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=-10.0 required=3.0 tests=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 603EFC0650F for ; Mon, 5 Aug 2019 12:16:26 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 1F70A2086D for ; Mon, 5 Aug 2019 12:16:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F70A2086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id BADCB4A53B; Mon, 5 Aug 2019 08:16:25 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id fVuWqetT9zJn; Mon, 5 Aug 2019 08:16:24 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 3E5B04A53D; Mon, 5 Aug 2019 08:16:23 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 32A7A4A4E6 for ; Mon, 5 Aug 2019 08:16:22 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ZZPTppG7Vn9x for ; Mon, 5 Aug 2019 08:16:21 -0400 (EDT) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 41D0A4A540 for ; Mon, 5 Aug 2019 08:16:20 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id D94B21597; Mon, 5 Aug 2019 05:16:19 -0700 (PDT) Received: from filthy-habits.cambridge.arm.com (filthy-habits.cambridge.arm.com [10.1.197.61]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BC6473F77D; Mon, 5 Aug 2019 05:16:18 -0700 (PDT) From: Marc Zyngier To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: [PATCH 2/2] KVM: arm: Don't write junk to CP15 registers on reset Date: Mon, 5 Aug 2019 13:15:55 +0100 Message-Id: <20190805121555.130897-3-maz@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190805121555.130897-1-maz@kernel.org> References: <20190805121555.130897-1-maz@kernel.org> MIME-Version: 1.0 X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu 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 --- 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 d2806bcff8bb..07745ee022a1 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 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm