Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Fri, 2019-01-11 at 09:50 +0100, Peter Lieven wrote: > > Am 11.01.2019 um 08:14 schrieb Vadim Rozenfeld > >: > > > > > On Thu, 2019-01-10 at 14:57 +0100, Peter Lieven wrote: > > > > Am 18.12.18 um 15:45 schrieb Peter Lieven: > > > > > Am 18.12.18 um 14:15 schrieb Vadim Rozenfeld: > > > > >

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

> Am 11.01.2019 um 08:14 schrieb Vadim Rozenfeld : > >> On Thu, 2019-01-10 at 14:57 +0100, Peter Lieven wrote: >>> Am 18.12.18 um 15:45 schrieb Peter Lieven: Am 18.12.18 um 14:15 schrieb Vadim Rozenfeld: Peter, I must be missing something here, but what exactly the problem

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Thu, 2019-01-10 at 14:57 +0100, Peter Lieven wrote: > Am 18.12.18 um 15:45 schrieb Peter Lieven: > > Am 18.12.18 um 14:15 schrieb Vadim Rozenfeld: > > > Peter, I must be missing something here, but what exactly the > > > problem > > > is? > > > > The issue is that I see concurrent read

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Am 18.12.18 um 15:45 schrieb Peter Lieven: Am 18.12.18 um 14:15 schrieb Vadim Rozenfeld: Peter, I must be missing something here, but what exactly the problem is? The issue is that I see concurrent read requests coming in from Windows Guest with vioscsi as driver that have the same buffer

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Mon, 2018-12-17 at 18:07 -0500, Michael S. Tsirkin wrote: > On Mon, Dec 17, 2018 at 04:19:53PM +0100, Peter Lieven wrote: > > Am 17.12.18 um 15:48 schrieb Stefan Hajnoczi: > > > On Sun, Dec 16, 2018 at 06:53:44PM +0100, Peter Lieven wrote: > > > > It turned out that for writes a bounce buffer

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Am 18.12.18 um 14:15 schrieb Vadim Rozenfeld: > Peter, I must be missing something here, but what exactly the problem > is? The issue is that I see concurrent read requests coming in from Windows Guest with vioscsi as driver that have the same buffer address from guest memory space. I noticed

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Am 18.12.18 um 10:34 schrieb Stefan Hajnoczi: > On Mon, Dec 17, 2018 at 04:19:53PM +0100, Peter Lieven wrote: >> Actually I don't know for sure that the address comes from the guest. In >> theory it could be that >> the request from the guest was less than 4096 byte and Qemu just assigned a >>

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Mon, Dec 17, 2018 at 04:19:53PM +0100, Peter Lieven wrote: > Actually I don't know for sure that the address comes from the guest. In > theory it could be that > the request from the guest was less than 4096 byte and Qemu just assigned a > bounce buffer > to read the whole block and copied

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Mon, Dec 17, 2018 at 04:19:53PM +0100, Peter Lieven wrote: > Am 17.12.18 um 15:48 schrieb Stefan Hajnoczi: > > On Sun, Dec 16, 2018 at 06:53:44PM +0100, Peter Lieven wrote: > > > It turned out that for writes a bounce buffer is indeed always necessary. > > > But what I found out is that > > >

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Am 17.12.18 um 15:48 schrieb Stefan Hajnoczi: On Sun, Dec 16, 2018 at 06:53:44PM +0100, Peter Lieven wrote: It turned out that for writes a bounce buffer is indeed always necessary. But what I found out is that it seems that even for reads it happens that the OS (Windows in this case) issues

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

On Sun, Dec 16, 2018 at 06:53:44PM +0100, Peter Lieven wrote: > It turned out that for writes a bounce buffer is indeed always necessary. But > what I found out is that > it seems that even for reads it happens that the OS (Windows in this case) > issues 2 read requests with > the same buffer in

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Von: Paolo Bonzini > > Yes, it's ugly but it's legal.  It probably doesn't happen on real hardware > > that computes the checksum after or during DMA and has some kind of buffer > > inside the board.  But on virt there is only one copy until we reach the > > actual physical hardware.

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

> > Yes, it's ugly but it's legal. It probably doesn't happen on real hardware > > that computes the checksum after or during DMA and has some kind of buffer > > inside the board. But on virt there is only one copy until we reach the > > actual physical hardware. > > okay, so it's no bug. and

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

> Am 07.06.2017 um 01:17 schrieb Paolo Bonzini : > > > > - Original Message - >> From: "Peter Lieven" >> To: "qemu block" >> Cc: "Paolo Bonzini" , stefa...@redhat.com, >> kw...@redhat.com, "Max Reitz"

Re: [Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

- Original Message - > From: "Peter Lieven" > To: "qemu block" > Cc: "Paolo Bonzini" , stefa...@redhat.com, > kw...@redhat.com, "Max Reitz" , > "Michael S. Tsirkin" > Sent: Tuesday, June 6,

[Qemu-block] Virtio-BLK/SCSI write requests and data payload checksums

Hi, ich have spend several hours debugging a strange checksum error issue and finally found the cause, but I am totally unsure if whats happening is correct or not. Imagine a Protocol like iSCSI which has a Data Digest and which receives its data via zero copy straight from the guest kernel