From:   Wanpeng Li <kernellwp@gmail.com>
To:     linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>
Subject: [PATCH] KVM: SEV: Add lock subtyping in sev_lock_two_vms so lockdep doesn't report false dependencies
Date:   Tue,  4 Jan 2022 22:41:03 -0800
Message-Id: <1641364863-26331-1-git-send-email-wanpengli@tencent.com>
Precedence: bulk

From: Wanpeng Li <wanpengli@tencent.com>

Both source and dest vms' kvm->locks are held in sev_lock_two_vms, 
we should mark one with different subtype to avoid false positives 
from lockdep.

Fixes: c9d61dcb0bc26 (KVM: SEV: accept signals in sev_lock_two_vms)
Reported-by: Yiru Xu <xyru1999@gmail.com>
Tested-by: Jinrong Liang <cloudliang@tencent.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
 arch/x86/kvm/svm/sev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 7656a2c..be28831 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1565,7 +1565,7 @@ static int sev_lock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm)
 	r = -EINTR;
 	if (mutex_lock_killable(&dst_kvm->lock))
 		goto release_src;
-	if (mutex_lock_killable(&src_kvm->lock))
+	if (mutex_lock_killable_nested(&src_kvm->lock, SINGLE_DEPTH_NESTING))
 		goto unlock_dst;
 	return 0;
 
-- 
2.7.4