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, 31 May 2016 12:29:31 +0200 Message-ID: <574D678B.6020608@redhat.com> References: <1463598080-27643-1-git-send-email-thuth@redhat.com> <573D7399.9020708@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Cc: Alexander Graf , lvivier@redhat.com, kvm@vger.kernel.org To: Paul Mackerras , kvm-ppc@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:41390 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751023AbcEaK3f (ORCPT ); Tue, 31 May 2016 06:29:35 -0400 In-Reply-To: <573D7399.9020708@suse.de> Sender: kvm-owner@vger.kernel.org List-ID: 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? Thanks, Thomas