similar to: [PATCH 1/1] virtio_ring: fix return code on DMA mapping fails

On Fri, 26 Apr 2019 20:32:39 +0200 Halil Pasic <pasic at linux.ibm.com> wrote: > On s390, protected virtualization guests have to use bounced I/O > buffers. That requires some plumbing. > > Let us make sure, any device that uses DMA API with direct ops > correctly is spared from the problems, that a hypervisor attempting > I/O to a non-shared page would bring. > >

On Fri, 26 Apr 2019 20:32:39 +0200 Halil Pasic <pasic at linux.ibm.com> wrote: > On s390, protected virtualization guests have to use bounced I/O > buffers. That requires some plumbing. > > Let us make sure, any device that uses DMA API with direct ops > correctly is spared from the problems, that a hypervisor attempting > I/O to a non-shared page would bring. > >

On Sat, Nov 23, 2019 at 09:39:08AM -0600, Tom Lendacky wrote: > Ideally, having a pool of shared pages for DMA, outside of standard > SWIOTLB, might be a good thing. On x86, SWIOTLB really seems geared > towards devices that don't support 64-bit DMA. If a device supports 64-bit > DMA then it can use shared pages that reside anywhere to perform the DMA > and bounce buffering. I

On 11/22/19 7:08 AM, Halil Pasic wrote: > Thanks Michael! > > Actually I also hoped to start a discussion on virtio with encrypted > memory. > > I assume the AMD folks have the most experience with this, and I very > much like to understand how do they master the challenges we are all > facing. > > My understanding of IO in the context of AMD SEV is that the user

Hi Halil, When swiotlb full is hit for virtio_blk, there is below warning for once (the warning is not by this patch set). Is this expected or just false positive? [ 54.767257] virtio-pci 0000:00:04.0: swiotlb buffer is full (sz: 16 bytes), total 32768 (slots), used 258 (slots) [ 54.767260] virtio-pci 0000:00:04.0: overflow 0x0000000075770110+16 of DMA mask ffffffffffffffff bus limit 0 [

Two patches are handling new edge cases introduced by doing DMA mappings (which can fail) in virtio core. I stumbled upon this while stress testing I/O for Protected Virtual Machines. I deliberately chose a tiny swiotlb size and have generated load with fio. With more than one virtio-blk disk in use I experienced hangs. The goal of this series is to fix those hangs. Halil Pasic (2):

Two patches are handling new edge cases introduced by doing DMA mappings (which can fail) in virtio core. I stumbled upon this while stress testing I/O for Protected Virtual Machines. I deliberately chose a tiny swiotlb size and have generated load with fio. With more than one virtio-blk disk in use I experienced hangs. The goal of this series is to fix those hangs. Halil Pasic (2):

On Thu, Feb 13, 2020 at 8:38 PM Halil Pasic <pasic at linux.ibm.com> wrote: > > Since nobody else is going to restart our hw_queue for us, the > blk_mq_start_stopped_hw_queues() is in virtblk_done() is not sufficient > necessarily sufficient to ensure that the queue will get started again. > In case of global resource outage (-ENOMEM because mapping failure, > because of

On Thu, Feb 13, 2020 at 8:38 PM Halil Pasic <pasic at linux.ibm.com> wrote: > > Since nobody else is going to restart our hw_queue for us, the > blk_mq_start_stopped_hw_queues() is in virtblk_done() is not sufficient > necessarily sufficient to ensure that the queue will get started again. > In case of global resource outage (-ENOMEM because mapping failure, > because of

On Tue, Feb 18, 2020 at 8:35 PM Halil Pasic <pasic at linux.ibm.com> wrote: > > On Tue, 18 Feb 2020 10:21:18 +0800 > Ming Lei <tom.leiming at gmail.com> wrote: > > > On Thu, Feb 13, 2020 at 8:38 PM Halil Pasic <pasic at linux.ibm.com> wrote: > > > > > > Since nobody else is going to restart our hw_queue for us, the > > >

On Mon, 27 May 2019 14:30:14 +0200 Halil Pasic <pasic at linux.ibm.com> wrote: > On Mon, 27 May 2019 12:38:02 +0200 > Cornelia Huck <cohuck at redhat.com> wrote: > > > On Thu, 23 May 2019 18:22:04 +0200 > > Michael Mueller <mimu at linux.ibm.com> wrote: > > > > > From: Halil Pasic <pasic at linux.ibm.com> > > > > >

On Mon, 27 May 2019 14:30:14 +0200 Halil Pasic <pasic at linux.ibm.com> wrote: > On Mon, 27 May 2019 12:38:02 +0200 > Cornelia Huck <cohuck at redhat.com> wrote: > > > On Thu, 23 May 2019 18:22:04 +0200 > > Michael Mueller <mimu at linux.ibm.com> wrote: > > > > > From: Halil Pasic <pasic at linux.ibm.com> > > > > >

On Tue, Mar 03, 2020 at 03:12:52PM +0100, Halil Pasic wrote: > On Thu, 13 Feb 2020 13:37:26 +0100 > Halil Pasic <pasic at linux.ibm.com> wrote: > > > Two patches are handling new edge cases introduced by doing DMA mappings > > (which can fail) in virtio core. > > > > I stumbled upon this while stress testing I/O for Protected Virtual > > Machines. I

On Thu, 23 May 2019 18:22:04 +0200 Michael Mueller <mimu at linux.ibm.com> wrote: > From: Halil Pasic <pasic at linux.ibm.com> > > As virtio-ccw devices are channel devices, we need to use the dma area > for any communication with the hypervisor. > > It handles neither QDIO in the common code, nor any device type specific > stuff (like channel programs

On Thu, 23 May 2019 18:22:04 +0200 Michael Mueller <mimu at linux.ibm.com> wrote: > From: Halil Pasic <pasic at linux.ibm.com> > > As virtio-ccw devices are channel devices, we need to use the dma area > for any communication with the hypervisor. > > It handles neither QDIO in the common code, nor any device type specific > stuff (like channel programs

Commit 780bc7903a32 ("virtio_ring: Support DMA APIs") makes virtqueue_add() return -EIO when we fail to map our I/O buffers. This is a very realistic scenario for guests with encrypted memory, as swiotlb may run out of space, depending on it's size and the I/O load. The virtio-blk driver interprets -EIO form virtqueue_add() as an IO error, despite the fact that swiotlb full is in

On Thu, 13 Jun 2019 11:11:13 +0200 Michael Mueller <mimu at linux.ibm.com> wrote: > Halil, > > I just ran my toleration tests successfully on current HW for > this series. > > Michael Thanks Michael! May I add a Tested-by: Michael Mueller <mimu at linux.ibm.com> for each patch? > > On 12.06.19 13:12, Halil Pasic wrote: > > Enhanced virtualization

Enhanced virtualization protection technology may require the use of bounce buffers for I/O. While support for this was built into the virtio core, virtio-ccw wasn't changed accordingly. Some background on technology (not part of this series) and the terminology used. * Protected Virtualization (PV): Protected Virtualization guarantees, that non-shared memory of a guest that operates in PV

Enhanced virtualization protection technology may require the use of bounce buffers for I/O. While support for this was built into the virtio core, virtio-ccw wasn't changed accordingly. Some background on technology (not part of this series) and the terminology used. * Protected Virtualization (PV): Protected Virtualization guarantees, that non-shared memory of a guest that operates in PV

On Fri, 26 Apr 2019 20:32:41 +0200 Halil Pasic <pasic at linux.ibm.com> wrote: > As virtio-ccw devices are channel devices, we need to use the dma area > for any communication with the hypervisor. > > This patch addresses the most basic stuff (mostly what is required for > virtio-ccw), and does take care of QDIO or any devices. "does not take care of QDIO",