From patchwork Thu Mar 26 15:24:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Elisei X-Patchwork-Id: 11460509 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 57FBE1667 for ; Thu, 26 Mar 2020 15:25:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42B822076A for ; Thu, 26 Mar 2020 15:25:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728465AbgCZPZa (ORCPT ); Thu, 26 Mar 2020 11:25:30 -0400 Received: from foss.arm.com ([217.140.110.172]:33946 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728496AbgCZPZa (ORCPT ); Thu, 26 Mar 2020 11:25:30 -0400 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 BB0CD1045; Thu, 26 Mar 2020 08:25:29 -0700 (PDT) Received: from e123195-lin.cambridge.arm.com (e123195-lin.cambridge.arm.com [10.1.196.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id D295C3F71E; Thu, 26 Mar 2020 08:25:28 -0700 (PDT) From: Alexandru Elisei To: kvm@vger.kernel.org Cc: will@kernel.org, julien.thierry.kdev@gmail.com, andre.przywara@arm.com, sami.mujawar@arm.com, lorenzo.pieralisi@arm.com Subject: [PATCH v3 kvmtool 31/32] vfio: Trap MMIO access to BAR addresses which aren't page aligned Date: Thu, 26 Mar 2020 15:24:37 +0000 Message-Id: <20200326152438.6218-32-alexandru.elisei@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200326152438.6218-1-alexandru.elisei@arm.com> References: <20200326152438.6218-1-alexandru.elisei@arm.com> MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org KVM_SET_USER_MEMORY_REGION will fail if the guest physical address is not aligned to the page size. However, it is legal for a guest to program an address which isn't aligned to the page size. Trap and emulate MMIO accesses to the region when that happens. Without this patch, when assigning a Seagate Barracude hard drive to a VM I was seeing these errors: [ 0.286029] pci 0000:00:00.0: BAR 0: assigned [mem 0x41004600-0x4100467f] Error: 0000:01:00.0: failed to register region with KVM Error: [1095:3132] Error activating emulation for BAR 0 [..] [ 10.561794] irq 13: nobody cared (try booting with the "irqpoll" option) [ 10.563122] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.4.0-seattle-00009-g909b20467ed1 #133 [ 10.563124] Hardware name: linux,dummy-virt (DT) [ 10.563126] Call trace: [ 10.563134] dump_backtrace+0x0/0x140 [ 10.563137] show_stack+0x14/0x20 [ 10.563141] dump_stack+0xbc/0x100 [ 10.563146] __report_bad_irq+0x48/0xd4 [ 10.563148] note_interrupt+0x288/0x378 [ 10.563151] handle_irq_event_percpu+0x80/0x88 [ 10.563153] handle_irq_event+0x44/0xc8 [ 10.563155] handle_fasteoi_irq+0xb4/0x160 [ 10.563157] generic_handle_irq+0x24/0x38 [ 10.563159] __handle_domain_irq+0x60/0xb8 [ 10.563162] gic_handle_irq+0x50/0xa0 [ 10.563164] el1_irq+0xb8/0x180 [ 10.563166] arch_cpu_idle+0x10/0x18 [ 10.563170] do_idle+0x204/0x290 [ 10.563172] cpu_startup_entry+0x20/0x40 [ 10.563175] rest_init+0xd4/0xe0 [ 10.563180] arch_call_rest_init+0xc/0x14 [ 10.563182] start_kernel+0x420/0x44c [ 10.563183] handlers: [ 10.563650] [<000000001e474803>] sil24_interrupt [ 10.564559] Disabling IRQ #13 [..] [ 11.832916] ata1: spurious interrupt (slot_stat 0x0 active_tag -84148995 sactive 0x0) [ 12.045444] ata_ratelimit: 1 callbacks suppressed With this patch, I don't see the errors and the device works as expected. Reviewed-by: Andre Przywara Signed-off-by: Alexandru Elisei --- vfio/core.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/vfio/core.c b/vfio/core.c index bad3c7c8cd26..0b45e78b40b4 100644 --- a/vfio/core.c +++ b/vfio/core.c @@ -226,6 +226,15 @@ int vfio_map_region(struct kvm *kvm, struct vfio_device *vdev, if (!(region->info.flags & VFIO_REGION_INFO_FLAG_MMAP)) return vfio_setup_trap_region(kvm, vdev, region); + /* + * KVM_SET_USER_MEMORY_REGION will fail because the guest physical + * address isn't page aligned, let's emulate the region ourselves. + */ + if (region->guest_phys_addr & (PAGE_SIZE - 1)) + return kvm__register_mmio(kvm, region->guest_phys_addr, + region->info.size, false, + vfio_mmio_access, region); + if (region->info.flags & VFIO_REGION_INFO_FLAG_READ) prot |= PROT_READ; if (region->info.flags & VFIO_REGION_INFO_FLAG_WRITE)