From mboxrd@z Thu Jan 1 00:00:00 1970 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 43CF5C6FA82 for ; Mon, 26 Sep 2022 15:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236748AbiIZPdc (ORCPT ); Mon, 26 Sep 2022 11:33:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52152 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236293AbiIZPcz (ORCPT ); Mon, 26 Sep 2022 11:32:55 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AE25501BC for ; Mon, 26 Sep 2022 07:19:06 -0700 (PDT) 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) 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= 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 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: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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); } -static u64 xen_read_msr_safe(unsigned int msr, int *err) +static u64 xen_do_read_msr(unsigned int msr, int *err) { u64 val; if (pmu_msr_read(msr, &val, err)) return val; - val = native_read_msr_safe(msr, err); + if (err) + val = native_read_msr_safe(msr, err); + else + val = native_read_msr(msr); + switch (msr) { case MSR_IA32_APICBASE: val &= ~X2APIC_ENABLE; @@ -932,23 +936,39 @@ static u64 xen_read_msr_safe(unsigned int msr, int *err) return val; } -static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) +static void set_seg(unsigned int which, unsigned int low, unsigned int high, + int *err) { - int ret; - unsigned int which; - u64 base; + u64 base = ((u64)high << 32) | low; + + if (HYPERVISOR_set_segment_base(which, base) == 0) + return; - ret = 0; + if (err) + *err = -EIO; + else + WARN(1, "Xen set_segment_base(%u, %llx) failed\n", which, base); +} +/* + * Support write_msr_safe() and write_msr() semantics. + * With err == 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 = SEGBASE_FS; goto set; - case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set; - case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set; - - set: - base = ((u64)high << 32) | low; - if (HYPERVISOR_set_segment_base(which, base) != 0) - ret = -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; case MSR_STAR: @@ -964,11 +984,28 @@ static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high) break; default: - if (!pmu_msr_write(msr, low, high, &ret)) - ret = native_write_msr_safe(msr, low, high); + if (!pmu_msr_write(msr, low, high, err)) { + if (err) + *err = 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 = 0; + + xen_do_write_msr(msr, low, high, &err); - return ret; + return err; } static u64 xen_read_msr(unsigned int msr) -- 2.35.3