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  1. 14 9月, 2019 1 次提交
  3. 12 9月, 2019 1 次提交
    • L
      KVM: x86: Fix INIT signal handling in various CPU states · 4b9852f4
      由 Liran Alon 提交于 
      Commit cd7764fe ("KVM: x86: latch INITs while in system management mode")
changed code to latch INIT while vCPU is in SMM and process latched INIT
when leaving SMM. It left a subtle remark in commit message that similar
treatment should also be done while vCPU is in VMX non-root-mode.

However, INIT signals should actually be latched in various vCPU states:
(*) For both Intel and AMD, INIT signals should be latched while vCPU
is in SMM.
(*) For Intel, INIT should also be latched while vCPU is in VMX
operation and later processed when vCPU leaves VMX operation by
executing VMXOFF.
(*) For AMD, INIT should also be latched while vCPU runs with GIF=0
or in guest-mode with intercept defined on INIT signal.

To fix this:
1) Add kvm_x86_ops->apic_init_signal_blocked() such that each CPU vendor
can define the various CPU states in which INIT signals should be
blocked and modify kvm_apic_accept_events() to use it.
2) Modify vmx_check_nested_events() to check for pending INIT signal
while vCPU in guest-mode. If so, emualte vmexit on
EXIT_REASON_INIT_SIGNAL. Note that nSVM should have similar behaviour
but is currently left as a TODO comment to implement in the future
because nSVM don't yet implement svm_check_nested_events().

Note: Currently KVM nVMX implementation don't support VMX wait-for-SIPI
activity state as specified in MSR_IA32_VMX_MISC bits 6:8 exposed to
guest (See nested_vmx_setup_ctls_msrs()).
If and when support for this activity state will be implemented,
kvm_check_nested_events() would need to avoid emulating vmexit on
INIT signal in case activity-state is wait-for-SIPI. In addition,
kvm_apic_accept_events() would need to be modified to avoid discarding
SIPI in case VMX activity-state is wait-for-SIPI but instead delay
SIPI processing to vmx_check_nested_events() that would clear
pending APIC events and emulate vmexit on SIPI.
Reviewed-by: NJoao Martins <joao.m.martins@oracle.com>
Co-developed-by: NNikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: NNikita Leshenko <nikita.leshchenko@oracle.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      4b9852f4
  5. 11 9月, 2019 3 次提交
    • S
      KVM: nVMX: trace nested VM-Enter failures detected by H/W · 380e0055
      由 Sean Christopherson 提交于 
      Use the recently added tracepoint for logging nested VM-Enter failures
instead of spamming the kernel log when hardware detects a consistency
check failure.  Take the opportunity to print the name of the error code
instead of dumping the raw hex number, but limit the symbol table to
error codes that can reasonably be encountered by KVM.

Add an equivalent tracepoint in nested_vmx_check_vmentry_hw(), e.g. so
that tracing of "invalid control field" errors isn't suppressed when
nested early checks are enabled.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      380e0055
    • S
      KVM: nVMX: add tracepoint for failed nested VM-Enter · 5497b955
      由 Sean Christopherson 提交于 
      Debugging a failed VM-Enter is often like searching for a needle in a
haystack, e.g. there are over 80 consistency checks that funnel into
the "invalid control field" error code.  One way to expedite debug is
to run the buggy code as an L1 guest under KVM (and pray that the
failing check is detected by KVM).  However, extracting useful debug
information out of L0 KVM requires attaching a debugger to KVM and/or
modifying the source, e.g. to log which check is failing.

Make life a little less painful for VMM developers and add a tracepoint
for failed VM-Enter consistency checks.  Ideally the tracepoint would
capture both what check failed and precisely why it failed, but logging
why a checked failed is difficult to do in a generic tracepoint without
resorting to invasive techniques, e.g. generating a custom string on
failure.  That being said, for the vast majority of VM-Enter failures
the most difficult step is figuring out exactly what to look at, e.g.
figuring out which bit was incorrectly set in a control field is usually
not too painful once the guilty field as been identified.

To reach a happy medium between precision and ease of use, simply log
the code that detected a failed check, using a macro to execute the
check and log the trace event on failure.  This approach enables tracing
arbitrary code, e.g. it's not limited to function calls or specific
formats of checks, and the changes to the existing code are minimally
invasive.  A macro with a two-character name is desirable as usage of
the macro doesn't result in overly long lines or confusing alignment,
while still retaining some amount of readability.  I.e. a one-character
name is a little too terse, and a three-character name results in the
contents being passed to the macro aligning with an indented line when
the macro is used an in if-statement, e.g.:

        if (VCC(nested_vmx_check_long_line_one(...) &&
                nested_vmx_check_long_line_two(...)))
                return -EINVAL;

And that is the story of how the CC(), a.k.a. Consistency Check, macro
got its name.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      5497b955
    • S
      KVM: x86: Refactor up kvm_{g,s}et_msr() to simplify callers · f20935d8
      由 Sean Christopherson 提交于 
      Refactor the top-level MSR accessors to take/return the index and value
directly instead of requiring the caller to dump them into a msr_data
struct.

No functional change intended.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      f20935d8
  7. 22 7月, 2019 2 次提交
  9. 20 7月, 2019 1 次提交
  11. 16 7月, 2019 1 次提交
  13. 05 7月, 2019 2 次提交
    • K
      KVM nVMX: Check Host Segment Registers and Descriptor Tables on vmentry of nested guests · 1ef23e1f
      由 Krish Sadhukhan 提交于 
      According to section "Checks on Host Segment and Descriptor-Table
Registers" in Intel SDM vol 3C, the following checks are performed on
vmentry of nested guests:

   - In the selector field for each of CS, SS, DS, ES, FS, GS and TR, the
     RPL (bits 1:0) and the TI flag (bit 2) must be 0.
   - The selector fields for CS and TR cannot be 0000H.
   - The selector field for SS cannot be 0000H if the "host address-space
     size" VM-exit control is 0.
   - On processors that support Intel 64 architecture, the base-address
     fields for FS, GS and TR must contain canonical addresses.
Signed-off-by: NKrish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: NKarl Heubaum <karl.heubaum@oracle.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      1ef23e1f
    • S
      KVM: nVMX: Stash L1's CR3 in vmcs01.GUEST_CR3 on nested entry w/o EPT · f087a029
      由 Sean Christopherson 提交于 
      KVM does not have 100% coverage of VMX consistency checks, i.e. some
checks that cause VM-Fail may only be detected by hardware during a
nested VM-Entry.  In such a case, KVM must restore L1's state to the
pre-VM-Enter state as L2's state has already been loaded into KVM's
software model.

L1's CR3 and PDPTRs in particular are loaded from vmcs01.GUEST_*.  But
when EPT is disabled, the associated fields hold KVM's shadow values,
not L1's "real" values.  Fortunately, when EPT is disabled the PDPTRs
come from memory, i.e. are not cached in the VMCS.  Which leaves CR3
as the sole anomaly.

A previously applied workaround to handle CR3 was to force nested early
checks if EPT is disabled:

  commit 2b27924b ("KVM: nVMX: always use early vmcs check when EPT
                         is disabled")

Forcing nested early checks is undesirable as doing so adds hundreds of
cycles to every nested VM-Entry.  Rather than take this performance hit,
handle CR3 by overwriting vmcs01.GUEST_CR3 with L1's CR3 during nested
VM-Entry when EPT is disabled *and* nested early checks are disabled.
By stuffing vmcs01.GUEST_CR3, nested_vmx_restore_host_state() will
naturally restore the correct vcpu->arch.cr3 from vmcs01.GUEST_CR3.

These shenanigans work because nested_vmx_restore_host_state() does a
full kvm_mmu_reset_context(), i.e. unloads the current MMU, which
guarantees vmcs01.GUEST_CR3 will be rewritten with a new shadow CR3
prior to re-entering L1.

vcpu->arch.root_mmu.root_hpa is set to INVALID_PAGE via:

    nested_vmx_restore_host_state() ->
        kvm_mmu_reset_context() ->
            kvm_mmu_unload() ->
                kvm_mmu_free_roots()

kvm_mmu_unload() has WARN_ON(root_hpa != INVALID_PAGE), i.e. we can bank
on 'root_hpa == INVALID_PAGE' unless the implementation of
kvm_mmu_reset_context() is changed.

On the way into L1, VMCS.GUEST_CR3 is guaranteed to be written (on a
successful entry) via:

    vcpu_enter_guest() ->
        kvm_mmu_reload() ->
            kvm_mmu_load() ->
                kvm_mmu_load_cr3() ->
                    vmx_set_cr3()

Stuff vmcs01.GUEST_CR3 if and only if nested early checks are disabled
as a "late" VM-Fail should never happen win that case (KVM WARNs), and
the conditional write avoids the need to restore the correct GUEST_CR3
when nested_vmx_check_vmentry_hw() fails.
Signed-off-by: NSean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20190607185534.24368-1-sean.j.christopherson@intel.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      f087a029
  15. 03 7月, 2019 5 次提交
    • L
      KVM: nVMX: Change KVM_STATE_NESTED_EVMCS to signal vmcs12 is copied from eVMCS · 323d73a8
      由 Liran Alon 提交于 
      Currently KVM_STATE_NESTED_EVMCS is used to signal that eVMCS
capability is enabled on vCPU.
As indicated by vmx->nested.enlightened_vmcs_enabled.

This is quite bizarre as userspace VMM should make sure to expose
same vCPU with same CPUID values in both source and destination.
In case vCPU is exposed with eVMCS support on CPUID, it is also
expected to enable KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability.
Therefore, KVM_STATE_NESTED_EVMCS is redundant.

KVM_STATE_NESTED_EVMCS is currently used on restore path
(vmx_set_nested_state()) only to enable eVMCS capability in KVM
and to signal need_vmcs12_sync such that on next VMEntry to guest
nested_sync_from_vmcs12() will be called to sync vmcs12 content
into eVMCS in guest memory.
However, because restore nested-state is rare enough, we could
have just modified vmx_set_nested_state() to always signal
need_vmcs12_sync.

From all the above, it seems that we could have just removed
the usage of KVM_STATE_NESTED_EVMCS. However, in order to preserve
backwards migration compatibility, we cannot do that.
(vmx_get_nested_state() needs to signal flag when migrating from
new kernel to old kernel).

Returning KVM_STATE_NESTED_EVMCS when just vCPU have eVMCS enabled
have a bad side-effect of userspace VMM having to send nested-state
from source to destination as part of migration stream. Even if
guest have never used eVMCS as it doesn't even run a nested
hypervisor workload. This requires destination userspace VMM and
KVM to support setting nested-state. Which make it more difficult
to migrate from new host to older host.
To avoid this, change KVM_STATE_NESTED_EVMCS to signal eVMCS is
not only enabled but also active. i.e. Guest have made some
eVMCS active via an enlightened VMEntry. i.e. vmcs12 is copied
from eVMCS and therefore should be restored into eVMCS resident
in memory (by copy_vmcs12_to_enlightened()).
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NMaran Wilson <maran.wilson@oracle.com>
Reviewed-by: NKrish Sadhukhan <krish.sadhukhan@oracle.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      323d73a8
    • L
      KVM: nVMX: Allow restore nested-state to enable eVMCS when vCPU in SMM · 65b712f1
      由 Liran Alon 提交于 
      As comment in code specifies, SMM temporarily disables VMX so we cannot
be in guest mode, nor can VMLAUNCH/VMRESUME be pending.

However, code currently assumes that these are the only flags that can be
set on kvm_state->flags. This is not true as KVM_STATE_NESTED_EVMCS
can also be set on this field to signal that eVMCS should be enabled.

Therefore, fix code to check for guest-mode and pending VMLAUNCH/VMRESUME
explicitly.
Reviewed-by: NJoao Martins <joao.m.martins@oracle.com>
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      65b712f1
    • J
      kvm: nVMX: Remove unnecessary sync_roots from handle_invept · b1190198
      由 Jim Mattson 提交于 
      When L0 is executing handle_invept(), the TDP MMU is active. Emulating
an L1 INVEPT does require synchronizing the appropriate shadow EPT
root(s), but a call to kvm_mmu_sync_roots in this context won't do
that. Similarly, the hardware TLB and paging-structure-cache entries
associated with the appropriate shadow EPT root(s) must be flushed,
but requesting a TLB_FLUSH from this context won't do that either.

How did this ever work? KVM always does a sync_roots and TLB flush (in
the correct context) when transitioning from L1 to L2. That isn't the
best choice for nested VM performance, but it effectively papers over
the mistakes here.

Remove the unnecessary operations and leave a comment to try to do
better in the future.
Reported-by: NJunaid Shahid <junaids@google.com>
Fixes: bfd0a56b ("nEPT: Nested INVEPT")
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Nadav Har'El <nyh@il.ibm.com>
Cc: Jun Nakajima <jun.nakajima@intel.com>
Cc: Xinhao Xu <xinhao.xu@intel.com>
Cc: Yang Zhang <yang.z.zhang@Intel.com>
Cc: Gleb Natapov <gleb@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by Peter Shier <pshier@google.com>
Reviewed-by: NJunaid Shahid <junaids@google.com>
Signed-off-by: NJim Mattson <jmattson@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      b1190198
    • V
      x86/kvm/nVMX: fix VMCLEAR when Enlightened VMCS is in use · 11e34914
      由 Vitaly Kuznetsov 提交于 
      When Enlightened VMCS is in use, it is valid to do VMCLEAR and,
according to TLFS, this should "transition an enlightened VMCS from the
active to the non-active state". It is, however, wrong to assume that
it is only valid to do VMCLEAR for the eVMCS which is currently active
on the vCPU performing VMCLEAR.

Currently, the logic in handle_vmclear() is broken: in case, there is no
active eVMCS on the vCPU doing VMCLEAR we treat the argument as a 'normal'
VMCS and kvm_vcpu_write_guest() to the 'launch_state' field irreversibly
corrupts the memory area.

So, in case the VMCLEAR argument is not the current active eVMCS on the
vCPU, how can we know if the area it is pointing to is a normal or an
enlightened VMCS?
Thanks to the bug in Hyper-V (see commit 72aeb60c ("KVM: nVMX: Verify
eVMCS revision id match supported eVMCS version on eVMCS VMPTRLD")) we can
not, the revision can't be used to distinguish between them. So let's
assume it is always enlightened in case enlightened vmentry is enabled in
the assist page. Also, check if vmx->nested.enlightened_vmcs_enabled to
minimize the impact for 'unenlightened' workloads.

Fixes: b8bbab92 ("KVM: nVMX: implement enlightened VMPTRLD and VMCLEAR")
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      11e34914
    • V
      x86/KVM/nVMX: don't use clean fields data on enlightened VMLAUNCH · a21a39c2
      由 Vitaly Kuznetsov 提交于 
      Apparently, Windows doesn't maintain clean fields data after it does
VMCLEAR for an enlightened VMCS so we can only use it on VMRESUME.
The issue went unnoticed because currently we do nested_release_evmcs()
in handle_vmclear() and the consecutive enlightened VMPTRLD invalidates
clean fields when a new eVMCS is mapped but we're going to change the
logic.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      a21a39c2
  17. 02 7月, 2019 2 次提交
  19. 21 6月, 2019 1 次提交
    • P
      KVM: nVMX: reorganize initial steps of vmx_set_nested_state · 9fd58877
      由 Paolo Bonzini 提交于 
      Commit 332d0797 ("KVM: nVMX: KVM_SET_NESTED_STATE - Tear down old EVMCS
state before setting new state", 2019-05-02) broke evmcs_test because the
eVMCS setup must be performed even if there is no VMXON region defined,
as long as the eVMCS bit is set in the assist page.

While the simplest possible fix would be to add a check on
kvm_state->flags & KVM_STATE_NESTED_EVMCS in the initial "if" that
covers kvm_state->hdr.vmx.vmxon_pa == -1ull, that is quite ugly.

Instead, this patch moves checks earlier in the function and
conditionalizes them on kvm_state->hdr.vmx.vmxon_pa, so that
vmx_set_nested_state always goes through vmx_leave_nested
and nested_enable_evmcs.

Fixes: 332d0797 ("KVM: nVMX: KVM_SET_NESTED_STATE - Tear down old EVMCS state before setting new state")
Cc: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      9fd58877
  21. 19 6月, 2019 1 次提交
    • L
      KVM: x86: Modify struct kvm_nested_state to have explicit fields for data · 6ca00dfa
      由 Liran Alon 提交于 
      Improve the KVM_{GET,SET}_NESTED_STATE structs by detailing the format
of VMX nested state data in a struct.

In order to avoid changing the ioctl values of
KVM_{GET,SET}_NESTED_STATE, there is a need to preserve
sizeof(struct kvm_nested_state). This is done by defining the data
struct as "data.vmx[0]". It was the most elegant way I found to
preserve struct size while still keeping struct readable and easy to
maintain. It does have a misfortunate side-effect that now it has to be
accessed as "data.vmx[0]" rather than just "data.vmx".

Because we are already modifying these structs, I also modified the
following:
* Define the "format" field values as macros.
* Rename vmcs_pa to vmcs12_pa for better readability.
Signed-off-by: NLiran Alon <liran.alon@oracle.com>
[Remove SVM stubs, add KVM_STATE_NESTED_VMX_VMCS12_SIZE. - Paolo]
Reviewed-by: NLiran Alon <liran.alon@oracle.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
      6ca00dfa
  23. 18 6月, 2019 20 次提交