From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Huth Subject: Re: [PATCH] KVM: PPC: Fix illegal opcode emulation in kvm-pr Date: Tue, 14 Jun 2016 19:49:48 +0200 Message-ID: <576043BC.4050604@redhat.com> References: <1463598080-27643-1-git-send-email-thuth@redhat.com> <573D7399.9020708@suse.de> <574D678B.6020608@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: lvivier@redhat.com, kvm@vger.kernel.org To: Paul Mackerras , kvm-ppc@vger.kernel.org, Alexander Graf Return-path: Received: from mx1.redhat.com ([209.132.183.28]:33548 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932109AbcFNRtv (ORCPT ); Tue, 14 Jun 2016 13:49:51 -0400 In-Reply-To: <574D678B.6020608@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 31.05.2016 12:29, Thomas Huth wrote: > On 19.05.2016 10:04, Alexander Graf wrote: >> On 05/18/2016 09:01 PM, Thomas Huth wrote: >>> If kvmppc_handle_exit_pr() calls kvmppc_emulate_instruction() to emulate >>> one instruction (in the BOOK3S_INTERRUPT_H_EMUL_ASSIST case), it calls >>> kvmppc_core_queue_program() afterwards if kvmppc_emulate_instruction() >>> returned EMULATE_FAIL, so the guest gets an program interrupt for the >>> illegal opcode. >>> However, the kvmppc_emulate_instruction() also tried to inject a >>> program exception for this already, so the program interrupt gets >>> injected twice and the return address in srr0 gets destroyed. >>> All other callers of kvmppc_emulate_instruction() are also injecting >>> a program interrupt, and since the callers have the right knowledge >>> about the srr1 flags that should be used, it is the function >>> kvmppc_emulate_instruction() that should _not_ inject program >>> interrupts, so remove the kvmppc_core_queue_program() here. >>> >>> This fixes the issue discovered by Laurent Vivier with kvm-unit-tests >>> where the logs are filled with these messages when the test tries >>> to execute an illegal instruction: >>> >>> Couldn't emulate instruction 0x00000000 (op 0 xop 0) >>> kvmppc_handle_exit_pr: emulation at 700 failed (00000000) >>> >>> Signed-off-by: Thomas Huth >> >> I'm surprised you're the first one to encounter this :). >> >> Reviewed-by: Alexander Graf > > *ping* > > Paul, could you maybe pick up this patch? ping^2 Thomas