qemu-s390x
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [qemu-s390x] [PATCH 12/15] s390-bios: Refactor virtio to run channel


From: Jason J. Herne
Subject: Re: [qemu-s390x] [PATCH 12/15] s390-bios: Refactor virtio to run channel programs via cio
Date: Thu, 10 Jan 2019 11:12:47 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1

On 12/14/18 8:04 AM, Cornelia Huck wrote:
On Wed, 12 Dec 2018 09:11:15 -0500
"Jason J. Herne" <address@hidden> wrote:

Now that we have a Channel I/O library let's modify virtio boot code to
make use of it for running channel programs.

Signed-off-by: Jason J. Herne <address@hidden>
---
  pc-bios/s390-ccw/virtio.c | 21 ++-------------------
  1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
index aa9da72..5fb49e2 100644
--- a/pc-bios/s390-ccw/virtio.c
+++ b/pc-bios/s390-ccw/virtio.c
@@ -92,30 +92,13 @@ int drain_irqs(SubChannelId schid)
  static int run_ccw(VDev *vdev, int cmd, void *ptr, int len)
  {
      Ccw1 ccw = {};
-    CmdOrb orb = {};
-    int r;
-
-    enable_subchannel(vdev->schid);
-
-    /* start subchannel command */
-    orb.fmt = 1;
-    orb.cpa = (u32)(long)&ccw;
-    orb.lpm = 0x80;
ccw.cmd_code = cmd;
      ccw.cda = (long)ptr;
      ccw.count = len;
- r = ssch(vdev->schid, &orb);
-    /*
-     * XXX Wait until device is done processing the CCW. For now we can
-     *     assume that a simple tsch will have finished the CCW processing,
-     *     but the architecture allows for asynchronous operation
-     */
-    if (!r) {
-        r = drain_irqs(vdev->schid);
-    }
-    return r;
+    enable_subchannel(vdev->schid);

Preexisting, but I'm wondering why we enable the subchannel here and
not just once?

+    return do_cio(vdev->schid, ptr2u32(&ccw), CCW_FMT1);
  }
static void vring_init(VRing *vr, VqInfo *info)



Good question. It seems to be needed for the net-boot path. Here is the chain:

netmain.c : main()
netmain,c : net_init()
virtio-net.c : virtio_net_init()
virtio.c : virtio_setup_ccw()
virtio.c : run_ccw()

In this case the subchannel would not already be enabled. I suppose I *could* change it, but at this point I'm trying to limit how much more code I'm touching :). This patch set already touches a bit more code than I anticipated. Let me know what your thoughts are.

--
-- Jason J. Herne (address@hidden)




reply via email to

[Prev in Thread] Current Thread [Next in Thread]