virtio: Factor vhost initialization

Move vhost owner and memory table setup to virtio/vhost.c.

This also fixes vsock and SCSI which did not support multiple memory
regions until now (vsock didn't allocate the right region size and would
trigger a buffer overflow).

Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20230606130426.978945-2-jean-philippe@linaro.org
Signed-off-by: Will Deacon <will@kernel.org>

6 files changed, 42 insertions, 75 deletions

diff --git a/Makefile b/Makefile
index ec5f2b35..50c0e28d 100644
--- a/Makefile
+++ b/Makefile
@@ -76,6 +76,7 @@ OBJS	+= virtio/pci.o
 OBJS	+= virtio/vsock.o
 OBJS	+= virtio/pci-legacy.o
 OBJS	+= virtio/pci-modern.o
+OBJS	+= virtio/vhost.o
 OBJS	+= disk/blk.o
 OBJS	+= disk/qcow.o
 OBJS	+= disk/raw.o
diff --git a/include/kvm/virtio.h b/include/kvm/virtio.h
index a8bbaf21..4cc2e3d2 100644
--- a/include/kvm/virtio.h
+++ b/include/kvm/virtio.h
@@ -258,6 +258,7 @@ void virtio_set_guest_features(struct kvm *kvm, struct virtio_device *vdev,
 			       void *dev, u64 features);
 void virtio_notify_status(struct kvm *kvm, struct virtio_device *vdev,
 			  void *dev, u8 status);
+void virtio_vhost_init(struct kvm *kvm, int vhost_fd);
 
 int virtio_transport_parser(const struct option *opt, const char *arg, int unset);
 
diff --git a/virtio/net.c b/virtio/net.c
index bc20ce09..65fdbd17 100644
--- a/virtio/net.c
+++ b/virtio/net.c
@@ -791,40 +791,13 @@ static struct virtio_ops net_dev_virtio_ops = {
 
 static void virtio_net__vhost_init(struct kvm *kvm, struct net_dev *ndev)
 {
-	struct kvm_mem_bank *bank;
-	struct vhost_memory *mem;
-	int r, i;
-
 	ndev->vhost_fd = open("/dev/vhost-net", O_RDWR);
 	if (ndev->vhost_fd < 0)
 		die_perror("Failed openning vhost-net device");
 
-	mem = calloc(1, sizeof(*mem) + kvm->mem_slots * sizeof(struct vhost_memory_region));
-	if (mem == NULL)
-		die("Failed allocating memory for vhost memory map");
-
-	i = 0;
-	list_for_each_entry(bank, &kvm->mem_banks, list) {
-		mem->regions[i] = (struct vhost_memory_region) {
-			.guest_phys_addr = bank->guest_phys_addr,
-			.memory_size	 = bank->size,
-			.userspace_addr	 = (unsigned long)bank->host_addr,
-		};
-		i++;
-	}
-	mem->nregions = i;
-
-	r = ioctl(ndev->vhost_fd, VHOST_SET_OWNER);
-	if (r != 0)
-		die_perror("VHOST_SET_OWNER failed");
-
-	r = ioctl(ndev->vhost_fd, VHOST_SET_MEM_TABLE, mem);
-	if (r != 0)
-		die_perror("VHOST_SET_MEM_TABLE failed");
+	virtio_vhost_init(kvm, ndev->vhost_fd);
 
 	ndev->vdev.use_vhost = true;
-
-	free(mem);
 }
 
 static inline void str_to_mac(const char *str, char *mac)
diff --git a/virtio/scsi.c b/virtio/scsi.c
index 9af8a65c..621a8334 100644
--- a/virtio/scsi.c
+++ b/virtio/scsi.c
@@ -201,7 +201,6 @@ static struct virtio_ops scsi_dev_virtio_ops = {
 
 static void virtio_scsi_vhost_init(struct kvm *kvm, struct scsi_dev *sdev)
 {
-	struct vhost_memory *mem;
 	u64 features;
 	int r;
 
@@ -209,20 +208,7 @@ static void virtio_scsi_vhost_init(struct kvm *kvm, struct scsi_dev *sdev)
 	if (sdev->vhost_fd < 0)
 		die_perror("Failed openning vhost-scsi device");
 
-	mem = calloc(1, sizeof(*mem) + sizeof(struct vhost_memory_region));
-	if (mem == NULL)
-		die("Failed allocating memory for vhost memory map");
-
-	mem->nregions = 1;
-	mem->regions[0] = (struct vhost_memory_region) {
-		.guest_phys_addr	= 0,
-		.memory_size		= kvm->ram_size,
-		.userspace_addr		= (unsigned long)kvm->ram_start,
-	};
-
-	r = ioctl(sdev->vhost_fd, VHOST_SET_OWNER);
-	if (r != 0)
-		die_perror("VHOST_SET_OWNER failed");
+	virtio_vhost_init(kvm, sdev->vhost_fd);
 
 	r = ioctl(sdev->vhost_fd, VHOST_GET_FEATURES, &features);
 	if (r != 0)
@@ -231,13 +217,8 @@ static void virtio_scsi_vhost_init(struct kvm *kvm, struct scsi_dev *sdev)
 	r = ioctl(sdev->vhost_fd, VHOST_SET_FEATURES, &features);
 	if (r != 0)
 		die_perror("VHOST_SET_FEATURES failed");
-	r = ioctl(sdev->vhost_fd, VHOST_SET_MEM_TABLE, mem);
-	if (r != 0)
-		die_perror("VHOST_SET_MEM_TABLE failed");
 
 	sdev->vdev.use_vhost = true;
-
-	free(mem);
 }
 
 
diff --git a/virtio/vhost.c b/virtio/vhost.c
new file mode 100644
index 00000000..f9f72f51
--- /dev/null
+++ b/virtio/vhost.c
@@ -0,0 +1,36 @@
+#include <linux/kvm.h>
+#include <linux/vhost.h>
+#include <linux/list.h>
+#include "kvm/virtio.h"
+
+void virtio_vhost_init(struct kvm *kvm, int vhost_fd)
+{
+	struct kvm_mem_bank *bank;
+	struct vhost_memory *mem;
+	int i = 0, r;
+
+	mem = calloc(1, sizeof(*mem) +
+		     kvm->mem_slots * sizeof(struct vhost_memory_region));
+	if (mem == NULL)
+		die("Failed allocating memory for vhost memory map");
+
+	list_for_each_entry(bank, &kvm->mem_banks, list) {
+		mem->regions[i] = (struct vhost_memory_region) {
+			.guest_phys_addr = bank->guest_phys_addr,
+			.memory_size	 = bank->size,
+			.userspace_addr	 = (unsigned long)bank->host_addr,
+		};
+		i++;
+	}
+	mem->nregions = i;
+
+	r = ioctl(vhost_fd, VHOST_SET_OWNER);
+	if (r != 0)
+		die_perror("VHOST_SET_OWNER failed");
+
+	r = ioctl(vhost_fd, VHOST_SET_MEM_TABLE, mem);
+	if (r != 0)
+		die_perror("VHOST_SET_MEM_TABLE failed");
+
+	free(mem);
+}
diff --git a/virtio/vsock.c b/virtio/vsock.c
index a108e637..4b8be8d7 100644
--- a/virtio/vsock.c
+++ b/virtio/vsock.c
@@ -218,37 +218,14 @@ static struct virtio_ops vsock_dev_virtio_ops = {
 
 static void virtio_vhost_vsock_init(struct kvm *kvm, struct vsock_dev *vdev)
 {
-	struct kvm_mem_bank *bank;
-	struct vhost_memory *mem;
 	u64 features;
-	int r, i;
+	int r;
 
 	vdev->vhost_fd = open("/dev/vhost-vsock", O_RDWR);
 	if (vdev->vhost_fd < 0)
 		die_perror("Failed opening vhost-vsock device");
 
-	mem = calloc(1, sizeof(*mem) + sizeof(struct vhost_memory_region));
-	if (mem == NULL)
-		die("Failed allocating memory for vhost memory map");
-
-	i = 0;
-	list_for_each_entry(bank, &kvm->mem_banks, list) {
-		mem->regions[i] = (struct vhost_memory_region) {
-			.guest_phys_addr = bank->guest_phys_addr,
-			.memory_size	 = bank->size,
-			.userspace_addr	 = (unsigned long)bank->host_addr,
-		};
-		i++;
-	}
-	mem->nregions = i;
-
-	r = ioctl(vdev->vhost_fd, VHOST_SET_OWNER);
-	if (r != 0)
-		die_perror("VHOST_SET_OWNER failed");
-
-	r = ioctl(vdev->vhost_fd, VHOST_SET_MEM_TABLE, mem);
-	if (r != 0)
-		die_perror("VHOST_SET_MEM_TABLE failed");
+	virtio_vhost_init(kvm, vdev->vhost_fd);
 
 	r = ioctl(vdev->vhost_fd, VHOST_GET_FEATURES, &features);
 	if (r != 0)
@@ -263,8 +240,6 @@ static void virtio_vhost_vsock_init(struct kvm *kvm, struct vsock_dev *vdev)
 		die_perror("VHOST_VSOCK_SET_GUEST_CID failed");
 
 	vdev->vdev.use_vhost = true;
-
-	free(mem);
 }
 
 static int virtio_vsock_init_one(struct kvm *kvm, u64 guest_cid)