From nobody Mon Apr 6 17:41:41 2026 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=1664873085; cv=none; d=zohomail.com; s=zohoarc; b=m9ZAm/L3IxcZtkS/CU1LCVX+YX66GGvVe+kyhd0+hrbZG7gpsln5XuIHRjDs0r3pXZdoEetMOtrppvpCYG7BxS54wSkDdIDG/VRruVsp5SjrLej2m8bFvUYDGw1dPXVjf8ZUmBfUhso1ohtrOJLFCzYzUqDavvVf+7e+xLcS0w8= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1664873085; 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=rg7G2sE/xwQjZFXkh5AfLZ6BOzaSFVCwXC3avs7dOhM=; b=LgeX4yy+v5vKFT2NM4r/n0S1VhxMm8PUtpqGjPxtHtsFZ35kMi9ns8Z3aMoeAPDthmgBJSTO/4ocLawTBYIjPQfe9vX0HExOgAvp4bVtbkefgFE27qtHZ1Qd/z5xeSqBB2MVKByV5aGnVXbKUz89vFM2rWztV5a4pI/9KBoRvoY= 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 166487308531834.87437012154453; Tue, 4 Oct 2022 01:44:45 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.415262.659805 (Exim 4.92) (envelope-from ) id 1ofdXQ-00042B-AW; Tue, 04 Oct 2022 08:44:28 +0000 Received: by outflank-mailman (output) from mailman id 415262.659805; Tue, 04 Oct 2022 08:44:28 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ofdXQ-000424-7M; Tue, 04 Oct 2022 08:44:28 +0000 Received: by outflank-mailman (input) for mailman id 415262; Tue, 04 Oct 2022 08:44:26 +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 1ofdXO-0003R3-EF for xen-devel@lists.xenproject.org; Tue, 04 Oct 2022 08:44:26 +0000 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by se1-gles-sth1.inumbo.com (Halon) with ESMTPS id c0296207-43c0-11ed-964a-05401a9f4f97; Tue, 04 Oct 2022 10:44:25 +0200 (CEST) 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-out2.suse.de (Postfix) with ESMTPS id 5E8B41F8FC; Tue, 4 Oct 2022 08:44:25 +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 17BC0139D2; Tue, 4 Oct 2022 08:44:25 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 1/l0BGnyO2O4VwAAMHmgww (envelope-from ); Tue, 04 Oct 2022 08:44:25 +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: c0296207-43c0-11ed-964a-05401a9f4f97 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1664873065; 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=rg7G2sE/xwQjZFXkh5AfLZ6BOzaSFVCwXC3avs7dOhM=; b=A+NxQexafoTYnVQ/mf4TVXN0GkLKIg2mP5sKyx1Gz2V3ktHdatz1HlJqgWcQIRhl5hOeoT 3Q0+qKFhx2Ufd9teMM1JVfivPQD8aszyNe/LecnT3KZRw2nHdoey3kERS7LrsUGl99ZLcS S5gceBOro6LRxBH1JdWTsKpWGfKCeuU= 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 v2 2/3] xen/pv: refactor msr access functions to support safe and unsafe accesses Date: Tue, 4 Oct 2022 10:43:34 +0200 Message-Id: <20221004084335.2838-3-jgross@suse.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20221004084335.2838-1-jgross@suse.com> References: <20221004084335.2838-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1664873085828100003 Content-Type: text/plain; charset="utf-8" Refactor and rename xen_read_msr_safe() and xen_write_msr_safe() to support both cases of MSR accesses, safe ones and potentially GP-fault generating ones. This will prepare to no longer swallow GPs silently in xen_read_msr() and xen_write_msr(). Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich --- V2: - init val in xen_do_read_msr() to 0 (Jan Beulich) --- arch/x86/xen/enlighten_pv.c | 75 +++++++++++++++++++++++++++---------- 1 file changed, 56 insertions(+), 19 deletions(-) diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 9b1a58dda935..d5b0844a1b7c 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -917,14 +917,18 @@ static void xen_write_cr4(unsigned long cr4) native_write_cr4(cr4); } =20 -static u64 xen_read_msr_safe(unsigned int msr, int *err) +static u64 xen_do_read_msr(unsigned int msr, int *err) { - u64 val; + u64 val =3D 0; /* Avoid uninitialized value for safe variant. */ =20 if (pmu_msr_read(msr, &val, err)) return val; =20 - val =3D native_read_msr_safe(msr, err); + if (err) + val =3D native_read_msr_safe(msr, err); + else + val =3D native_read_msr(msr); + switch (msr) { case MSR_IA32_APICBASE: val &=3D ~X2APIC_ENABLE; @@ -933,23 +937,39 @@ static u64 xen_read_msr_safe(unsigned int msr, int *e= rr) return val; } =20 -static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned hig= h) +static void set_seg(unsigned int which, unsigned int low, unsigned int hig= h, + int *err) { - int ret; - unsigned int which; - u64 base; + u64 base =3D ((u64)high << 32) | low; + + if (HYPERVISOR_set_segment_base(which, base) =3D=3D 0) + return; =20 - ret =3D 0; + if (err) + *err =3D -EIO; + else + WARN(1, "Xen set_segment_base(%u, %llx) failed\n", which, base); +} =20 +/* + * Support write_msr_safe() and write_msr() semantics. + * With err =3D=3D NULL write_msr() semantics are selected. + * Supplying an err pointer requires err to be pre-initialized with 0. + */ +static void xen_do_write_msr(unsigned int msr, unsigned int low, + unsigned int high, int *err) +{ switch (msr) { - case MSR_FS_BASE: which =3D SEGBASE_FS; goto set; - case MSR_KERNEL_GS_BASE: which =3D SEGBASE_GS_USER; goto set; - case MSR_GS_BASE: which =3D SEGBASE_GS_KERNEL; goto set; - - set: - base =3D ((u64)high << 32) | low; - if (HYPERVISOR_set_segment_base(which, base) !=3D 0) - ret =3D -EIO; + case MSR_FS_BASE: + set_seg(SEGBASE_FS, low, high, err); + break; + + case MSR_KERNEL_GS_BASE: + set_seg(SEGBASE_GS_USER, low, high, err); + break; + + case MSR_GS_BASE: + set_seg(SEGBASE_GS_KERNEL, low, high, err); break; =20 case MSR_STAR: @@ -965,11 +985,28 @@ static int xen_write_msr_safe(unsigned int msr, unsig= ned low, unsigned high) break; =20 default: - if (!pmu_msr_write(msr, low, high, &ret)) - ret =3D native_write_msr_safe(msr, low, high); + if (!pmu_msr_write(msr, low, high, err)) { + if (err) + *err =3D native_write_msr_safe(msr, low, high); + else + native_write_msr(msr, low, high); + } } +} + +static u64 xen_read_msr_safe(unsigned int msr, int *err) +{ + return xen_do_read_msr(msr, err); +} + +static int xen_write_msr_safe(unsigned int msr, unsigned int low, + unsigned int high) +{ + int err =3D 0; + + xen_do_write_msr(msr, low, high, &err); =20 - return ret; + return err; } =20 static u64 xen_read_msr(unsigned int msr) --=20 2.35.3