From nobody Wed Sep 10 02:29:25 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass(p=quarantine dis=none) header.from=suse.com ARC-Seal: i=1; a=rsa-sha256; t=1677144827; cv=none; d=zohomail.com; s=zohoarc; b=IZJjj0RiLJd/2MHY9ayNq1o6kaOmjvxSGlkK2n14ui63asHUrYxKdMXeD6EuMX7mXj9hA0nCNmIc1/dNnwV/t0nia2b0MJJdpgWJl0akv66sXRFrfxiOoSCLxLhl/GsQeKJ+bOVG0tcOoXquQXlntHyd01nS4aghse3ex6OeB5s= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1677144827; h=Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Help:List-Unsubscribe:MIME-Version:Message-ID:References:Sender:Subject:To; bh=bjil8ydj+MbGLi24YOvmKTY6GkdCwB8f6NUZv/v3iL0=; b=dZoe+DPHHnf0HbIg/luvDZ3s1FcrM3EJXpio3ILwlUDHS1EIcZGx4FOI3y/gcUC3FMXylFWxNh9/HFGJqReP9GcQn6sKfqSfNYxIXOavsKvmuAvsub7H1eDyPJFVxI9zsYDyAp2X+HhRQ0phSIZ0I3qQJV1+VQZiTLBOmRqdAOs= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=pass header.from= (p=quarantine dis=none) Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1677144827654724.4371218425067; Thu, 23 Feb 2023 01:33:47 -0800 (PST) Received: from list by lists.xenproject.org with outflank-mailman.499971.771271 (Exim 4.92) (envelope-from ) id 1pV7yX-0002Gt-M8; Thu, 23 Feb 2023 09:33:17 +0000 Received: by outflank-mailman (output) from mailman id 499971.771271; Thu, 23 Feb 2023 09:33:17 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pV7yX-0002Gm-JR; Thu, 23 Feb 2023 09:33:17 +0000 Received: by outflank-mailman (input) for mailman id 499971; Thu, 23 Feb 2023 09:33:16 +0000 Received: from se1-gles-sth1-in.inumbo.com ([159.253.27.254] helo=se1-gles-sth1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1pV7yW-0002Du-FD for xen-devel@lists.xenproject.org; Thu, 23 Feb 2023 09:33:16 +0000 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id 1939410a-b35d-11ed-88bb-e56d68cac8db; Thu, 23 Feb 2023 10:33:15 +0100 (CET) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id 596FD337F7; Thu, 23 Feb 2023 09:33:15 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 110F513928; Thu, 23 Feb 2023 09:33:15 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id a0MDAtsy92OmbAAAMHmgww (envelope-from ); Thu, 23 Feb 2023 09:33:15 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 1939410a-b35d-11ed-88bb-e56d68cac8db DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1677144795; h=from:from:reply-to: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=bjil8ydj+MbGLi24YOvmKTY6GkdCwB8f6NUZv/v3iL0=; b=f1lGkoc901x7lIfA6dv5NQpuQXuNT2Y9un8+vttO+jCblw1+Z+0VJz0GmtM8iUuNOWIJel zgALYUpQ3GLTcj425d8OzgfSLsqex9QOV+ZRjt7hqepTZeOZ4n5M0z2FX9oxt/xgInoJFz dMKS3jUEiMuk6ne8ZFQr4MNruZxSTtM= From: Juergen Gross To: linux-kernel@vger.kernel.org, x86@kernel.org Cc: Juergen Gross , Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , xen-devel@lists.xenproject.org Subject: [PATCH v3 05/12] x86/xen: set MTRR state when running as Xen PV initial domain Date: Thu, 23 Feb 2023 10:32:36 +0100 Message-Id: <20230223093243.1180-6-jgross@suse.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230223093243.1180-1-jgross@suse.com> References: <20230223093243.1180-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1677144829063100001 Content-Type: text/plain; charset="utf-8" When running as Xen PV initial domain (aka dom0), MTRRs are disabled by the hypervisor, but the system should nevertheless use correct cache memory types. This has always kind of worked, as disabled MTRRs resulted in disabled PAT, too, so that the kernel avoided code paths resulting in inconsistencies. This bypassed all of the sanity checks the kernel is doing with enabled MTRRs in order to avoid memory mappings with conflicting memory types. This has been changed recently, leading to PAT being accepted to be enabled, while MTRRs stayed disabled. The result is that mtrr_type_lookup() no longer is accepting all memory type requests, but started to return WB even if UC- was requested. This led to driver failures during initialization of some devices. In reality MTRRs are still in effect, but they are under complete control of the Xen hypervisor. It is possible, however, to retrieve the MTRR settings from the hypervisor. In order to fix those problems, overwrite the MTRR state via mtrr_overwrite_state() with the MTRR data from the hypervisor, if the system is running as a Xen dom0. Fixes: 72cbc8f04fe2 ("x86/PAT: Have pat_enabled() properly reflect state wh= en running on Xen") Signed-off-by: Juergen Gross --- V2: - new patch V3: - move the call of mtrr_overwrite_state() to xen_pv_init_platform() --- arch/x86/xen/enlighten_pv.c | 50 +++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index bb59cc6ddb2d..729fb447a5b6 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -68,6 +68,7 @@ #include #include #include +#include #include #include #include @@ -119,6 +120,52 @@ static int __init parse_xen_msr_safe(char *str) } early_param("xen_msr_safe", parse_xen_msr_safe); =20 +/* Get MTRR settings from Xen and put them into mtrr_state. */ +static void __init xen_set_mtrr_data(void) +{ +#ifdef CONFIG_MTRR + struct xen_platform_op op =3D { + .cmd =3D XENPF_read_memtype, + .interface_version =3D XENPF_INTERFACE_VERSION, + }; + unsigned int reg; + unsigned long mask; + uint32_t eax, width; + static struct mtrr_var_range var[MTRR_MAX_VAR_RANGES] __initdata; + + /* Get physical address width (only 64-bit cpus supported). */ + width =3D 36; + eax =3D cpuid_eax(0x80000000); + if ((eax >> 16) =3D=3D 0x8000 && eax >=3D 0x80000008) { + eax =3D cpuid_eax(0x80000008); + width =3D eax & 0xff; + } + + for (reg =3D 0; reg < MTRR_MAX_VAR_RANGES; reg++) { + op.u.read_memtype.reg =3D reg; + if (HYPERVISOR_platform_op(&op)) + break; + + /* + * Only called in dom0, which has all RAM PFNs mapped at + * RAM MFNs, and all PCI space etc. is identity mapped. + * This means we can treat MFN =3D=3D PFN regarding MTTR settings. + */ + var[reg].base_lo =3D op.u.read_memtype.type; + var[reg].base_lo |=3D op.u.read_memtype.mfn << PAGE_SHIFT; + var[reg].base_hi =3D op.u.read_memtype.mfn >> (32 - PAGE_SHIFT); + mask =3D ~((op.u.read_memtype.nr_mfns << PAGE_SHIFT) - 1); + mask &=3D (1UL << width) - 1; + if (mask) + mask |=3D 1 << 11; + var[reg].mask_lo =3D mask; + var[reg].mask_hi =3D mask >> 32; + } + + mtrr_overwrite_state(var, reg, MTRR_TYPE_UNCACHABLE); +#endif +} + static void __init xen_pv_init_platform(void) { /* PV guests can't operate virtio devices without grants. */ @@ -135,6 +182,9 @@ static void __init xen_pv_init_platform(void) =20 /* pvclock is in shared info area */ xen_init_time_ops(); + + if (xen_initial_domain()) + xen_set_mtrr_data(); } =20 static void __init xen_pv_guest_late_init(void) --=20 2.35.3