From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 2/4] KVM: nSVM: propagate the NPF EXITINFO to the guest Date: Tue, 02 Sep 2014 19:01:21 +0200 Message-ID: <5405F7E1.1090505@redhat.com> References: <1409670830-14544-1-git-send-email-pbonzini@redhat.com> <1409670830-14544-3-git-send-email-pbonzini@redhat.com> <20140902163344.GB16722@suse.de> <5405F44E.7090803@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, agraf@suse.de, valentine.sinitsyn@gmail.com, jan.kiszka@siemens.com, gleb@cloudius-systems.com, avi@cloudius-systems.com To: Joerg Roedel Return-path: In-Reply-To: <5405F44E.7090803@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Il 02/09/2014 18:46, Paolo Bonzini ha scritto: >> > How about an io-port emulated on >> > L1 but passed through to L2 by the nested hypervisor. On emulation of >> > INS or OUTS, KVM would need to read/write to an L2 address space, > It would need to read/write to *L1* (that's where the VMCB's IOIO map > lies), which could result into a regular page fault injected into L1. Nevermind, the VMCB's IO bitmap is a guest physical address. I see what you mean now. nested_svm_intercept_ioio would return NESTED_EXIT_HOST and proceed to emulate the read/write. This could indeed cause a NPF. For now I'll remove the WARN_ON. Paolo