Igor Skalkin
2022-Oct-11 12:23 UTC
[PATCH] virtio_bt: Fix alignment in configuration struct
Hi Luiz, Current version of this patch is wrong [q]changing uapi like this can't be done, will break userspace[/q], next version is in process, will be sent in few days. Best regards, Igor On 10/7/22 21:33, Luiz Augusto von Dentz wrote:> Hi Michael, > > On Fri, Oct 7, 2022 at 6:03 AM Michael S. Tsirkin <mst at redhat.com> wrote: >> >> On Mon, Aug 08, 2022 at 02:04:43PM +0200, Igor Skalkin wrote: >>> On 8/8/22 01:00, Michael S. Tsirkin wrote: >>> >>> On Mon, Aug 08, 2022 at 12:11:52AM +0200, Igor Skalkin wrote: >>> >>> According to specification [1], "For the device-specific configuration >>> space, the driver MUST use 8 bit wide accesses for 8 bit wide fields, >>> 16 bit wide and aligned accesses for 16 bit wide fields and 32 bit wide >>> and aligned accesses for 32 and 64 bit wide fields.". >>> >>> Current version of the configuration structure: >>> >>> struct virtio_bt_config { >>> __u8 type; >>> __u16 vendor; >>> __u16 msft_opcode; >>> } __attribute__((packed)); >>> >>> has both 16bit fields non-aligned. >>> >>> This commit fixes it. >>> >>> [1] https://ddec1-0-en-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=https%3a%2f%2fdocs.oasis%2dopen.org%2fvirtio%2fvirtio%2fv1.1%2fvirtio%2dv1.1.pdf&umid=b1110db2-819d-4f27-b35e-18ac23ce0ab4&auth=53c7c7de28b92dfd96e93d9dd61a23e634d2fbec-2c53002097633a932e7d67b899e6bf6999cdc899 >>> >>> Signed-off-by: Igor Skalkin <Igor.Skalkin at opensynergy.com> >>> >>> This is all true enough, but the problem is >>> 1. changing uapi like this can't be done, will break userspace >>> 2. the driver has more issues and no one seems to want to >>> maintain it. >>> I posted a patch "Bluetooth: virtio_bt: mark broken" and intend >>> to merge it for this release. >>> >>> This is very sad. We already use this driver in our projects. >> >> Ping. If we still have no maintainer I'm marking it broken, users >> should at least be warned. > > Please resend. > >> >>> Our virtio bluetooth device has two backends - HCI_USER socket backend for one >>> platform and uart backend for the other, and works well (after applying your >>> "[PATCH] Bluetooth: virtio_bt: fix device remove") patch, so this "device >>> removal" problem can probably be considered solved . >>> We could help with the rest of the problems you listed that can be solved >>> (specification, QEMU support). >>> And the only problem that is difficult to solve (because of the need to change >>> UAPI header files) is just this one with unaligned configuration fields. >>> At the moment, it does not reproduce, because without VIRTIO_BT_F_VND_HCI >>> (Indicates vendor command support) feature negotiated, the driver does not >>> read the non-aligned configuration fields. >>> >>> So, what would you advise us to do? Continuing to use the "marked broken" >>> driver, start writing a specification for a new from scratch, better one? >>> Or is there any way to bring this one back to life? >>> >>> >>> >>> --- >>> include/uapi/linux/virtio_bt.h | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/include/uapi/linux/virtio_bt.h b/include/uapi/linux/virtio_bt.h >>> index a7bd48daa9a9..adc03709cc4f 100644 >>> --- a/include/uapi/linux/virtio_bt.h >>> +++ b/include/uapi/linux/virtio_bt.h >>> @@ -23,9 +23,9 @@ enum virtio_bt_config_vendor { >>> }; >>> >>> struct virtio_bt_config { >>> - __u8 type; >>> __u16 vendor; >>> __u16 msft_opcode; >>> + __u8 type; >>> } __attribute__((packed)); >>> >>> #endif /* _UAPI_LINUX_VIRTIO_BT_H */ >>> -- >>> 2.34.1 >>> >>> -- >>> >>> Best regards, >>> >>> Igor Skalkin >>> Software Engineer >>> >>> OpenSynergy GmbH >>> Rotherstr. 20, 10245 Berlin >>> >>> igor.skalkin at opensynergy.com >>> www.opensynergy.com >>> >>> registered: Amtsgericht Charlottenburg, HRB 108616B >>> General Management: Rolf Morich, Stefaan Sonck Thiebaut >>> >>> >>> Please mind our privacy notice pursuant to Art. 13 GDPR. // Unsere Hinweise zum >>> Datenschutz gem. Art. 13 DSGVO finden Sie hier. >> > >Please mind our privacy notice<https://www.opensynergy.com/datenschutzerklaerung/privacy-notice-for-business-partners-pursuant-to-article-13-of-the-general-data-protection-regulation-gdpr/> pursuant to Art. 13 GDPR. // Unsere Hinweise zum Datenschutz gem. Art. 13 DSGVO finden Sie hier.<https://www.opensynergy.com/de/datenschutzerklaerung/datenschutzhinweise-fuer-geschaeftspartner-gem-art-13-dsgvo/>