From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Reply-To: mimu@linux.ibm.com Subject: Re: [PATCH v2 3/8] s390/cio: add basic protected virtualization support References: <20190523162209.9543-1-mimu@linux.ibm.com> <20190523162209.9543-4-mimu@linux.ibm.com> <20190527123802.54cd3589.cohuck@redhat.com> <20190527143014.3b48a0d2.pasic@linux.ibm.com> <20190527153130.0f473ffd.cohuck@redhat.com> From: Michael Mueller Date: Wed, 29 May 2019 14:24:39 +0200 MIME-Version: 1.0 In-Reply-To: <20190527153130.0f473ffd.cohuck@redhat.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Message-Id: Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Cornelia Huck , Halil Pasic Cc: KVM Mailing List , Linux-S390 Mailing List , Sebastian Ott , Heiko Carstens , virtualization@lists.linux-foundation.org, "Michael S . Tsirkin" , Christoph Hellwig , Thomas Huth , Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman , Pierre Morel List-ID: On 27.05.19 15:31, Cornelia Huck wrote: > On Mon, 27 May 2019 14:30:14 +0200 > Halil Pasic wrote: > >> On Mon, 27 May 2019 12:38:02 +0200 >> Cornelia Huck wrote: >> >>> On Thu, 23 May 2019 18:22:04 +0200 >>> Michael Mueller wrote: >>> >>>> From: Halil Pasic >>>> >>>> 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 >>> >>> [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.] >>> >>>> --- >>>> 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? >> >> I do things a bit different than x86: the SWIOTLB stuff is set up in >> mem_init(). So I think we should be fine. If there is a down-side to >> calling swiotlb_update_mem_attributes() earlier, honestly I'm >> not sure. > > Neither am I; do any of the folks who looked at the swiotlb patch have > an idea? > >> >>> >>> [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.] >> >> I've already had some thoughts along these lines and slapped >> -device x-terminal3270,chardev=char_0,devno=fe.0.000a,id=terminal_0 \ >> on my qemu command line. The ccw device does show up in the guest... >> >> Device Subchan. DevType CU Type Use PIM PAM POM CHPIDs >> ---------------------------------------------------------------------- >> 0.0.0000 0.0.0000 0000/00 3832/01 yes 80 80 ff 00000000 00000000 >> 0.0.000a 0.0.0001 0000/00 3270/00 80 80 ff 01000000 00000000 >> 0.0.0002 0.0.0002 0000/00 3832/09 yes 80 80 ff 00000000 00000000 >> 0.0.0300 0.0.0003 0000/00 3832/02 yes 80 80 ff 00000000 00000000 >> 0.0.0301 0.0.0004 0000/00 3832/02 yes 80 80 ff 00000000 00000000 >> >> But I would not call it a comprehensive test... > > If you only add the device, it will show up as a normal ccw device in > the guest; i.e. device recognition is done at the same time as for the > other ccw devices. Still good to see that nothing breaks there :) > > To actually make the guest use the 3270 as its console, I guess you > need to explicitly force it (see > https://wiki.qemu.org/Features/3270#Using_3270_as_the_console)... > actually starting the console will almost certainly fail; but you can > at least check whether device recognition in the console path works. > >> >> Mimu, do we have something more elaborate with regards to this? I ran that with success [root@ap01 ~]# lscss | grep 3270 0.0.002a 0.0.0008 0000/00 3270/00 yes 80 80 ff 01000000 00000000 and was able to connect and login. Michael > > I don't think we need extensive testing here; just checking that the > sequence is not fundamentally broken. >