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Re: [Qemu-block] [Qemu-devel] [PATCH v4 1/1] virtio-scsi-ccw: use ioeven

From: QingFeng Hao
Subject: Re: [Qemu-block] [Qemu-devel] [PATCH v4 1/1] virtio-scsi-ccw: use ioeventfd even when KVM is disabled
Date: Wed, 5 Jul 2017 09:56:30 +0800
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1

在 2017/7/4 22:04, Christian Borntraeger 写道:
On 07/04/2017 03:23 PM, QingFeng Hao wrote:
This patch is based on a similar patch from Stefan Hajnoczi -
commit c324fd0a39c ("virtio-pci: use ioeventfd even when KVM is disabled")

Do not check kvm_eventfds_enabled() when KVM is disabled since it
always returns 0.  Since commit 8c56c1a592b5092d91da8d8943c17777d6462a6f
("memory: emulate ioeventfd") it has been possible to use ioeventfds in
qtest or TCG mode.

This patch makes -device virtio-scsi-ccw,iothread=iothread0 work even
when KVM is disabled.
Currently we don't have an equivalent to "memory: emulate ioeventfd"
for ccw yet, but that this doesn't hurt and qemu-iotests 068 can pass with
skipping iothread arguments.

I have tested that virtio-scsi-ccw works under tcg both with and without

This patch fixes qemu-iotests 068, which was accidentally merged early
despite the dependency on ioeventfd.

Signed-off-by: QingFeng Hao <address@hidden>
Reviewed-by: Cornelia Huck <address@hidden>
I will take it via the s390-next tree.

thanks applied.
Ok, thanks.
  hw/s390x/virtio-ccw.c | 2 +-
  target/s390x/cpu.h    | 6 +++++-
  2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 90d37cb9ff..35896eb007 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -711,7 +711,7 @@ static void virtio_ccw_device_realize(VirtioCcwDevice *dev, 
Error **errp)
          sch->cssid, sch->ssid, sch->schid, sch->devno,
          ccw_dev->devno.valid ? "user-configured" : "auto-configured");

-    if (!kvm_eventfds_enabled()) {
+    if (kvm_enabled() && !kvm_eventfds_enabled()) {
          dev->flags &= ~VIRTIO_CCW_FLAG_USE_IOEVENTFD;

diff --git a/target/s390x/cpu.h b/target/s390x/cpu.h
index 9faca04b52..bdb9bdbc9d 100644
--- a/target/s390x/cpu.h
+++ b/target/s390x/cpu.h
@@ -1264,7 +1264,11 @@ static inline int 
s390_assign_subch_ioeventfd(EventNotifier *notifier,
                                                uint32_t sch_id, int vq,
                                                bool assign)
-    return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
+    if (kvm_enabled()) {
+        return kvm_s390_assign_subch_ioeventfd(notifier, sch_id, vq, assign);
+    } else {
+        return 0;
+    }

  static inline void s390_crypto_reset(void)

QingFeng Hao

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