM unit test to fail when run in a nested guest.

Note: this approach is viable even on CPUs with a broken preemption
timer, as broken in this context only means the timer counts at the
wrong rate.  There are no known errata affecting timer value of '0'.

[1] I/O SMIs also have guarantees on when they arrive, but I have
    no idea if/how those are emulated in KVM.
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
[Use a hook for SVM instead of leaving the default in x86.c - Paolo]
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d264ee0c
    • Sean Christopherson's avatar
      KVM: VMX: modify preemption timer bit only when arming timer · f459a707
      Sean Christopherson authored 
      Provide a singular location where the VMX preemption timer bit is
set/cleared so that future usages of the preemption timer can ensure
the VMCS bit is up-to-date without having to modify unrelated code
paths.  For example, the preemption timer can be used to force an
immediate VMExit.  Cache the status of the timer to avoid redundant
VMREAD and VMWRITE, e.g. if the timer stays armed across multiple
VMEnters/VMExits.
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      f459a707
    • Sean Christopherson's avatar
      KVM: VMX: immediately mark preemption timer expired only for zero value · 4c008127
      Sean Christopherson authored 
      A VMX preemption timer value of '0' at the time of VMEnter is
architecturally guaranteed to cause a VMExit prior to the CPU
executing any instructions in the guest.  This architectural
definition is in place to ensure that a previously expired timer
is correctly recognized by the CPU as it is possible for the timer
to reach zero and not trigger a VMexit due to a higher priority
VMExit being signalled instead, e.g. a pending #DB that morphs into
a VMExit.

Whether by design or coincidence, commit f4124500 ("KVM: nVMX:
Fully emulate preemption timer") special cased timer values of '0'
and '1' to ensure prompt delivery of the VMExit.  Unlike '0', a
timer value of '1' has no has no architectural guarantees regarding
when it is delivered.

Modify the timer emulation to trigger immediate VMExit if and only
if the timer value is '0', and document precisely why '0' is special.
Do this even if calibration of the virtual TSC failed, i.e. VMExit
will occur immediately regardless of the frequency of the timer.
Making only '0' a special case gives KVM leeway to be more aggressive
in ensuring the VMExit is injected prior to executing instructions in
the nested guest, and also eliminates any ambiguity as to why '1' is
a special case, e.g. why wasn't the threshold for a "short timeout"
set to 10, 100, 1000, etc...
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      4c008127
    • Andy Shevchenko's avatar
      KVM: SVM: Switch to bitmap_zalloc() · a101c9d6
      Andy Shevchenko authored 
      Switch to bitmap_zalloc() to show clearly what we are allocating.
Besides that it returns pointer of bitmap type instead of opaque void *.
Signed-off-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      a101c9d6
    • Tianyu Lan's avatar
      KVM/MMU: Fix comment in walk_shadow_page_lockless_end() · 9a984586
      Tianyu Lan authored 
      kvm_commit_zap_page() has been renamed to kvm_mmu_commit_zap_page()
This patch is to fix the commit.
Signed-off-by: default avatarLan Tianyu <Tianyu.Lan@microsoft.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      9a984586
    • Lei Yang's avatar
      kvm: selftests: use -pthread instead of -lpthread · 6bd317d3
      Lei Yang authored 
      I run into the following error

testing/selftests/kvm/dirty_log_test.c:285: undefined reference to `pthread_create'
testing/selftests/kvm/dirty_log_test.c:297: undefined reference to `pthread_join'
collect2: error: ld returned 1 exit status

my gcc version is gcc version 4.8.4
"-pthread" would work everywhere
Signed-off-by: default avatarLei Yang <Lei.Yang@windriver.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      6bd317d3
    • Wei Yang's avatar
      KVM: x86: don't reset root in kvm_mmu_setup() · 83b20b28
      Wei Yang authored 
      Here is the code path which shows kvm_mmu_setup() is invoked after
kvm_mmu_create(). Since kvm_mmu_setup() is only invoked in this code path,
this means the root_hpa and prev_roots are guaranteed to be invalid. And
it is not necessary to reset it again.

    kvm_vm_ioctl_create_vcpu()
        kvm_arch_vcpu_create()
            vmx_create_vcpu()
                kvm_vcpu_init()
                    kvm_arch_vcpu_init()
                        kvm_mmu_create()
        kvm_arch_vcpu_setup()
            kvm_mmu_setup()
                kvm_init_mmu()

This patch set reset_roots to false in kmv_mmu_setup().

Fixes: 50c28f21Signed-off-by: default avatarWei Yang <richard.weiyang@gmail.com>
Reviewed-by: default avatarLiran Alon <liran.alon@oracle.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      83b20b28
    • Junaid Shahid's avatar
      kvm: mmu: Don't read PDPTEs when paging is not enabled · d35b34a9
      Junaid Shahid authored 
      kvm should not attempt to read guest PDPTEs when CR0.PG = 0 and
CR4.PAE = 1.
Signed-off-by: default avatarJunaid Shahid <junaids@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d35b34a9
    • Vitaly Kuznetsov's avatar
      x86/kvm/lapic: always disable MMIO interface in x2APIC mode · d1766202
      Vitaly Kuznetsov authored 
      When VMX is used with flexpriority disabled (because of no support or
if disabled with module parameter) MMIO interface to lAPIC is still
available in x2APIC mode while it shouldn't be (kvm-unit-tests):

PASS: apic_disable: Local apic enabled in x2APIC mode
PASS: apic_disable: CPUID.1H:EDX.APIC[bit 9] is set
FAIL: apic_disable: *0xfee00030: 50014

The issue appears because we basically do nothing while switching to
x2APIC mode when APIC access page is not used. apic_mmio_{read,write}
only check if lAPIC is disabled before proceeding to actual write.

When APIC access is virtualized we correctly manipulate with VMX controls
in vmx_set_virtual_apic_mode() and we don't get vmexits from memory writes
in x2APIC mode so there's no issue.

Disabling MMIO interface seems to be easy. The question is: what do we
do with these reads and writes? If we add apic_x2apic_mode() check to
apic_mmio_in_range() and return -EOPNOTSUPP these reads and writes will
go to userspace. When lAPIC is in kernel, Qemu uses this interface to
inject MSIs only (see kvm_apic_mem_write() in hw/i386/kvm/apic.c). This
somehow works with disabled lAPIC but when we're in xAPIC mode we will
get a real injected MSI from every write to lAPIC. Not good.

The simplest solution seems to be to just ignore writes to the region
and return ~0 for all reads when we're in x2APIC mode. This is what this
patch does. However, this approach is inconsistent with what currently
happens when flexpriority is enabled: we allocate APIC access page and
create KVM memory region so in x2APIC modes all reads and writes go to
this pre-allocated page which is, btw, the same for all vCPUs.
Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
      d1766202
  3. 18 Sep, 2018 2 commits
  5. 16 Sep, 2018 2 commits
  7. 15 Sep, 2018 8 commits
  9. 14 Sep, 2018 11 commits
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