From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 862A8C433FF for ; Wed, 31 Jul 2019 09:43:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A9F220665 for ; Wed, 31 Jul 2019 09:43:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728768AbfGaJnZ (ORCPT ); Wed, 31 Jul 2019 05:43:25 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41822 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726432AbfGaJnY (ORCPT ); Wed, 31 Jul 2019 05:43:24 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 41104307D85E; Wed, 31 Jul 2019 09:43:24 +0000 (UTC) Received: from thuth.remote.csb (dhcp-200-228.str.redhat.com [10.33.200.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 927105D9E1; Wed, 31 Jul 2019 09:43:17 +0000 (UTC) Subject: Re: [PATCH 1/2] KVM: selftests: Implement ucall() for s390x To: Andrew Jones Cc: kvm@vger.kernel.org, Christian Borntraeger , Janosch Frank , linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, David Hildenbrand , Cornelia Huck , Paolo Bonzini , =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , Shuah Khan , Peter Xu References: <20190730100112.18205-1-thuth@redhat.com> <20190730100112.18205-2-thuth@redhat.com> <20190730104807.7uzuvd52foybakgu@kamzik.brq.redhat.com> From: Thomas Huth Openpgp: preference=signencrypt Autocrypt: addr=thuth@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <20190730104807.7uzuvd52foybakgu@kamzik.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Wed, 31 Jul 2019 09:43:24 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 30/07/2019 12.48, Andrew Jones wrote: > On Tue, Jul 30, 2019 at 12:01:11PM +0200, Thomas Huth wrote: >> On s390x, we can neither exit via PIO nor MMIO, but have to use >> an instruction like DIAGNOSE. While we're at it, rename UCALL_PIO >> to UCALL_DEFAULT, since PIO only works on x86 anyway, and this >> way we can re-use the "default" type for the DIAGNOSE exit on s390x. >> >> Now that ucall() is implemented, we can use it in the sync_reg_test >> on s390x, too. >> >> Signed-off-by: Thomas Huth >> --- >> .../testing/selftests/kvm/include/kvm_util.h | 2 +- >> tools/testing/selftests/kvm/lib/ucall.c | 34 +++++++++++++++---- >> .../selftests/kvm/s390x/sync_regs_test.c | 6 ++-- >> 3 files changed, 32 insertions(+), 10 deletions(-) >> >> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h >> index e0e66b115ef2..c37aea2e33e5 100644 >> --- a/tools/testing/selftests/kvm/include/kvm_util.h >> +++ b/tools/testing/selftests/kvm/include/kvm_util.h >> @@ -167,7 +167,7 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd); >> >> /* ucall implementation types */ >> typedef enum { >> - UCALL_PIO, >> + UCALL_DEFAULT, > > I'd rather we keep explicit types defined; keep PIO and add DIAG. Then > we can have > > /* Set default ucall types */ > #if defined(__x86_64__) > ucall_type = UCALL_PIO; > #elif defined(__aarch64__) > ucall_type = UCALL_MMIO; > ucall_requires_init = true; > #elif defined(__s390x__) > ucall_type = UCALL_DIAG; > #endif > > And add an assert in get_ucall() > > assert(!ucall_requires_init || ucall_initialized); I'm not sure whether I really like that. It's yet another additional #ifdef block, and yet another variable ... What do you think about removing the enum completely and simply code it directly, without the ucall_type indirection, i.e.: void ucall(uint64_t cmd, int nargs, ...) { struct ucall uc = { .cmd = cmd, }; va_list va; int i; nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS; va_start(va, nargs); for (i = 0; i < nargs; ++i) uc.args[i] = va_arg(va, uint64_t); va_end(va); #if defined(__x86_64__) /* Exit via PIO */ asm volatile("in %[port], %%al" : : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax"); #elif defined(__aarch64__) *ucall_exit_mmio_addr = (vm_vaddr_t)&uc; #elif defined(__s390x__) /* Exit via DIAGNOSE 0x501 (normally used for breakpoints) */ asm volatile ("diag 0,%0,0x501" : : "a"(&uc) : "memory"); #endif } I think that's way less confusing than having to understand the meaning of ucall_type etc. before...? Thomas