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AJvYcCUtVU3jwWjhcRsFb3zuCjz0vJxnzjyNUB24xkWS6jC938gJyh8kl0FN55cjA/zSs6ZHSXk=@vger.kernel.org X-Gm-Message-State: AOJu0YyCsdRAijqWQPB0FA+zGmXiIXE15UC5cftssfK33t8sbmEqA5// 0KIFR4T9ehUu1C36wjcbpCCRvIhvEUbNMSsfsQrxgB9znbhNwFYop7rHzZgcxtI6NT289A/YPqF /tA== X-Google-Smtp-Source: AGHT+IGxB0koQk+4DjbniMid//s+el+4YQz2SWzY87trrY9JIa/Nx1bMlTC4pMlfqu9yuRVU/vSNoPRCjB8= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:903:2352:b0:205:799f:124f with SMTP id d9443c01a7336-205799f1586mr8750175ad.5.1725490165129; Wed, 04 Sep 2024 15:49:25 -0700 (PDT) Date: Wed, 4 Sep 2024 15:49:23 -0700 In-Reply-To: <20240904210830.GA1229985@thelio-3990X> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240720000138.3027780-1-seanjc@google.com> <20240720000138.3027780-2-seanjc@google.com> <20240904210830.GA1229985@thelio-3990X> Message-ID: Subject: Re: [PATCH 1/6] KVM: nVMX: Get to-be-acknowledge IRQ for nested VM-Exit at injection site From: Sean Christopherson To: Nathan Chancellor Cc: Paolo Bonzini , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Gao , Zeng Guang Content-Type: text/plain; charset="us-ascii" On Wed, Sep 04, 2024, Nathan Chancellor wrote: > I bisected (log below) an issue with starting a nested guest that > appears on two of my newer Intel test machines (but not a somewhat old > laptop) when this change as commit 6f373f4d941b ("KVM: nVMX: Get > to-be-acknowledge IRQ for nested VM-Exit at injection site") in -next is > present in the host kernel. > > I start a virtual machine with a full distribution using QEMU then start > a nested virtual machine using QEMU with the same kernel and a much > simpler Buildroot initrd, just to test the ability to run a nested > guest. After this change, starting a nested guest results in no output > from the nested guest and eventually the first guest restarts, sometimes > printing a lockup message that appears to be caused from qemu-system-x86 *sigh* It's not you, it's me. I just bisected hangs in my nested setup to this same commit. Apparently, I completely and utterly failed at testing. There isn't that much going on here, so knock wood, getting a root cause shouldn't be terribly difficult.