From patchwork Fri Oct 11 11:07:08 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Christoffer Dall X-Patchwork-Id: 11185225 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id C8D5417D4 for ; Fri, 11 Oct 2019 11:08:15 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 91966206CD for ; Fri, 11 Oct 2019 11:08:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aGpZ6+7n" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 91966206CD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=Xo9mjPrkgIOlyQRywV5inWoO1gEpwdJ6v34N3yFv8dw=; b=aGpZ6+7n5KaSk7mBkRhJMFp+zX i1LitcKJLWtqQ0YofeP14VCw2ydUCixPKPVorXlqC+LSHqN52Svsr5dTmEMTPAjGPUSM4NsiAwPjY 6Q8gaRcKCXLa1lSFx6RncAQnai8G/jt9mKMAN7D9R/uVlBHJUT8BOlS4AFa5SdVTyfZYrGaWpQq3z 2vLF71ca3/RofoW7r3FI2tV+Fx6DZxIwEi9X1BwWkg19UNSCBikM+DLWZLpAS0hR/gKCnLvGuXXmU dUxRjnfSlvVNQsIgnxB2iU1c4gqG+s1VI45zy56rypjUyWrbD2D86v3ax9mkZiTtx+O75Za/H3wQi 4mNkjRYA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIsmI-00014A-Dg; Fri, 11 Oct 2019 11:08:10 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1iIslX-0000DO-Fe for linux-arm-kernel@lists.infradead.org; Fri, 11 Oct 2019 11:07:25 +0000 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 EC8231000; Fri, 11 Oct 2019 04:07:22 -0700 (PDT) Received: from localhost (e113682-lin.copenhagen.arm.com [10.32.145.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 7F2163F703; Fri, 11 Oct 2019 04:07:22 -0700 (PDT) From: Christoffer Dall To: kvmarm@lists.cs.columbia.edu Subject: [kvmtool v3 4/5] arm: Handle exits from undecoded load/store instructions Date: Fri, 11 Oct 2019 13:07:08 +0200 Message-Id: <20191011110709.2764-5-christoffer.dall@arm.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20191011110709.2764-1-christoffer.dall@arm.com> References: <20191011110709.2764-1-christoffer.dall@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191011_040723_664980_0C867D6D X-CRM114-Status: GOOD ( 17.61 ) X-Spam-Score: 0.0 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (0.0 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , =?utf-8?q?Daniel_P=2E_Berrang?= =?utf-8?q?=C3=A9?= , Suzuki K Poulose , Marc Zyngier , Christoffer Dall , James Morse , Julien Thierry , Stefan Hajnoczi , Heinrich Schuchardt , Alexander Graf , linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org KVM occasionally encounters guests that attempt to access memory outside the registered RAM memory slots using instructions that don't provide decoding information in the ESR_EL2 (the ISV bit is not set), and historically this has led to the kernel printing a confusing error message in dmesg and returning -ENOYSYS from KVM_RUN. KVM/Arm now has KVM_CAP_ARM_NISV_TO_USER, which can be enabled from userspace, and which allows us to handle this with a little bit more helpful information to the user. For example, we can at least tell the user if the guest just hit a hole in the guest's memory map, or if this appeared to be an attempt at doing MMIO. Signed-off-by: Christoffer Dall --- arm/kvm-cpu.c | 20 +++++++++++++++++++- arm/kvm.c | 8 ++++++++ include/kvm/kvm.h | 1 + kvm.c | 1 + mmio.c | 11 +++++++++++ 5 files changed, 40 insertions(+), 1 deletion(-) diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c index 7780251..25bd3ed 100644 --- a/arm/kvm-cpu.c +++ b/arm/kvm-cpu.c @@ -136,7 +136,25 @@ void kvm_cpu__delete(struct kvm_cpu *vcpu) bool kvm_cpu__handle_exit(struct kvm_cpu *vcpu) { - return false; + switch (vcpu->kvm_run->exit_reason) { + case KVM_EXIT_ARM_NISV: { + u64 phys_addr = vcpu->kvm_run->arm_nisv.fault_ipa; + + if (!arm_addr_in_ioport_region(phys_addr) && + !kvm__mmio_exists(vcpu, phys_addr)) + die("Guest accessed memory outside RAM and IO ranges"); + + /* + * We cannot fetch and decode instructions from a KVM guest, + * which used a load/store instruction that doesn't get + * decoded in the ESR towards an I/O device, so we have no + * choice but to exit to the user with an error. + */ + die("Guest accessed I/O device with unsupported load/store instruction"); + } + default: + return false; + } } void kvm_cpu__show_page_tables(struct kvm_cpu *vcpu) diff --git a/arm/kvm.c b/arm/kvm.c index 1f85fc6..2572ac2 100644 --- a/arm/kvm.c +++ b/arm/kvm.c @@ -59,6 +59,8 @@ void kvm__arch_set_cmdline(char *cmdline, bool video) void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size) { + struct kvm_enable_cap enable_cap = { .flags = 0 }; + /* * Allocate guest memory. We must align our buffer to 64K to * correlate with the maximum guest page size for virtio-mmio. @@ -83,6 +85,12 @@ void kvm__arch_init(struct kvm *kvm, const char *hugetlbfs_path, u64 ram_size) madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size, MADV_HUGEPAGE); + if (kvm__supports_extension(kvm, KVM_CAP_ARM_NISV_TO_USER)) { + enable_cap.cap = KVM_CAP_ARM_NISV_TO_USER; + if (ioctl(kvm->vm_fd, KVM_ENABLE_CAP, &enable_cap) < 0) + die("unable to enable NISV_TO_USER capability"); + } + /* Create the virtual GIC. */ if (gic__create(kvm, kvm->cfg.arch.irqchip)) die("Failed to create virtual GIC"); diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h index 7a73818..05d90ee 100644 --- a/include/kvm/kvm.h +++ b/include/kvm/kvm.h @@ -107,6 +107,7 @@ bool kvm__emulate_io(struct kvm_cpu *vcpu, u16 port, void *data, int direction, bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u8 is_write); int kvm__register_mem(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr, enum kvm_mem_type type); +bool kvm__mmio_exists(struct kvm_cpu *vcpu, u64 phys_addr); static inline int kvm__register_ram(struct kvm *kvm, u64 guest_phys, u64 size, void *userspace_addr) { diff --git a/kvm.c b/kvm.c index 57c4ff9..03ec43f 100644 --- a/kvm.c +++ b/kvm.c @@ -55,6 +55,7 @@ const char *kvm_exit_reasons[] = { #ifdef CONFIG_PPC64 DEFINE_KVM_EXIT_REASON(KVM_EXIT_PAPR_HCALL), #endif + DEFINE_KVM_EXIT_REASON(KVM_EXIT_ARM_NISV), }; static int pause_event; diff --git a/mmio.c b/mmio.c index 61e1d47..2ab7fa7 100644 --- a/mmio.c +++ b/mmio.c @@ -139,3 +139,14 @@ bool kvm__emulate_mmio(struct kvm_cpu *vcpu, u64 phys_addr, u8 *data, u32 len, u return true; } + +bool kvm__mmio_exists(struct kvm_cpu *vcpu, u64 phys_addr) +{ + struct mmio_mapping *mmio; + + br_read_lock(vcpu->kvm); + mmio = mmio_search(&mmio_tree, phys_addr, 1); + br_read_unlock(vcpu->kvm); + + return mmio != NULL; +}