[PATCH kvmtool 2/4] virtio: Factor out base features for modern virtio transports

[Will Deacon <will@kernel.org>]

In preparation for optionally enabling VIRTIO_F_ACCESS_PLATFORM,
factor out the base features for modern virtio transports.

Signed-off-by: Will Deacon <will@kernel.org>
---
 include/kvm/virtio.h | 1 +
 virtio/core.c        | 7 +++++++
 virtio/mmio-modern.c | 2 +-
 virtio/pci-modern.c  | 2 +-
 4 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/include/kvm/virtio.h b/include/kvm/virtio.h
index 8b7ec1b..c95183b 100644
--- a/include/kvm/virtio.h
+++ b/include/kvm/virtio.h
@@ -277,5 +277,6 @@ void virtio_vhost_reset_vring(struct kvm *kvm, int vhost_fd, u32 index,
 int virtio_vhost_set_features(int vhost_fd, u64 features);
 
 int virtio_transport_parser(const struct option *opt, const char *arg, int unset);
+u64 virtio_get_modern_transport_features(void);
 
 #endif /* KVM__VIRTIO_H */
diff --git a/virtio/core.c b/virtio/core.c
index 50c9ddd..8c5086d 100644
--- a/virtio/core.c
+++ b/virtio/core.c
@@ -353,6 +353,13 @@ bool virtio_access_config(struct kvm *kvm, struct virtio_device *vdev,
 	return true;
 }
 
+static u64 virtio_modern_transport_features = 1ULL << VIRTIO_F_VERSION_1;
+
+u64 virtio_get_modern_transport_features(void)
+{
+	return virtio_modern_transport_features;
+}
+
 int virtio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		struct virtio_ops *ops, enum virtio_trans trans,
 		int device_id, int subsys_id, int class)
diff --git a/virtio/mmio-modern.c b/virtio/mmio-modern.c
index 6c0bb38..7787508 100644
--- a/virtio/mmio-modern.c
+++ b/virtio/mmio-modern.c
@@ -11,7 +11,7 @@ static void virtio_mmio_config_in(struct kvm_cpu *vcpu,
 				  struct virtio_device *vdev)
 {
 	struct virtio_mmio *vmmio = vdev->virtio;
-	u64 features = 1ULL << VIRTIO_F_VERSION_1;
+	u64 features = virtio_get_modern_transport_features();
 	u32 val = 0;
 
 	switch (addr) {
diff --git a/virtio/pci-modern.c b/virtio/pci-modern.c
index ef2f3e2..888afa5 100644
--- a/virtio/pci-modern.c
+++ b/virtio/pci-modern.c
@@ -148,7 +148,7 @@ static bool virtio_pci__common_read(struct virtio_device *vdev,
 {
 	u32 val;
 	struct virtio_pci *vpci = vdev->virtio;
-	u64 features = 1ULL << VIRTIO_F_VERSION_1;
+	u64 features = virtio_get_modern_transport_features();
 
 	switch (offset - VPCI_CFG_COMMON_START) {
 	case VIRTIO_PCI_COMMON_DFSELECT:
-- 
2.55.0.rc0.738.g0c8ab3ebcc-goog