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[2620:137:e000::1:20]) by mx.google.com with ESMTP id q2-20020a50aa82000000b004449134b500si1835427edc.311.2022.08.16.06.17.04; Tue, 16 Aug 2022 06:17:34 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@alien8.de header.s=dkim header.b=JXU2pzIc; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=alien8.de Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235397AbiHPNDb (ORCPT + 99 others); Tue, 16 Aug 2022 09:03:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46832 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235026AbiHPNDH (ORCPT ); Tue, 16 Aug 2022 09:03:07 -0400 Received: from mail.skyhub.de (mail.skyhub.de [5.9.137.197]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DAA5CB5A4C; Tue, 16 Aug 2022 06:01:39 -0700 (PDT) Received: from zn.tnic (p200300ea971b9855329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:971b:9855:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 1C7131EC01D4; Tue, 16 Aug 2022 15:01:34 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1660654894; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QDaKfCiFgyxx3ZrcVJwM3i4NjJJIQ4/lD6ZRQjvQcgk=; b=JXU2pzIcu9Fk1uibAAqMT0OC4FflwKs80pbYWItFXioWQdaFZNreBGN1NXA/rznno491xy ffGHUinTK6RVZeMNT7TE1w9yuag6UNy+jhGNDiuc/qvf/gbTCbZ3JtaAVCchngo24l0onV lGQV6b7t4AiDjv5br40xFa1R+hRKztE= Date: Tue, 16 Aug 2022 15:01:33 +0200 From: Borislav Petkov To: Andrew Cooper Cc: Peter Zijlstra , Greg Kroah-Hartman , "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" , Daniel Sneddon , Pawan Gupta , Thomas Gleixner , "x86@kernel.org" , Josh Poimboeuf Subject: Re: [PATCH] x86/nospec: Unwreck the RSB stuffing Message-ID: References: <20220809175513.345597655@linuxfoundation.org> <20220809175513.979067723@linuxfoundation.org> <82d09944-9118-e727-705d-da513eca0bf1@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <82d09944-9118-e727-705d-da513eca0bf1@citrix.com> X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 16, 2022 at 12:52:58PM +0000, Andrew Cooper wrote: > One minor point.  Stuff 32 slots. > > There are Intel parts out in the world with RSBs larger than 32 entries, > and this loop does not fill the entire RSB on those. > > This is why the 32-entry stuffing loop is explicitly not supported on > eIBRS hardware as a general mechanism. I'm guessing there will be an Intel patch forthcoming, making that RSB_CLEAR_LOOPS more dynamic, based on the current model. :-) -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette