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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 AA3E3C7618F for ; Thu, 18 Jul 2019 02:02:02 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 354872173B for ; Thu, 18 Jul 2019 02:02:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 354872173B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com 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 9100D4A56F; Wed, 17 Jul 2019 22:02:01 -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 43H0T8dp+md2; Wed, 17 Jul 2019 22:02:00 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 6AB734A555; Wed, 17 Jul 2019 22:02:00 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id BE30C4A555 for ; Wed, 17 Jul 2019 22:01:58 -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 jfXmLK0OSaoS for ; Wed, 17 Jul 2019 22:01:56 -0400 (EDT) Received: from huawei.com (szxga04-in.huawei.com [45.249.212.190]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id E63C24A52A for ; Wed, 17 Jul 2019 22:01:55 -0400 (EDT) Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id B923175E6D083B2475B5; Thu, 18 Jul 2019 10:01:52 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.439.0; Thu, 18 Jul 2019 10:01:46 +0800 Subject: Re: [PATCH] KVM: arm/arm64: Assign pmc->idx before kvm_pmu_stop_counter() To: Marc Zyngier , Julien Thierry , , References: <1563366019-31200-1-git-send-email-yuzenghui@huawei.com> <01fa98c1-8274-445c-5e04-219372920ba2@arm.com> <26b64d48-5ff9-7d62-bc44-601fdcc43223@kernel.org> From: Zenghui Yu Message-ID: Date: Thu, 18 Jul 2019 09:59:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:64.0) Gecko/20100101 Thunderbird/64.0 MIME-Version: 1.0 In-Reply-To: <26b64d48-5ff9-7d62-bc44-601fdcc43223@kernel.org> Content-Language: en-US X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Cc: marc.zyngier@arm.com, linux-kernel@vger.kernel.org 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Hi Julien, Marc, On 2019/7/17 23:00, Marc Zyngier wrote: > On 17/07/2019 14:44, Julien Thierry wrote: >> Hi Zenghui, >> >> On 17/07/2019 13:20, Zenghui Yu wrote: >>> We use "pmc->idx" and the "chained" bitmap to determine if the pmc is >>> chained, in kvm_pmu_pmc_is_chained(). But idx might be uninitialized >>> (and random) when we doing this decision, through a KVM_ARM_VCPU_INIT >>> ioctl -> kvm_pmu_vcpu_reset(). And the test_bit() against this random >>> idx will potentially hit a KASAN BUG [1]. >>> >>> Fix it by moving the assignment of idx before kvm_pmu_stop_counter(). >>> >>> [1] https://www.spinics.net/lists/kvm-arm/msg36700.html >>> >>> Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters") >>> Suggested-by: Andrew Murray >>> Cc: Marc Zyngier >>> Signed-off-by: Zenghui Yu > --- >>> virt/kvm/arm/pmu.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c >>> index 3dd8238..521bfdd 100644 >>> --- a/virt/kvm/arm/pmu.c >>> +++ b/virt/kvm/arm/pmu.c >>> @@ -225,8 +225,8 @@ void kvm_pmu_vcpu_reset(struct kvm_vcpu *vcpu) >>> struct kvm_pmu *pmu = &vcpu->arch.pmu; >>> >>> for (i = 0; i < ARMV8_PMU_MAX_COUNTERS; i++) { >>> - kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]); >>> pmu->pmc[i].idx = i; >> >> Yes, this is kind of a static property that should really be part of a >> "kvm_pmu_vcpu_init()" or "kvm_pmu_vcpu_create()" and is not expected to >> be modified across resets... >> >> There is no such function at the time and I'm unsure whether this >> warrants creating that separate function (I would still suggest creating >> it to make things clearer). > > Yup, that's pretty bad, now that you mention it. I'd be all for the > introduction of kvm_pmu_vcpu_init(), given that we already have > kvm_pmu_vcpu_destroy(). > >> >>> + kvm_pmu_stop_counter(vcpu, &pmu->pmc[i]); >> >> Whatever other opinions are on splitting pmu_vcpu_init/reset, that >> change makes sense and fixes the issue: >> >> Acked-by: Julien Thierry >> >>> } >>> >>> bitmap_zero(vcpu->arch.pmu.chained, ARMV8_PMU_MAX_COUNTER_PAIRS); >>> >> >> Cheers, >> > > Zenghui, could you please update your patch to take the above into account? Sure. I will send a v2 with the new subject (may be "KVM: arm/arm64: Introduce kvm_pmu_vcpu_init() to ..."). Thanks for your suggestions! zenghui _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm