From patchwork Tue May 10 12:37:17 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Graf X-Patchwork-Id: 1629143 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=amazon.com header.i=@amazon.com header.a=rsa-sha256 header.s=amazon201209 header.b=Krqz6XaU; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org (client-ip=2404:9400:2:0:216:3eff:fee1:b9f1; helo=lists.ozlabs.org; envelope-from=linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org; receiver=) Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2404:9400:2:0:216:3eff:fee1:b9f1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by bilbo.ozlabs.org (Postfix) with ESMTPS id 4KyHfP3pc3z9sGF for ; Tue, 10 May 2022 22:39:09 +1000 (AEST) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4KyHfP1H31z3c8W for ; Tue, 10 May 2022 22:39:09 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=amazon.com header.i=@amazon.com header.a=rsa-sha256 header.s=amazon201209 header.b=Krqz6XaU; dkim-atps=neutral X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=amazon.de (client-ip=207.171.188.200; helo=smtp-fw-9103.amazon.com; envelope-from=prvs=122be4948=graf@amazon.de; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=amazon.com header.i=@amazon.com header.a=rsa-sha256 header.s=amazon201209 header.b=Krqz6XaU; dkim-atps=neutral Received: from smtp-fw-9103.amazon.com (smtp-fw-9103.amazon.com [207.171.188.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4KyHf73SSzz2y7K for ; Tue, 10 May 2022 22:38:55 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1652186335; x=1683722335; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=bE2GOy6zlpqOoRX6zYpnJAL0E/MfIkSIFEmV3eldp8g=; b=Krqz6XaUUHZThkl/yRqUry7d1WENP04gEDbD5avnWSKaU2LaWxKvxjWZ S9odBy0+xePutiJ/wb4VJeLpxQD6c1QForL/d7G7B+HqkI+1FveFvZlN+ 2MiWBXn1GNP3UZEaMDC9F7TGstpXWWIlPZbb1CMU/UGxTMZCkyGA0I3AR U=; X-IronPort-AV: E=Sophos;i="5.91,214,1647302400"; d="scan'208";a="1014326555" Received: from pdx4-co-svc-p1-lb2-vlan2.amazon.com (HELO email-inbound-relay-pdx-2a-e6c05252.us-west-2.amazon.com) ([10.25.36.210]) by smtp-border-fw-9103.sea19.amazon.com with ESMTP; 10 May 2022 12:37:27 +0000 Received: from EX13MTAUWC001.ant.amazon.com (pdx1-ws-svc-p6-lb9-vlan2.pdx.amazon.com [10.236.137.194]) by email-inbound-relay-pdx-2a-e6c05252.us-west-2.amazon.com (Postfix) with ESMTPS id 0A4E441CEE; Tue, 10 May 2022 12:37:27 +0000 (UTC) Received: from EX13D20UWC001.ant.amazon.com (10.43.162.244) by EX13MTAUWC001.ant.amazon.com (10.43.162.135) with Microsoft SMTP Server (TLS) id 15.0.1497.32; Tue, 10 May 2022 12:37:26 +0000 Received: from u79c5a0a55de558.ant.amazon.com (10.43.162.96) by EX13D20UWC001.ant.amazon.com (10.43.162.244) with Microsoft SMTP Server (TLS) id 15.0.1497.32; Tue, 10 May 2022 12:37:24 +0000 From: Alexander Graf To: Subject: [PATCH v3] KVM: PPC: Book3S PR: Enable MSR_DR for switch_mmu_context() Date: Tue, 10 May 2022 14:37:17 +0200 Message-ID: <20220510123717.24508-1-graf@amazon.com> X-Mailer: git-send-email 2.28.0.394.ge197136389 MIME-Version: 1.0 X-Originating-IP: [10.43.162.96] X-ClientProxiedBy: EX13D03UWC002.ant.amazon.com (10.43.162.160) To EX13D20UWC001.ant.amazon.com (10.43.162.244) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Matt Evans , linux-kernel@vger.kernel.org, Paul Mackerras , stable@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Commit 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C") moved the switch_mmu_context() to C. While in principle a good idea, it meant that the function now uses the stack. The stack is not accessible from real mode though. So to keep calling the function, let's turn on MSR_DR while we call it. That way, all pointer references to the stack are handled virtually. In addition, make sure to save/restore r12 on the stack, as it may get clobbered by the C function. Reported-by: Matt Evans Fixes: 863771a28e27 ("powerpc/32s: Convert switch_mmu_context() to C") Signed-off-by: Alexander Graf Cc: stable@vger.kernel.org # v5.14+ --- v1 -> v2: - Save and restore R12, so that we don't touch volatile registers while calling into C. v2 -> v3: - Save and restore R12 on the stack. SPRGs may be clobbered by page faults. --- arch/powerpc/kvm/book3s_32_sr.S | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/arch/powerpc/kvm/book3s_32_sr.S b/arch/powerpc/kvm/book3s_32_sr.S index e3ab9df6cf19..6cfcd20d4668 100644 --- a/arch/powerpc/kvm/book3s_32_sr.S +++ b/arch/powerpc/kvm/book3s_32_sr.S @@ -122,11 +122,27 @@ /* 0x0 - 0xb */ - /* 'current->mm' needs to be in r4 */ - tophys(r4, r2) - lwz r4, MM(r4) - tophys(r4, r4) - /* This only clobbers r0, r3, r4 and r5 */ + /* switch_mmu_context() needs paging, let's enable it */ + mfmsr r9 + ori r11, r9, MSR_DR + mtmsr r11 + sync + + /* switch_mmu_context() clobbers r12, rescue it */ + SAVE_GPR(12, r1) + + /* Calling switch_mmu_context(, current->mm, ); */ + lwz r4, MM(r2) bl switch_mmu_context + /* restore r12 */ + REST_GPR(12, r1) + + /* Disable paging again */ + mfmsr r9 + li r6, MSR_DR + andc r9, r9, r6 + mtmsr r9 + sync + .endm