kvm_make_vcpus_request_mask() already disables preemption so just like
kvm_make_all_cpus_request_except() it can be switched to using
pre-allocated per-cpu cpumasks. This allows for improvements for both
users of the function: in Hyper-V emulation code 'tlb_flush' can now be
dropped from 'struct kvm_vcpu_hv' and kvm_make_scan_ioapic_request_mask()
gets rid of dynamic allocation.

cpumask_available() checks in kvm_make_vcpu_request() and
kvm_kick_many_cpus() can now be dropped as they checks for an impossible
condition: kvm_init() makes sure per-cpu masks are allocated.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-9-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Both remaining callers of kvm_make_vcpus_request_mask() pass 'NULL' for
'except' parameter so it can just be dropped.

No functional change intended ©.
Suggested-by: NSean Christopherson <seanjc@google.com>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-6-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In preparation to making kvm_make_vcpus_request_mask() use for_each_set_bit()
switch kvm_hv_flush_tlb() to calling kvm_make_all_cpus_request() for 'all cpus'
case.

Note: kvm_make_all_cpus_request() (unlike kvm_make_vcpus_request_mask())
currently dynamically allocates cpumask on each call and this is suboptimal.
Both kvm_make_all_cpus_request() and kvm_make_vcpus_request_mask() are
going to be switched to using pre-allocated per-cpu masks.
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210903075141.403071-4-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Read vcpu->vcpu_idx directly instead of bouncing through the one-line
wrapper, kvm_vcpu_get_idx(), and drop the wrapper.  The wrapper is a
remnant of the original implementation and serves no purpose; remove it
before it gains more users.

Back when kvm_vcpu_get_idx() was added by commit 497d72d8 ("KVM: Add
kvm_vcpu_get_idx to get vcpu index in kvm->vcpus"), the implementation
was more than just a simple wrapper as vcpu->vcpu_idx did not exist and
retrieving the index meant walking over the vCPU array to find the given
vCPU.

When vcpu_idx was introduced by commit 8750e72a ("KVM: remember
position in kvm->vcpus array"), the helper was left behind, likely to
avoid extra thrash (but even then there were only two users, the original
arm usage having been removed at some point in the past).

No functional change intended.
Suggested-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NSean Christopherson <seanjc@google.com>
Reviewed-by: NMaxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20210910183220.2397812-2-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

APICV_INHIBIT_REASON_HYPERV is currently unconditionally forced upon
SynIC activation as SynIC's AutoEOI is incompatible with APICv/AVIC. It is,
however, possible to track whether the feature was actually used by the
guest and only inhibit APICv/AVIC when needed.

TLFS suggests a dedicated 'HV_DEPRECATING_AEOI_RECOMMENDED' flag to let
Windows know that AutoEOI feature should be avoided. While it's up to
KVM userspace to set the flag, KVM can help a bit by exposing global
APICv/AVIC enablement.

Maxim:
   - always set HV_DEPRECATING_AEOI_RECOMMENDED in kvm_get_hv_cpuid,
     since this feature can be used regardless of AVIC

Paolo:
   - use arch.apicv_update_lock to protect the hv->synic_auto_eoi_used
     instead of atomic ops
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210810205251.424103-12-mlevitsk@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

hv_vcpu is initialized again a dozen lines below, and at this
point vcpu->arch.hyperv is not valid.  Remove the initializer.
Reported-by: Nkernel test robot <lkp@intel.com>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

TLFS states that "Availability of the XMM fast hypercall interface is
indicated via the “Hypervisor Feature Identification” CPUID Leaf
(0x40000003, see section 2.4.4) ... Any attempt to use this interface
when the hypervisor does not indicate availability will result in a #UD
fault."

Implement the check for 'strict' mode (KVM_CAP_HYPERV_ENFORCE_CPUID).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210730122625.112848-4-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hypercall failures are unusual with potentially far going consequences
so it would be useful to see their results when tracing.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210730122625.112848-3-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

In case guest doesn't have access to the particular hypercall we can avoid
reading XMM registers.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210730122625.112848-2-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Trigger a full TLB flush on behalf of the guest on nested VM-Enter and
VM-Exit when VPID is disabled for L2.  kvm_mmu_new_pgd() syncs only the
current PGD, which can theoretically leave stale, unsync'd entries in a
previous guest PGD, which could be consumed if L2 is allowed to load CR3
with PCID_NOFLUSH=1.

Rename KVM_REQ_HV_TLB_FLUSH to KVM_REQ_TLB_FLUSH_GUEST so that it can
be utilized for its obvious purpose of emulating a guest TLB flush.

Note, there is no change the actual TLB flush executed by KVM, even
though the fast PGD switch uses KVM_REQ_TLB_FLUSH_CURRENT.  When VPID is
disabled for L2, vpid02 is guaranteed to be '0', and thus
nested_get_vpid02() will return the VPID that is shared by L1 and L2.

Generate the request outside of kvm_mmu_new_pgd(), as getting the common
helper to correctly identify which requested is needed is quite painful.
E.g. using KVM_REQ_TLB_FLUSH_GUEST when nested EPT is in play is wrong as
a TLB flush from the L1 kernel's perspective does not invalidate EPT
mappings.  And, by using KVM_REQ_TLB_FLUSH_GUEST, nVMX can do future
simplification by moving the logic into nested_vmx_transition_tlb_flush().

Fixes: 41fab65e ("KVM: nVMX: Skip MMU sync on nested VMX transition when possible")
Signed-off-by: NSean Christopherson <seanjc@google.com>
Message-Id: <20210609234235.1244004-2-seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hypercalls which use extended processor masks are only available when
HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED privilege bit is exposed (and
'RECOMMENDED' is rather a misnomer).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-28-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V partition must possess 'HV_X64_CLUSTER_IPI_RECOMMENDED'
privilege ('recommended' is rather a misnomer) to issue
HVCALL_SEND_IPI hypercalls.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-27-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V partition must possess 'HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED'
privilege ('recommended' is rather a misnomer) to issue
HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST/SPACE hypercalls.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-26-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V partition must possess 'HV_DEBUGGING' privilege to issue
HVCALL_POST_DEBUG_DATA/HVCALL_RETRIEVE_DEBUG_DATA/
HVCALL_RESET_DEBUG_SESSION hypercalls.

Note, when SynDBG is disabled hv_check_hypercall_access() returns
'true' (like for any other unknown hypercall) so the result will
be HV_STATUS_INVALID_HYPERCALL_CODE and not HV_STATUS_ACCESS_DENIED.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-25-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V partition must possess 'HV_SIGNAL_EVENTS' privilege to issue
HVCALL_SIGNAL_EVENT hypercalls.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-24-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V partition must possess 'HV_POST_MESSAGES' privilege to issue
HVCALL_POST_MESSAGE hypercalls.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-23-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

TLFS6.0b states that partition issuing HVCALL_NOTIFY_LONG_SPIN_WAIT must
posess 'UseHypercallForLongSpinWait' privilege but there's no
corresponding feature bit. Instead, we have "Recommended number of attempts
to retry a spinlock failure before notifying the hypervisor about the
failures. 0xFFFFFFFF indicates never notify." Use this to check access to
the hypercall. Also, check against zero as the corresponding CPUID must
be set (and '0' attempts before re-try is weird anyway).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-22-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Introduce hv_check_hypercallr_access() to check if the particular hypercall
should be available to guest, this will be used with
KVM_CAP_HYPERV_ENFORCE_CPUID mode.

No functional change intended.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-21-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Synthetic timers can only be configured in 'direct' mode when
HV_STIMER_DIRECT_MODE_AVAILABLE bit was exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-20-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Access to all MSRs is now properly checked. To avoid 'forgetting' to
properly check access to new MSRs in the future change the default
to 'false' meaning 'no access'.

No functional change intended.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-19-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Synthetic debugging MSRs (HV_X64_MSR_SYNDBG_CONTROL,
HV_X64_MSR_SYNDBG_STATUS, HV_X64_MSR_SYNDBG_SEND_BUFFER,
HV_X64_MSR_SYNDBG_RECV_BUFFER, HV_X64_MSR_SYNDBG_PENDING_BUFFER,
HV_X64_MSR_SYNDBG_OPTIONS) are only available to guest when
HV_FEATURE_DEBUG_MSRS_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-18-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_CRASH_P0 ... HV_X64_MSR_CRASH_P4, HV_X64_MSR_CRASH_CTL are only
available to guest when HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE bit is
exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-17-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_REENLIGHTENMENT_CONTROL/HV_X64_MSR_TSC_EMULATION_CONTROL/
HV_X64_MSR_TSC_EMULATION_STATUS are only available to guest when
HV_ACCESS_REENLIGHTENMENT bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-16-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_TSC_FREQUENCY/HV_X64_MSR_APIC_FREQUENCY are only available to
guest when HV_ACCESS_FREQUENCY_MSRS bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-15-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_EOI, HV_X64_MSR_ICR, HV_X64_MSR_TPR, and
HV_X64_MSR_VP_ASSIST_PAGE  are only available to guest when
HV_MSR_APIC_ACCESS_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-14-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Synthetic timers MSRs (HV_X64_MSR_STIMER[0-3]_CONFIG,
HV_X64_MSR_STIMER[0-3]_COUNT) are only available to guest when
HV_MSR_SYNTIMER_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-13-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

SynIC MSRs (HV_X64_MSR_SCONTROL, HV_X64_MSR_SVERSION, HV_X64_MSR_SIEFP,
HV_X64_MSR_SIMP, HV_X64_MSR_EOM, HV_X64_MSR_SINT0 ... HV_X64_MSR_SINT15)
are only available to guest when HV_MSR_SYNIC_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-12-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_REFERENCE_TSC is only available to guest when
HV_MSR_REFERENCE_TSC_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-11-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_RESET is only available to guest when HV_MSR_RESET_AVAILABLE bit
is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-10-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_VP_INDEX is only available to guest when
HV_MSR_VP_INDEX_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-9-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_TIME_REF_COUNT is only available to guest when
HV_MSR_TIME_REF_COUNT_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-8-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_VP_RUNTIME is only available to guest when
HV_MSR_VP_RUNTIME_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-7-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

HV_X64_MSR_GUEST_OS_ID/HV_X64_MSR_HYPERCALL are only available to guest
when HV_MSR_HYPERCALL_AVAILABLE bit is exposed.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-6-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Introduce hv_check_msr_access() to check if the particular MSR
should be accessible by guest, this will be used with
KVM_CAP_HYPERV_ENFORCE_CPUID mode.

No functional change intended.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-5-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Limiting exposed Hyper-V features requires a fast way to check if the
particular feature is exposed in guest visible CPUIDs or not. To aboid
looping through all CPUID entries on every hypercall/MSR access cache
the required leaves on CPUID update.
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-4-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Modeled after KVM_CAP_ENFORCE_PV_FEATURE_CPUID, the new capability allows
for limiting Hyper-V features to those exposed to the guest in Hyper-V
CPUIDs (0x40000003, 0x40000004, ...).
Signed-off-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-3-vkuznets@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Now that kvm_hv_flush_tlb() has been patched to support XMM hypercall
inputs, we can start advertising this feature to guests.

Cc: Alexander Graf <graf@amazon.com>
Cc: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Message-Id: <e63fc1c61dd2efecbefef239f4f0a598bd552750.1622019134.git.sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

Hyper-V supports the use of XMM registers to perform fast hypercalls.
This allows guests to take advantage of the improved performance of the
fast hypercall interface even though a hypercall may require more than
(the current maximum of) two input registers.

The XMM fast hypercall interface uses six additional XMM registers (XMM0
to XMM5) to allow the guest to pass an input parameter block of up to
112 bytes.

Add framework to read from XMM registers in kvm_hv_hypercall() and use
the additional hypercall inputs from XMM registers in kvm_hv_flush_tlb()
when possible.

Cc: Alexander Graf <graf@amazon.com>
Co-developed-by: NEvgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: NEvgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Message-Id: <fc62edad33f1920fe5c74dde47d7d0b4275a9012.1622019134.git.sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

As of now there are 7 parameters (and flags) that are used in various
hyper-v hypercall handlers. There are 6 more input/output parameters
passed from XMM registers which are to be added in an upcoming patch.

To make passing arguments to the handlers more readable, capture all
these parameters into a single structure.

Cc: Alexander Graf <graf@amazon.com>
Cc: Evgeny Iakovlev <eyakovl@amazon.de>
Signed-off-by: NSiddharth Chandrasekaran <sidcha@amazon.de>
Message-Id: <273f7ed510a1f6ba177e61b73a5c7bfbee4a4a87.1622019133.git.sidcha@amazon.de>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

   WARNING: suspicious RCU usage
   5.13.0-rc1 #4 Not tainted
   -----------------------------
   ./include/linux/kvm_host.h:710 suspicious rcu_dereference_check() usage!

  other info that might help us debug this:

  rcu_scheduler_active = 2, debug_locks = 1
   1 lock held by hyperv_clock/8318:
    #0: ffffb6b8cb05a7d8 (&hv->hv_lock){+.+.}-{3:3}, at: kvm_hv_invalidate_tsc_page+0x3e/0xa0 [kvm]

  stack backtrace:
  CPU: 3 PID: 8318 Comm: hyperv_clock Not tainted 5.13.0-rc1 #4
  Call Trace:
   dump_stack+0x87/0xb7
   lockdep_rcu_suspicious+0xce/0xf0
   kvm_write_guest_page+0x1c1/0x1d0 [kvm]
   kvm_write_guest+0x50/0x90 [kvm]
   kvm_hv_invalidate_tsc_page+0x79/0xa0 [kvm]
   kvm_gen_update_masterclock+0x1d/0x110 [kvm]
   kvm_arch_vm_ioctl+0x2a7/0xc50 [kvm]
   kvm_vm_ioctl+0x123/0x11d0 [kvm]
   __x64_sys_ioctl+0x3ed/0x9d0
   do_syscall_64+0x3d/0x80
   entry_SYSCALL_64_after_hwframe+0x44/0xae

kvm_memslots() will be called by kvm_write_guest(), so we should take the srcu lock.

Fixes: e880c6ea (KVM: x86: hyper-v: Prevent using not-yet-updated TSC page by secondary CPUs)
Reviewed-by: NVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: NWanpeng Li <wanpengli@tencent.com>
Message-Id: <1621339235-11131-4-git-send-email-wanpengli@tencent.com>
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>