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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 545C3CA9EC7 for ; Tue, 29 Oct 2019 07:20:36 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 28AE721479 for ; Tue, 29 Oct 2019 07:20:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 28AE721479 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 B93094A4C0; Tue, 29 Oct 2019 03:20:35 -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 OTqvvVIgfLFd; Tue, 29 Oct 2019 03:20:34 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A90D84A958; Tue, 29 Oct 2019 03:20:34 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 27ED14A534 for ; Tue, 29 Oct 2019 03:20:32 -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 yhMrCwpGak4Y for ; Tue, 29 Oct 2019 03:20:31 -0400 (EDT) Received: from huawei.com (szxga06-in.huawei.com [45.249.212.32]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id C83D34A49C for ; Tue, 29 Oct 2019 03:20:30 -0400 (EDT) Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 453D89AEB92ADC6E058B; Tue, 29 Oct 2019 15:20:27 +0800 (CST) Received: from DESKTOP-8RFUVS3.china.huawei.com (10.173.222.27) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.439.0; Tue, 29 Oct 2019 15:20:17 +0800 From: Zenghui Yu To: , , , , Subject: [PATCH 3/3] KVM: arm/arm64: vgic: Don't rely on the wrong pending table Date: Tue, 29 Oct 2019 15:19:19 +0800 Message-ID: <20191029071919.177-4-yuzenghui@huawei.com> X-Mailer: git-send-email 2.23.0.windows.1 In-Reply-To: <20191029071919.177-1-yuzenghui@huawei.com> References: <20191029071919.177-1-yuzenghui@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.173.222.27] X-CFilter-Loop: Reflected Cc: kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, 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-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 It's possible that two LPIs locate in the same "byte_offset" but target two different vcpus, where their pending status are indicated by two different pending tables. In such a scenario, using last_byte_offset optimization will lead KVM relying on the wrong pending table entry. Let us use last_ptr instead, which can be treated as a byte index into a pending table and also, can be vcpu specific. Signed-off-by: Zenghui Yu --- If this patch has done the right thing, we can even add the: Fixes: 280771252c1b ("KVM: arm64: vgic-v3: KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES") But to be honest, I'm not clear about what has this patch actually fixed. Pending tables should contain all zeros before we flush vgic_irq's pending status into guest's RAM (thinking that guest should never write anything into it). So the pending table entry we've read from the guest memory seems always be zero. And we will always do the right thing even if we rely on the wrong pending table entry. I think I must have some misunderstanding here... Please fix me. virt/kvm/arm/vgic/vgic-v3.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c index 5ef93e5041e1..7cd2e2f81513 100644 --- a/virt/kvm/arm/vgic/vgic-v3.c +++ b/virt/kvm/arm/vgic/vgic-v3.c @@ -363,8 +363,8 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq) int vgic_v3_save_pending_tables(struct kvm *kvm) { struct vgic_dist *dist = &kvm->arch.vgic; - int last_byte_offset = -1; struct vgic_irq *irq; + gpa_t last_ptr = -1; int ret; u8 val; @@ -384,11 +384,11 @@ int vgic_v3_save_pending_tables(struct kvm *kvm) bit_nr = irq->intid % BITS_PER_BYTE; ptr = pendbase + byte_offset; - if (byte_offset != last_byte_offset) { + if (ptr != last_ptr) { ret = kvm_read_guest_lock(kvm, ptr, &val, 1); if (ret) return ret; - last_byte_offset = byte_offset; + last_ptr = ptr; } stored = val & (1U << bit_nr); -- 2.19.1 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm