From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1163175AbcG0WTB (ORCPT ); Wed, 27 Jul 2016 18:19:01 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59256 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162535AbcG0WSu (ORCPT ); Wed, 27 Jul 2016 18:18:50 -0400 Date: Thu, 28 Jul 2016 01:18:42 +0300 From: "Michael S. Tsirkin" To: Namhyung Kim Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, Tony Luck , Radim =?utf-8?B?S3LEjW3DocWZ?= , Kees Cook , Anton Vorontsov , Will Deacon , LKML , Steven Rostedt , Minchan Kim , Anthony Liguori , Colin Cross , Paolo Bonzini , Ingo Molnar Subject: Re: [RFC/PATCHSET 0/7] virtio: Implement virtio pstore device (v2) Message-ID: <20160728011602-mutt-send-email-mst@kernel.org> References: <1469632111-23260-1-git-send-email-namhyung@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1469632111-23260-1-git-send-email-namhyung@kernel.org> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Wed, 27 Jul 2016 22:18:50 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 28, 2016 at 12:08:24AM +0900, Namhyung Kim wrote: > Hello, > > This is v2 of the virtio-pstore work. In this patchset I addressed > most of feedbacks from previous version. Limiting disk size is not > implemented yet. For some reason, only parts of the patchset were received. Pls post all patches to all lists. If you are changing the virtio interface with host, like a new device, they you must copy the virtio TC so make sure there are no objections from there. https://www.oasis-open.org/committees/tc_home.php?wg_abbrev=virtio#feedback > * changes in v2) > - update VIRTIO_ID_PSTORE to 22 (Cornelia, Stefan) > - make buffer size configurable (Cornelia) > - support PSTORE_TYPE_CONSOLE (Kees) > - use separate virtqueues for read and write > - support concurrent async write > - manage pstore (file) id in device side > - fix various mistakes in qemu device (Stefan) > > It started from the fact that dumping ftrace buffer at kernel > oops/panic takes too much time. Although there's a way to reduce the > size of the original data, sometimes I want to have the information as > many as possible. Maybe kexec/kdump can solve this problem but it > consumes some portion of guest memory so I'd like to avoid it. And I > know the qemu + crashtool can dump and analyze the whole guest memory > including the ftrace buffer without wasting guest memory, but it adds > one more layer and has some limitation as an out-of-tree tool like not > being in sync with the kernel changes. > > So I think it'd be great using the pstore interface to dump guest > kernel data on the host. One can read the data on the host directly > or on the guest (at the next boot) using pstore filesystem as usual. > While this patchset only implements dumping kernel log buffer, it can > be extended to have ftrace buffer and probably some more.. > > The patch 0001-0003 are preparation for pstore to support virtio > device which requires async write. The patch 0004 implements virtio > pstore driver. It has two virt queue for (sync) read and (async) > write, pstore buffer and io request and response structure. The > virtio_pstore_req struct is to give information about the current > pstore operation. The result will be written to the virtio_pstore_res > struct. For read operation it also uses virtio_pstore_fileinfo struct. > > The patch 0005 adds support for PSTORE_TYPE_CONSOLE which was > requested by Kees. The console data is appended to a single file for > now. > > The patch 0006 and 0007 implement virtio-pstore legacy PCI device on > qemu-kvm and kvmtool respectively. I referenced virtio-baloon and > virtio-rng implementations and I don't know whether kvmtool supports > modern virtio 1.0+ spec. Other transports might be supported later. > > For example, using virtio-pstore on qemu looks like below: > > $ qemu-system-x86_64 -enable-kvm -device virtio-pstore,directory=xxx > > When guest kernel gets panic the log messages will be saved under the > xxx directory. > > $ ls xxx > dmesg-1.enc.z dmesg-2.enc.z > > As you can see the pstore subsystem compresses the log data using zlib > (now supports lzo and lz4 too). The data can be extracted with the > following command: > > $ cat xxx/dmesg-1.enc.z | \ > > python -c 'import sys, zlib; print(zlib.decompress(sys.stdin.read()))' > Oops#1 Part1 > <5>[ 0.000000] Linux version 4.6.0kvm+ (namhyung@danjae) (gcc version 5.3.0 (GCC) ) #145 SMP Mon Jul 18 10:22:45 KST 2016 > <6>[ 0.000000] Command line: root=/dev/vda console=ttyS0 > <6>[ 0.000000] x86/fpu: Legacy x87 FPU detected. > <6>[ 0.000000] x86/fpu: Using 'eager' FPU context switches. > <6>[ 0.000000] e820: BIOS-provided physical RAM map: > <6>[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable > <6>[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved > <6>[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved > <6>[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x0000000007fddfff] usable > <6>[ 0.000000] BIOS-e820: [mem 0x0000000007fde000-0x0000000007ffffff] reserved > <6>[ 0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved > <6>[ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved > <6>[ 0.000000] NX (Execute Disable) protection: active > <6>[ 0.000000] SMBIOS 2.8 present. > <7>[ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 > ... > > To enable PSTORE_TYPE_CONSOLE, add 'console=true' to virtio-pstore > device option. Also 'bufsize' option can set different size for > pstore buffer (default is 16K). Maybe we can add a config option to > control the compression later. > > Currently the kvmtool doesn't support any options except the directory > the pstore saves the logs. > > > Namhyung Kim (7): > pstore: Split pstore fragile flags > pstore/ram: Set pstore flags dynamically > pstore: Manage buffer position for async write > virtio: Basic implementation of virtio pstore driver > virtio-pstore: Support PSTORE_TYPE_CONSOLE > qemu: Implement virtio-pstore device > kvmtool: Implement virtio-pstore device > > drivers/acpi/apei/erst.c | 2 +- > drivers/firmware/efi/efi-pstore.c | 4 +- > drivers/virtio/Kconfig | 10 + > drivers/virtio/Makefile | 1 + > drivers/virtio/virtio_pstore.c | 421 +++++++++++++++++++++ > fs/pstore/platform.c | 65 +++- > fs/pstore/ram.c | 8 + > include/linux/pstore.h | 9 +- > include/uapi/linux/Kbuild | 1 + > include/uapi/linux/virtio_ids.h | 1 + > include/uapi/linux/virtio_pstore.h | 78 +++- > 11 files changed, 580 insertions(+), 20 deletions(-) > create mode 100644 drivers/virtio/virtio_pstore.c > create mode 100644 include/uapi/linux/virtio_pstore.h > > > Cc: Paolo Bonzini > Cc: Radim Krčmář > Cc: "Michael S. Tsirkin" > Cc: Anthony Liguori > Cc: Anton Vorontsov > Cc: Colin Cross > Cc: Kees Cook > Cc: Tony Luck > Cc: Steven Rostedt > Cc: Ingo Molnar > Cc: Minchan Kim > Cc: Will Deacon > Cc: kvm@vger.kernel.org > Cc: qemu-devel@nongnu.org > Cc: virtualization@lists.linux-foundation.org > > Thanks, > Namhyung > > > -- > 2.8.0 > > _______________________________________________ > Virtualization mailing list > Virtualization@lists.linux-foundation.org > https://lists.linuxfoundation.org/mailman/listinfo/virtualization