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KVM: x86/hyperv: Assert vCPU's mutex is held in to_hv_vcpu()

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Assert that either vcpu->mutex is held or the VM is otherwise unreachable
when using the normal vCPU => HyperV accessor to help detect improper
cross-task usage of the HyperV structure.  When accessing the structure
without holding the vCPU's mutex, e.g. to send interrupts or to queue TLB
flushes, KVM needs to use the more paranoid to_hv_vcpu_safe() to guarantee
that it can't see a half-baked structure.

To avoid false positives, open code accesses to vcpu->arch.hyperv in the
Synthetic Timer callbacks (can be reached if and only if HyperV state is
fully initialized).

Link: https://patch.msgid.link/20260630225619.511632-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-06-30 15:56:17 -07:00
parent c33aef5817
commit 53ce2c773f
2 changed files with 4 additions and 4 deletions
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6
arch/x86/kvm/hyperv.c
View File

@ -599,8 +599,7 @@ static void stimer_mark_pending(struct kvm_vcpu_hv_stimer *stimer,
{
struct kvm_vcpu *vcpu = hv_stimer_to_vcpu(stimer);
set_bit(stimer->index,
to_hv_vcpu(vcpu)->stimer_pending_bitmap);
set_bit(stimer->index, vcpu->arch.hyperv->stimer_pending_bitmap);
kvm_make_request(KVM_REQ_HV_STIMER, vcpu);
if (vcpu_kick)
kvm_vcpu_kick(vcpu);
@ -614,8 +613,7 @@ static void stimer_cleanup(struct kvm_vcpu_hv_stimer *stimer)
stimer->index);
hrtimer_cancel(&stimer->timer);
clear_bit(stimer->index,
to_hv_vcpu(vcpu)->stimer_pending_bitmap);
clear_bit(stimer->index, vcpu->arch.hyperv->stimer_pending_bitmap);
stimer->msg_pending = false;
stimer->exp_time = 0;
}

2
arch/x86/kvm/hyperv.h
View File

@ -76,6 +76,8 @@ static inline struct kvm_vcpu_hv *to_hv_vcpu_safe(struct kvm_vcpu *vcpu)
static inline struct kvm_vcpu_hv *to_hv_vcpu(struct kvm_vcpu *vcpu)
{
kvm_lockdep_assert_vcpu_is_locked_or_unreachable(vcpu);
return vcpu->arch.hyperv;
}