Re: [PATCH v2 3/8] s390/cio: add basic protected virtualization support

Michael Mueller
2019-05-27T12:15:27Z

On 27.05.19 12:38, Cornelia Huck wrote:
> On Thu, 23 May 2019 18:22:04 +0200
> Michael Mueller <mimu@linux.ibm.com> wrote:
>
>> From: Halil Pasic <pasic@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 constructed by the DASD driver).
>>
>> An interesting side effect is that virtio structures are now going to
>> get allocated in 31 bit addressable storage.
>>
>> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
>
> [Side note: you really should add your s-o-b if you send someone else's
> patches... if Halil ends up committing them, it's fine, though.]

My real problem here is that Halil is writing comments and patches after
I have prepared all my changes. ;) And now this contnues...

Michael

>
>> ---
>> arch/s390/include/asm/ccwdev.h | 4 +++
>> drivers/s390/cio/ccwreq.c | 9 +++---
>> drivers/s390/cio/device.c | 64 +++++++++++++++++++++++++++++++++-------
>> drivers/s390/cio/device_fsm.c | 53 ++++++++++++++++++++-------------
>> drivers/s390/cio/device_id.c | 20 +++++++------
>> drivers/s390/cio/device_ops.c | 21 +++++++++++--
>> drivers/s390/cio/device_pgid.c | 22 +++++++-------
>> drivers/s390/cio/device_status.c | 24 +++++++--------
>> drivers/s390/cio/io_sch.h | 20 +++++++++----
>> drivers/s390/virtio/virtio_ccw.c | 10 -------
>> 10 files changed, 164 insertions(+), 83 deletions(-)
>>
>
> (...)
>
>> @@ -1593,20 +1622,31 @@ struct ccw_device * __init ccw_device_create_console(struct ccw_driver *drv)
>> return ERR_CAST(sch);
>>
>> io_priv = kzalloc(sizeof(*io_priv), GFP_KERNEL | GFP_DMA);
>> - if (!io_priv) {
>> - put_device(&sch->dev);
>> - return ERR_PTR(-ENOMEM);
>> - }
>> + if (!io_priv)
>> + goto err_priv;
>> + io_priv->dma_area = dma_alloc_coherent(&sch->dev,
>> + sizeof(*io_priv->dma_area),
>> + &io_priv->dma_area_dma, GFP_KERNEL);
>
> Even though we'll only end up here for 3215 or 3270 consoles, this sent
> me looking.
>
> This code is invoked via console_init(). A few lines down in
> start_kernel(), we have
>
> /*
> * This needs to be called before any devices perform DMA
> * operations that might use the SWIOTLB bounce buffers. It will
> * mark the bounce buffers as decrypted so that their usage will
> * not cause "plain-text" data to be decrypted when accessed.
> */
> mem_encrypt_init();
>
> So, I'm wondering if creating the console device interacts in any way
> with the memory encryption interface?
>
> [Does basic recognition work if you start a protected virt guest with a
> 3270 console? I realize that the console is unlikely to work, but that
> should at least exercise this code path.]
>
>> + if (!io_priv->dma_area)
>> + goto err_dma_area;
>> set_io_private(sch, io_priv);
>> cdev = io_subchannel_create_ccwdev(sch);
>> if (IS_ERR(cdev)) {
>> put_device(&sch->dev);
>> + dma_free_coherent(&sch->dev, sizeof(*io_priv->dma_area),
>> + io_priv->dma_area, io_priv->dma_area_dma);
>> kfree(io_priv);
>> return cdev;
>> }
>> cdev->drv = drv;
>> ccw_device_set_int_class(cdev);
>> return cdev;
>> +
>> +err_dma_area:
>> + kfree(io_priv);
>> +err_priv:
>> + put_device(&sch->dev);
>> + return ERR_PTR(-ENOMEM);
>> }
>>
>> void __init ccw_device_destroy_console(struct ccw_device *cdev)
>