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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A471AC433FF for ; Wed, 14 Aug 2019 02:15:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C85220842 for ; Wed, 14 Aug 2019 02:15:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565748903; bh=OUie+gbJEPH0v/w4er6kUVBrDlqXOkXb9KmP3S61H+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kaTyceSP5V+ijJuaHnXvCjkwexbVHP+cwmgN30zLc+fQDfmNTVrmT2fuKzUCQiB9N h/xI+RpaBdeXuBPjG+6pNKytge3ImtJNzjM5NKHHdGk8MO+nicJ2VZlaAdVVlP3R2A qMFEZrCL7p9H9OlblT4PYxKWmAXbbAJl2jbIObTg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728803AbfHNCPC (ORCPT ); Tue, 13 Aug 2019 22:15:02 -0400 Received: from mail.kernel.org ([198.145.29.99]:46674 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728784AbfHNCOn (ORCPT ); Tue, 13 Aug 2019 22:14:43 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9B4012085A; Wed, 14 Aug 2019 02:14:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565748883; bh=OUie+gbJEPH0v/w4er6kUVBrDlqXOkXb9KmP3S61H+4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=xIug+PTmmJUZ90gU0zAz4aXv3ZF/jWfLZxSorBG/X0AfvBNBYOFjuC6xdVeRJj2qf F6adenMRElr+kMctQ93jicUTR6Kit9rr4cdlRc6blUbOc/m7zm6ouWjTcflqlYSDhR CGlndjJYJg43DDL5O6wzH2hyhQf9g7ZRC8zN2k9I= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marc Zyngier , Sasha Levin , kvmarm@lists.cs.columbia.edu Subject: [PATCH AUTOSEL 5.2 122/123] KVM: arm: Don't write junk to CP15 registers on reset Date: Tue, 13 Aug 2019 22:10:46 -0400 Message-Id: <20190814021047.14828-122-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190814021047.14828-1-sashal@kernel.org> References: <20190814021047.14828-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Marc Zyngier [ Upstream commit c69509c70aa45a8c4954c88c629a64acf4ee4a36 ] At the moment, the way we reset CP15 registers is mildly insane: We write junk to them, call the reset functions, and then check that we have something else in them. The "fun" thing is that this can happen while the guest is running (PSCI, for example). If anything in KVM has to evaluate the state of a CP15 register while junk is in there, bad thing may happen. Let's stop doing that. Instead, we track that we have called a reset function for that register, and assume that the reset function has done something. In the end, the very need of this reset check is pretty dubious, as it doesn't check everything (a lot of the CP15 reg leave outside of the cp15_regs[] array). It may well be axed in the near future. Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin --- arch/arm/kvm/coproc.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/arch/arm/kvm/coproc.c b/arch/arm/kvm/coproc.c index d2806bcff8bbb..07745ee022a12 100644 --- a/arch/arm/kvm/coproc.c +++ b/arch/arm/kvm/coproc.c @@ -651,13 +651,22 @@ int kvm_handle_cp14_64(struct kvm_vcpu *vcpu, struct kvm_run *run) } static void reset_coproc_regs(struct kvm_vcpu *vcpu, - const struct coproc_reg *table, size_t num) + const struct coproc_reg *table, size_t num, + unsigned long *bmap) { unsigned long i; for (i = 0; i < num; i++) - if (table[i].reset) + if (table[i].reset) { + int reg = table[i].reg; + table[i].reset(vcpu, &table[i]); + if (reg > 0 && reg < NR_CP15_REGS) { + set_bit(reg, bmap); + if (table[i].is_64bit) + set_bit(reg + 1, bmap); + } + } } static struct coproc_params decode_32bit_hsr(struct kvm_vcpu *vcpu) @@ -1432,17 +1441,15 @@ void kvm_reset_coprocs(struct kvm_vcpu *vcpu) { size_t num; const struct coproc_reg *table; - - /* Catch someone adding a register without putting in reset entry. */ - memset(vcpu->arch.ctxt.cp15, 0x42, sizeof(vcpu->arch.ctxt.cp15)); + DECLARE_BITMAP(bmap, NR_CP15_REGS) = { 0, }; /* Generic chip reset first (so target could override). */ - reset_coproc_regs(vcpu, cp15_regs, ARRAY_SIZE(cp15_regs)); + reset_coproc_regs(vcpu, cp15_regs, ARRAY_SIZE(cp15_regs), bmap); table = get_target_table(vcpu->arch.target, &num); - reset_coproc_regs(vcpu, table, num); + reset_coproc_regs(vcpu, table, num, bmap); for (num = 1; num < NR_CP15_REGS; num++) - WARN(vcpu_cp15(vcpu, num) == 0x42424242, + WARN(!test_bit(num, bmap), "Didn't reset vcpu_cp15(vcpu, %zi)", num); } -- 2.20.1