Commit 2d089356 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86: Don't re-acquire SRCU lock in complete_emulated_io() 



Don't re-acquire SRCU in complete_emulated_io() now that KVM acquires the
lock in kvm_arch_vcpu_ioctl_run().  More importantly, don't overwrite
vcpu->srcu_idx.  If the index acquired by complete_emulated_io() differs
from the one acquired by kvm_arch_vcpu_ioctl_run(), KVM will effectively
leak a lock and hang if/when synchronize_srcu() is invoked for the
relevant grace period.

Fixes: 8d25b7be ("KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220415004343.2203171-2-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 012c7225

arch/x86/kvm/x86.c

+1 −6
Original line number Diff line number Diff line
@@ -10387,12 +10387,7 @@ static int vcpu_run(struct kvm_vcpu *vcpu) 


static inline int complete_emulated_io(struct kvm_vcpu *vcpu)

{

	int r;



	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);

	r = kvm_emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);

	return r;

	return kvm_emulate_instruction(vcpu, EMULTYPE_NO_DECODE);

}



static int complete_emulated_pio(struct kvm_vcpu *vcpu)