Use kvm->nr_disks instead of kvm->cfg.image_count

A user can specify multiple disk images using the --disk/-d argument. The
callback for the argument ends up in
disk/core.c::calling disk_img_name_parser(), which increments
kvm->cfg.image_count for each disk image.

Immediately after parsing the arguments in kvm_cmd_run_init(),
kvm->nr_disks is set to kvm->cfg.image_count, effectively making
kvm->nr_disks an alias for kvm->cfg.image_count, as image_count is never
changed afterward.

Later on, the core disk code uses kvm->cfg.image_count when opening all the
disk images, but kvm->nr_disks when closing them, which is inconsistent,
but technically correct since they represent the same thing and have the
same value.

Let's remove all this confusing usage and use only kvm->nr_disks to
represent the number of disk images specified by the user.

While this technically means that kvmtool now supports up to INT_MAX disk
images, in practice this is limited by MAX_DISK_IMAGES, which is equal to
four. Which means there are no functional changes.

Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210923144505.60776-6-alexandru.elisei@arm.com
Signed-off-by: Will Deacon <will@kernel.org>

3 files changed, 9 insertions, 12 deletions

diff --git a/builtin-run.c b/builtin-run.c
index 2a14723b..6822c321 100644
--- a/builtin-run.c
+++ b/builtin-run.c
@@ -526,8 +526,6 @@ static struct kvm *kvm_cmd_run_init(int argc, const char **argv)
 
 	kvm_run_validate_cfg(kvm);
 
-	kvm->nr_disks = kvm->cfg.image_count;
-
 	if (!kvm->cfg.kernel_filename && !kvm->cfg.firmware_filename) {
 		kvm->cfg.kernel_filename = find_kernel();
 
diff --git a/disk/core.c b/disk/core.c
index 8d95c98e..d8d04cb0 100644
--- a/disk/core.c
+++ b/disk/core.c
@@ -16,20 +16,20 @@ int disk_img_name_parser(const struct option *opt, const char *arg, int unset)
 	char *sep;
 	struct kvm *kvm = opt->ptr;
 
-	if (kvm->cfg.image_count >= MAX_DISK_IMAGES)
+	if (kvm->nr_disks >= MAX_DISK_IMAGES)
 		die("Currently only 4 images are supported");
 
-	kvm->cfg.disk_image[kvm->cfg.image_count].filename = arg;
+	kvm->cfg.disk_image[kvm->nr_disks].filename = arg;
 	cur = arg;
 
 	if (strncmp(arg, "scsi:", 5) == 0) {
 		sep = strstr(arg, ":");
 		if (sep)
-			kvm->cfg.disk_image[kvm->cfg.image_count].wwpn = sep + 1;
+			kvm->cfg.disk_image[kvm->nr_disks].wwpn = sep + 1;
 		sep = strstr(sep + 1, ":");
 		if (sep) {
 			*sep = 0;
-			kvm->cfg.disk_image[kvm->cfg.image_count].tpgt = sep + 1;
+			kvm->cfg.disk_image[kvm->nr_disks].tpgt = sep + 1;
 		}
 		cur = sep + 1;
 	}
@@ -38,15 +38,15 @@ int disk_img_name_parser(const struct option *opt, const char *arg, int unset)
 		sep = strstr(cur, ",");
 		if (sep) {
 			if (strncmp(sep + 1, "ro", 2) == 0)
-				kvm->cfg.disk_image[kvm->cfg.image_count].readonly = true;
+				kvm->cfg.disk_image[kvm->nr_disks].readonly = true;
 			else if (strncmp(sep + 1, "direct", 6) == 0)
-				kvm->cfg.disk_image[kvm->cfg.image_count].direct = true;
+				kvm->cfg.disk_image[kvm->nr_disks].direct = true;
 			*sep = 0;
 			cur = sep + 1;
 		}
 	} while (sep);
 
-	kvm->cfg.image_count++;
+	kvm->nr_disks++;
 
 	return 0;
 }
@@ -152,7 +152,7 @@ static struct disk_image **disk_image__open_all(struct kvm *kvm)
 	void *err;
 	int i;
 	struct disk_image_params *params = (struct disk_image_params *)&kvm->cfg.disk_image;
-	int count = kvm->cfg.image_count;
+	int count = kvm->nr_disks;
 
 	if (!count)
 		return ERR_PTR(-EINVAL);
@@ -328,7 +328,7 @@ void disk_image__set_callback(struct disk_image *disk,
 
 int disk_image__init(struct kvm *kvm)
 {
-	if (kvm->cfg.image_count) {
+	if (kvm->nr_disks) {
 		kvm->disks = disk_image__open_all(kvm);
 		if (IS_ERR(kvm->disks))
 			return PTR_ERR(kvm->disks);
diff --git a/include/kvm/kvm-config.h b/include/kvm/kvm-config.h
index 8b6c1511..35d45c0f 100644
--- a/include/kvm/kvm-config.h
+++ b/include/kvm/kvm-config.h
@@ -23,7 +23,6 @@ struct kvm_config {
 	struct disk_image_params disk_image[MAX_DISK_IMAGES];
 	struct vfio_device_params *vfio_devices;
 	u64 ram_size;
-	u8  image_count;
 	u8 num_net_devices;
 	u8 num_vfio_devices;
 	u64 vsock_cid;