From patchwork Wed Feb 1 13:57:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Emanuele Giuseppe Esposito X-Patchwork-Id: 13124352 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 1334FC636D3 for ; Wed, 1 Feb 2023 13:58:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1pNDcv-0006lj-6O; Wed, 01 Feb 2023 08:58:17 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNDct-0006l7-9m for qemu-devel@nongnu.org; Wed, 01 Feb 2023 08:58:15 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1pNDcr-00033r-RA for qemu-devel@nongnu.org; Wed, 01 Feb 2023 08:58:15 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675259893; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6E43QDqsPyPDXX60KATrLVlrphoW+MpFw34uTLFnIbA=; b=HwU/qCEqsWv8OFY/RCRfcyy09t+OfQ/Puu5p+NCaIEprf9tPoczE45wcdM8TLa0JhZmAl2 v9cEGXBo881iZU0IuXy1yK7WCFCa0Y5LDGqs5Ox3MVdygxgyHMYcuLw9cybZVGnql+67rx nym2jmLSSyywjpwhXlVEdN3rz4kGSPM= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-464-ufRD_46yOUerd24msxYMvA-1; Wed, 01 Feb 2023 08:58:02 -0500 X-MC-Unique: ufRD_46yOUerd24msxYMvA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 09D5F3C218A0; Wed, 1 Feb 2023 13:58:02 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id C6AE040E4314; Wed, 1 Feb 2023 13:58:01 +0000 (UTC) From: Emanuele Giuseppe Esposito To: qemu-devel@nongnu.org Cc: Paolo Bonzini , Richard Henderson , Maxim Levitsky , Yang Zhong , Vitaly Kuznetsov , Jing Liu , Emanuele Giuseppe Esposito Subject: [PATCH 2/2] target/i386: add support for FB_CLEAR feature Date: Wed, 1 Feb 2023 08:57:59 -0500 Message-Id: <20230201135759.555607-3-eesposit@redhat.com> In-Reply-To: <20230201135759.555607-1-eesposit@redhat.com> References: <20230201135759.555607-1-eesposit@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.2 Received-SPF: pass client-ip=170.10.133.124; envelope-from=eesposit@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org As reported by the Intel's doc: "FB_CLEAR: The processor will overwrite fill buffer values as part of MD_CLEAR operations with the VERW instruction. On these processors, L1D_FLUSH does not overwrite fill buffer values." If this cpu feature is present in host, allow QEMU to choose whether to show it to the guest too. One disadvantage of not exposing it is that the guest will report a non existing vulnerability in /sys/devices/system/cpu/vulnerabilities/mmio_stale_data because the mitigation is present only when the cpu has (FLUSH_L1D and MD_CLEAR) or FB_CLEAR features enabled. Signed-off-by: Emanuele Giuseppe Esposito --- target/i386/cpu.h | 1 + target/i386/cpu.c | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/target/i386/cpu.h b/target/i386/cpu.h index 4948130900..68a6ded0d7 100644 --- a/target/i386/cpu.h +++ b/target/i386/cpu.h @@ -975,6 +975,7 @@ uint64_t x86_cpu_get_supported_feature_word(FeatureWord w, #define MSR_ARCH_CAP_PSCHANGE_MC_NO (1U << 6) #define MSR_ARCH_CAP_TSX_CTRL_MSR (1U << 7) #define MSR_ARCH_CAP_TAA_NO (1U << 8) +#define MSR_ARCH_CAP_FB_CLEAR (1U << 17) #define MSR_CORE_CAP_SPLIT_LOCK_DETECT (1U << 5) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 390120cad8..1405eb42d6 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -1010,7 +1010,7 @@ FeatureWordInfo feature_word_info[FEATURE_WORDS] = { "ssb-no", "mds-no", "pschange-mc-no", "tsx-ctrl", "taa-no", NULL, NULL, NULL, NULL, NULL, NULL, NULL, - NULL, NULL, NULL, NULL, + NULL, "fb-clear", NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,