From patchwork Fri Jan 25 22:06:05 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eduardo Habkost X-Patchwork-Id: 10782083 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 16EB3746 for ; Fri, 25 Jan 2019 22:06:14 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 04BF23083D for ; Fri, 25 Jan 2019 22:06:14 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id EC1EA308F7; Fri, 25 Jan 2019 22:06:13 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 8F1713083D for ; Fri, 25 Jan 2019 22:06:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729373AbfAYWGM (ORCPT ); Fri, 25 Jan 2019 17:06:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53354 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726218AbfAYWGM (ORCPT ); Fri, 25 Jan 2019 17:06:12 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 885438BA01; Fri, 25 Jan 2019 22:06:11 +0000 (UTC) Received: from localhost (ovpn-116-63.gru2.redhat.com [10.97.116.63]) by smtp.corp.redhat.com (Postfix) with ESMTP id AFB6060FDF; Fri, 25 Jan 2019 22:06:10 +0000 (UTC) From: Eduardo Habkost To: qemu-devel@nongnu.org Cc: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, Eduardo Habkost , Robert Hoo , Richard Henderson , Marcelo Tosatti , Tao Xu , Konrad Rzeszutek Wilk , Jim Mattson , KarimAllah Ahmed , David Woodhouse , Darren Kenny Subject: [PATCH 1/2] i386: kvm: Disable arch_capabilities if MSR can't be set Date: Fri, 25 Jan 2019 20:06:05 -0200 Message-Id: <20190125220606.4864-2-ehabkost@redhat.com> In-Reply-To: <20190125220606.4864-1-ehabkost@redhat.com> References: <20190125220606.4864-1-ehabkost@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Fri, 25 Jan 2019 22:06:11 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP KVM has two bugs in the handling of MSR_IA32_ARCH_CAPABILITIES: 1) Linux commit commit 1eaafe91a0df ("kvm: x86: IA32_ARCH_CAPABILITIES is always supported") makes GET_SUPPORTED_CPUID return arch_capabilities even if running on SVM. This makes "-cpu host,migratable=off" incorrectly expose arch_capabilities on CPUID on AMD hosts (where the MSR is not emulated by KVM). 2) KVM_GET_MSR_INDEX_LIST does not return MSR_IA32_ARCH_CAPABILITIES if the MSR is not supported by the host CPU. This makes QEMU not initialize the MSR properly at kvm_put_msrs() on those hosts. Work around both bugs on the QEMU side, by checking if the MSR was returned by KVM_GET_MSR_INDEX_LIST before returning the feature flag on kvm_arch_get_supported_cpuid(). This has the unfortunate side effect of making arch_capabilities unavailable on hosts without hardware support for the MSR until bug #2 is fixed on KVM, but I can't see another way to work around bug #1 without that side effect. Signed-off-by: Eduardo Habkost --- Cc: Konrad Rzeszutek Wilk Cc: Jim Mattson Cc: KarimAllah Ahmed Cc: David Woodhouse Cc: Darren Kenny --- target/i386/kvm.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/target/i386/kvm.c b/target/i386/kvm.c index 9af4542fb8..4fa3e3806a 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -389,6 +389,15 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, uint32_t function, if (host_tsx_blacklisted()) { ret &= ~(CPUID_7_0_EBX_RTM | CPUID_7_0_EBX_HLE); } + } else if (function == 7 && index == 0 && reg == R_EDX) { + /* + * Linux incorrectly v4.17-v4.20 return ARCH_CAPABILITIES on SVM. + * We can detect the bug by checking if MSR_IA32_ARCH_CAPABILITIES is + * returned by KVM_GET_MSR_INDEX_LIST. + */ + if (!has_msr_arch_capabs) { + ret &= ~CPUID_7_0_EDX_ARCH_CAPABILITIES; + } } else if (function == 0x80000001 && reg == R_ECX) { /* * It's safe to enable TOPOEXT even if it's not returned by From patchwork Fri Jan 25 22:06:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eduardo Habkost X-Patchwork-Id: 10782085 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B3D60746 for ; Fri, 25 Jan 2019 22:06:15 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A31633083D for ; Fri, 25 Jan 2019 22:06:15 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9680F308F7; Fri, 25 Jan 2019 22:06:15 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3615C3083D for ; Fri, 25 Jan 2019 22:06:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729388AbfAYWGO (ORCPT ); Fri, 25 Jan 2019 17:06:14 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60002 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728236AbfAYWGN (ORCPT ); Fri, 25 Jan 2019 17:06:13 -0500 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id B93B17BDA7; Fri, 25 Jan 2019 22:06:13 +0000 (UTC) Received: from localhost (ovpn-116-63.gru2.redhat.com [10.97.116.63]) by smtp.corp.redhat.com (Postfix) with ESMTP id 242FF608C3; Fri, 25 Jan 2019 22:06:12 +0000 (UTC) From: Eduardo Habkost To: qemu-devel@nongnu.org Cc: Paolo Bonzini , =?utf-8?b?UmFkaW0gS3LEjW3DocWZ?= , kvm@vger.kernel.org, Eduardo Habkost , Robert Hoo , Richard Henderson , Marcelo Tosatti , Tao Xu Subject: [PATCH 2/2] i386: Make arch_capabilities migratable Date: Fri, 25 Jan 2019 20:06:06 -0200 Message-Id: <20190125220606.4864-3-ehabkost@redhat.com> In-Reply-To: <20190125220606.4864-1-ehabkost@redhat.com> References: <20190125220606.4864-1-ehabkost@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 25 Jan 2019 22:06:13 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Now that kvm_arch_get_supported_cpuid() will only return arch_capabilities if QEMU is able to initialize the MSR properly, we know that the feature is safely migratable. Signed-off-by: Eduardo Habkost --- target/i386/cpu.c | 1 - 1 file changed, 1 deletion(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 2f5412592d..3ff91d794d 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1088,7 +1088,6 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { .reg = R_EDX, }, .tcg_features = TCG_7_0_EDX_FEATURES, - .unmigratable_flags = CPUID_7_0_EDX_ARCH_CAPABILITIES, }, [FEAT_8000_0007_EDX] = { .type = CPUID_FEATURE_WORD,