[PATCH kvmtool 4/4] virtio/blk: Avoid taking pointer to packed struct

[Andre Przywara <andre.przywara@xxxxxxx>]

clang and GCC9 refuse to compile virtio/blk.c with the following message:
virtio/blk.c:161:37: error: taking address of packed member 'geometry' of class
      or structure 'virtio_blk_config' may result in an unaligned pointer value
      [-Werror,-Waddress-of-packed-member]
        struct virtio_blk_geometry *geo = &conf->geometry;

Since struct virtio_blk_geometry is in a kernel header, we can't do much
about the packed attribute, but as Peter pointed out, the solution is
rather simple: just get rid of the convenience variable and use the
original struct member directly.

Suggested-by: Peter Maydell <peter.maydell@xxxxxxxxxx>
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
---
 virtio/blk.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/virtio/blk.c b/virtio/blk.c
index 50db6f5f..f267be15 100644
--- a/virtio/blk.c
+++ b/virtio/blk.c
@@ -161,7 +161,6 @@ static void set_guest_features(struct kvm *kvm, void *dev, u32 features)
 {
 	struct blk_dev *bdev = dev;
 	struct virtio_blk_config *conf = &bdev->blk_config;
-	struct virtio_blk_geometry *geo = &conf->geometry;
 
 	bdev->features = features;
 
@@ -170,7 +169,8 @@ static void set_guest_features(struct kvm *kvm, void *dev, u32 features)
 	conf->seg_max = virtio_host_to_guest_u32(&bdev->vdev, conf->seg_max);
 
 	/* Geometry */
-	geo->cylinders = virtio_host_to_guest_u16(&bdev->vdev, geo->cylinders);
+	conf->geometry.cylinders = virtio_host_to_guest_u16(&bdev->vdev,
+						conf->geometry.cylinders);
 
 	conf->blk_size = virtio_host_to_guest_u32(&bdev->vdev, conf->blk_size);
 	conf->min_io_size = virtio_host_to_guest_u16(&bdev->vdev, conf->min_io_size);
-- 
2.17.1