From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 2/4] KVM: nSVM: do not forward NMI window singlestep VM exits to L1 Date: Mon, 19 Jun 2017 19:17:10 +0200 Message-ID: References: <20170615112032.15812-1-lprosek@redhat.com> <20170615112032.15812-3-lprosek@redhat.com> <20170616132648.GF2224@potion> <20170619161740.GA13549@potion> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: KVM list To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Ladi Prosek Return-path: Received: from mail-wm0-f46.google.com ([74.125.82.46]:35164 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750878AbdFSRRO (ORCPT ); Mon, 19 Jun 2017 13:17:14 -0400 Received: by mail-wm0-f46.google.com with SMTP id x70so82487006wme.0 for ; Mon, 19 Jun 2017 10:17:14 -0700 (PDT) In-Reply-To: <20170619161740.GA13549@potion> Content-Language: en-US Sender: kvm-owner@vger.kernel.org List-ID: On 19/06/2017 18:17, Radim Krčmář wrote: > Right, we only need the single step over IRET and interrupt shadow. > > Btw. instead of single-stepping over IRET/interrupt shadow, could we set > INTERRUPT_SHADOW in VMCB, inject the NMI, and let it execute? > This mechanism would explain why AMD didn't provide a trap for IRET ... You mean they didn't provide a trap-like VMEXIT for IRET, only fault-like? Thanks, Paolo > APM 15.20 says "Injected events are treated in every way as though they > had occurred normally in the guest", which makes me think that > INTERRUPT_SHADOW blocks them, if it blocks NMIs at all on AMD.