From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 2d08935682ac5f6bfb70f7e6844ec27d4a245fa4 upstream.
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: 8d25b7beca7e ("KVM: x86: pull kvm->srcu read-side to kvm_arch_vcpu_ioctl_run")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Message-Id: <20220415004343.2203171-2-seanjc@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10296,12 +10296,7 @@ static int vcpu_run(struct kvm_vcpu *vcp
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)
