From nobody Mon Feb 9 18:18:55 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=1664201966; cv=none; d=zohomail.com; s=zohoarc; b=UbSKtq53jzbUHJ/df6Je+NHXK+XmzAW4V49O/Zbxh6+DseRfhIEbXaDUhMeg4T5wQ9uxtQqqgpXRzjXlEdiYEczr2sajv08tK4/VjG+OMfo14IbVNc5wzfdUSfZO6oskrmkA2xO0+1foWHQhVIuA310bnTLZVgEcbKEmdAeCJMA= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1664201966; 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=Q2WIgyc8oeY+zl5KU1xJK3+56bjqBOzQeuZ/l6BD6ls=; b=ExfKqolUfi3OlsN1kr5jjp61o106oV8WIuLrfvUh+1Vn/8azmx+rNSNjPdSm0DaqTvBeQB58eWNvzqCJMSkKZnRN3oEP7bgVwNn6vAHMJjAZ48F/czlZ0z3pTj4w9oiH492sgx79dRKOyiSue6Imx1IbPYd6MapY03TOm7qMWKo= 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 1664201966876687.9147965396554; Mon, 26 Sep 2022 07:19:26 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.411854.654963 (Exim 4.92) (envelope-from ) id 1ocows-0005We-Pq; Mon, 26 Sep 2022 14:19:06 +0000 Received: by outflank-mailman (output) from mailman id 411854.654963; Mon, 26 Sep 2022 14:19:06 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ocows-0005WT-MY; Mon, 26 Sep 2022 14:19:06 +0000 Received: by outflank-mailman (input) for mailman id 411854; Mon, 26 Sep 2022 14:19:06 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ocows-0005DG-1C for xen-devel@lists.xenproject.org; Mon, 26 Sep 2022 14:19:06 +0000 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 2d256888-3da6-11ed-9374-c1cf23e5d27e; Mon, 26 Sep 2022 16:19:05 +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-out1.suse.de (Postfix) with ESMTPS id D1F7321AA9; Mon, 26 Sep 2022 14:19:04 +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 8BECF139BD; Mon, 26 Sep 2022 14:19:04 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id NfvmINi0MWOZBgAAMHmgww (envelope-from ); Mon, 26 Sep 2022 14:19:04 +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: 2d256888-3da6-11ed-9374-c1cf23e5d27e DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1664201944; 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=Q2WIgyc8oeY+zl5KU1xJK3+56bjqBOzQeuZ/l6BD6ls=; b=qY8RvPXiIpmNppBtHhVvR/lcYb5+KrHTOtwch6dvTPWN8X/VLj6Cw/YIS2IJ+d1ByhjLv6 J/em/IezcFP+FLxo0JYsBoM3a1BAcvDVDlg27PUngju+UZucwdMDwAW0kSQx57aTdV54Yt FjdIzmNYyktbjc3IVUg5Yiuu9DvK60Y= From: Juergen Gross To: xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Boris Ostrovsky , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" Subject: [PATCH 2/3] xen/pv: refactor msr access functions to support safe and unsafe accesses Date: Mon, 26 Sep 2022 16:18:48 +0200 Message-Id: <20220926141849.21805-3-jgross@suse.com> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220926141849.21805-1-jgross@suse.com> References: <20220926141849.21805-1-jgross@suse.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1664201969315100001 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 --- arch/x86/xen/enlighten_pv.c | 73 ++++++++++++++++++++++++++++--------- 1 file changed, 55 insertions(+), 18 deletions(-) diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 0ed2e487a693..4e68e047df94 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -916,14 +916,18 @@ 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; =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; @@ -932,23 +936,39 @@ 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: @@ -964,11 +984,28 @@ 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