qemu-kvm/SOURCES/kvm-pc-bios-s390-ccw-virtio-Set-missing-status-bits-whil.patch

From 5cf01cccb7501c801fa9f21a021bc9e7d1fc56e3 Mon Sep 17 00:00:00 2001
From: Thomas Huth <thuth@redhat.com>
Date: Fri, 8 Jul 2022 12:29:50 +0200
Subject: [PATCH 33/37] pc-bios/s390-ccw/virtio: Set missing status bits while
 initializing

RH-Author: Thomas Huth <thuth@redhat.com>
RH-MergeRequest: 198: pc-bios/s390-ccw: Fix boot from disks with 4k sectors that do not have the typical DASD geometry
RH-Commit: [5/9] 6072245f49c229518246b4a0d1be360331305bfa
RH-Bugzilla: 2098076
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: David Hildenbrand <david@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>

Bugzilla: http://bugzilla.redhat.com/2098076

commit 175aa06a152ef6b58ba9b2e47a1296b024dea70c
Author: Thomas Huth <thuth@redhat.com>
Date:   Mon Jul 4 13:18:57 2022 +0200

    pc-bios/s390-ccw/virtio: Set missing status bits while initializing

    According chapter "3.1.1 Driver Requirements: Device Initialization"
    of the Virtio specification (v1.1), a driver for a device has to set
    the ACKNOWLEDGE and DRIVER bits in the status field after resetting
    the device. The s390-ccw bios skipped these steps so far and seems
    like QEMU never cared. Anyway, it's better to follow the spec, so
    let's set these bits now in the right spots, too.

    Message-Id: <20220704111903.62400-7-thuth@redhat.com>
    Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
    Reviewed-by: Cornelia Huck <cohuck@redhat.com>
    Reviewed-by: Eric Farman <farman@linux.ibm.com>
    Signed-off-by: Thomas Huth <thuth@redhat.com>

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 pc-bios/s390-ccw/virtio.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
index 5d2c6e3381..4e85a2eb82 100644
--- a/pc-bios/s390-ccw/virtio.c
+++ b/pc-bios/s390-ccw/virtio.c
@@ -220,7 +220,7 @@ int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
 void virtio_setup_ccw(VDev *vdev)
 {
     int i, rc, cfg_size = 0;
-    unsigned char status = VIRTIO_CONFIG_S_DRIVER_OK;
+    uint8_t status;
     struct VirtioFeatureDesc {
         uint32_t features;
         uint8_t index;
@@ -234,6 +234,10 @@ void virtio_setup_ccw(VDev *vdev)
 
     run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0, false);
 
+    status = VIRTIO_CONFIG_S_ACKNOWLEDGE;
+    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
+    IPL_assert(rc == 0, "Could not write ACKNOWLEDGE status to host");
+
     switch (vdev->senseid.cu_model) {
     case VIRTIO_ID_NET:
         vdev->nr_vqs = 2;
@@ -253,6 +257,11 @@ void virtio_setup_ccw(VDev *vdev)
     default:
         panic("Unsupported virtio device\n");
     }
+
+    status |= VIRTIO_CONFIG_S_DRIVER;
+    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
+    IPL_assert(rc == 0, "Could not write DRIVER status to host");
+
     IPL_assert(
         run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size, false) == 0,
        "Could not get block device configuration");
@@ -291,9 +300,10 @@ void virtio_setup_ccw(VDev *vdev)
             run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info), false) == 0,
             "Cannot set VQ info");
     }
-    IPL_assert(
-        run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false) == 0,
-        "Could not write status to host");
+
+    status |= VIRTIO_CONFIG_S_DRIVER_OK;
+    rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
+    IPL_assert(rc == 0, "Could not write DRIVER_OK status to host");
 }
 
 bool virtio_is_supported(SubChannelId schid)
-- 
2.35.3