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([2001:b07:6468:f312:ec9b:111a:97e3:4baf]) by smtp.gmail.com with ESMTPSA id a15sm4540071wrn.3.2020.09.25.14.05.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 25 Sep 2020 14:05:50 -0700 (PDT) Subject: Re: [RFC PATCH 0/3] KVM: Introduce "VM bugged" concept To: Marc Zyngier , Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, James Morse , Julien Thierry , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Huacai Chen , Aleksandar Markovic , linux-mips@vger.kernel.org, Paul Mackerras , kvm-ppc@vger.kernel.org, Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Claudio Imbrenda References: <20200923224530.17735-1-sean.j.christopherson@intel.com> <874knlrf4a.wl-maz@kernel.org> From: Paolo Bonzini Message-ID: <100a603f-193c-5a46-d428-cfc0ce0a8fe4@redhat.com> Date: Fri, 25 Sep 2020 23:05:48 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <874knlrf4a.wl-maz@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On 25/09/20 18:32, Marc Zyngier wrote: > I'm quite like the idea. However, I wonder whether preventing the > vcpus from re-entering the guest is enough. When something goes really > wrong, is it safe to allow the userspace process to terminate normally > and free the associated memory? And is it still safe to allow new VMs > to be started? For something that bad, where e.g. you can't rule out future memory corruptions via use-after-free bugs or similar, you're probably entering BUG_ON territory. Paolo