[PATCH v3 09/19] drivers/hv: create vcpu ioctl

From: Nuno Das Neves
Date: Tue Sep 28 2021 - 14:32:35 EST

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Introduce ioctl for creating a virtual processor in a partition.

Co-developed-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
---
Documentation/virt/mshv/api.rst | 9 +++
drivers/hv/mshv_main.c | 119 +++++++++++++++++++++++++++++++-
include/linux/mshv.h | 10 +++
include/uapi/linux/mshv.h | 5 ++
4 files changed, 142 insertions(+), 1 deletion(-)

diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst
index 71c93b73e999..2538756bc86b 100644
--- a/Documentation/virt/mshv/api.rst
+++ b/Documentation/virt/mshv/api.rst
@@ -87,3 +87,12 @@ memory to stop the pages being moved by Linux in the root partition,
and subsequently being clobbered by the hypervisor. So the region is backed
by real physical memory.

+3.4 MSHV_CREATE_VP
+------------------
+:Type: partition ioctl
+:Parameters: struct mshv_create_vp
+:Returns: vp file descriptor, or -1 on failure
+
+Create a virtual processor in a guest partition, returning a file descriptor to
+represent the vp and perform ioctls on.
+
diff --git a/drivers/hv/mshv_main.c b/drivers/hv/mshv_main.c
index c5c18826a38f..c3ac8c371d0f 100644
--- a/drivers/hv/mshv_main.c
+++ b/drivers/hv/mshv_main.c
@@ -25,6 +25,9 @@ MODULE_LICENSE("GPL");

struct mshv mshv = {};

+static int mshv_vp_release(struct inode *inode, struct file *filp);
+static long mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
+static struct mshv_partition *mshv_partition_get(struct mshv_partition *partition);
static void mshv_partition_put(struct mshv_partition *partition);
static int mshv_partition_release(struct inode *inode, struct file *filp);
static long mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);
@@ -32,6 +35,12 @@ static int mshv_dev_open(struct inode *inode, struct file *filp);
static int mshv_dev_release(struct inode *inode, struct file *filp);
static long mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg);

+static const struct file_operations mshv_vp_fops = {
+ .release = mshv_vp_release,
+ .unlocked_ioctl = mshv_vp_ioctl,
+ .llseek = noop_llseek,
+};
+
static const struct file_operations mshv_partition_fops = {
.release = mshv_partition_release,
.unlocked_ioctl = mshv_partition_ioctl,
@@ -53,6 +62,94 @@ static struct miscdevice mshv_dev = {
.mode = 0600,
};

+static long
+mshv_vp_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+ return -ENOTTY;
+}
+
+static int
+mshv_vp_release(struct inode *inode, struct file *filp)
+{
+ struct mshv_vp *vp = filp->private_data;
+
+ /* Rest of VP cleanup happens in destroy_partition() */
+ mshv_partition_put(vp->partition);
+ return 0;
+}
+
+static long
+mshv_partition_ioctl_create_vp(struct mshv_partition *partition,
+ void __user *arg)
+{
+ struct mshv_create_vp args;
+ struct mshv_vp *vp;
+ struct file *file;
+ int fd;
+ long ret;
+
+ if (copy_from_user(&args, arg, sizeof(args)))
+ return -EFAULT;
+
+ if (args.vp_index >= MSHV_MAX_VPS)
+ return -EINVAL;
+
+ if (partition->vps.array[args.vp_index])
+ return -EEXIST;
+
+ vp = kzalloc(sizeof(*vp), GFP_KERNEL);
+
+ if (!vp)
+ return -ENOMEM;
+
+ vp->index = args.vp_index;
+ vp->partition = mshv_partition_get(partition);
+ if (!vp->partition) {
+ ret = -EBADF;
+ goto free_vp;
+ }
+
+ fd = get_unused_fd_flags(O_CLOEXEC);
+ if (fd < 0) {
+ ret = fd;
+ goto put_partition;
+ }
+
+ file = anon_inode_getfile("mshv_vp", &mshv_vp_fops, vp, O_RDWR);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto put_fd;
+ }
+
+ ret = hv_call_create_vp(
+ NUMA_NO_NODE,
+ partition->id,
+ args.vp_index,
+ 0 /* Only valid for root partition VPs */
+ );
+ if (ret)
+ goto release_file;
+
+ /* already exclusive with the partition mutex for all ioctls */
+ partition->vps.count++;
+ partition->vps.array[args.vp_index] = vp;
+
+ fd_install(fd, file);
+
+ return fd;
+
+release_file:
+ file->f_op->release(file->f_inode, file);
+put_fd:
+ put_unused_fd(fd);
+put_partition:
+ mshv_partition_put(partition);
+free_vp:
+ kfree(vp);
+
+ return ret;
+}
+
static long
mshv_partition_ioctl_map_memory(struct mshv_partition *partition,
struct mshv_user_mem_region __user *user_mem)
@@ -228,6 +325,10 @@ mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
ret = mshv_partition_ioctl_unmap_memory(partition,
(void __user *)arg);
break;
+ case MSHV_CREATE_VP:
+ ret = mshv_partition_ioctl_create_vp(partition,
+ (void __user *)arg);
+ break;
default:
ret = -ENOTTY;
}
@@ -240,6 +341,7 @@ static void
destroy_partition(struct mshv_partition *partition)
{
unsigned long flags, page_count;
+ struct mshv_vp *vp;
struct mshv_mem_region *region;
int i;

@@ -269,9 +371,16 @@ destroy_partition(struct mshv_partition *partition)
hv_call_finalize_partition(partition->id);
/* Withdraw and free all pages we deposited */
hv_call_withdraw_memory(U64_MAX, NUMA_NO_NODE, partition->id);
-
hv_call_delete_partition(partition->id);

+ /* Remove vps */
+ for (i = 0; i < MSHV_MAX_VPS; ++i) {
+ vp = partition->vps.array[i];
+ if (!vp)
+ continue;
+ kfree(vp);
+ }
+
/* Remove regions and unpin the pages */
for (i = 0; i < MSHV_MAX_MEM_REGIONS; ++i) {
region = &partition->regions.slots[i];
@@ -285,6 +394,14 @@ destroy_partition(struct mshv_partition *partition)
kfree(partition);
}

+static struct
+mshv_partition *mshv_partition_get(struct mshv_partition *partition)
+{
+ if (refcount_inc_not_zero(&partition->ref_count))
+ return partition;
+ return NULL;
+}
+
static void
mshv_partition_put(struct mshv_partition *partition)
{
diff --git a/include/linux/mshv.h b/include/linux/mshv.h
index 91a742f37440..50521c5f7948 100644
--- a/include/linux/mshv.h
+++ b/include/linux/mshv.h
@@ -12,6 +12,12 @@

#define MSHV_MAX_PARTITIONS 128
#define MSHV_MAX_MEM_REGIONS 64
+#define MSHV_MAX_VPS 256
+
+struct mshv_vp {
+ u32 index;
+ struct mshv_partition *partition;
+};

struct mshv_mem_region {
u64 size; /* bytes */
@@ -28,6 +34,10 @@ struct mshv_partition {
u32 count;
struct mshv_mem_region slots[MSHV_MAX_MEM_REGIONS];
} regions;
+ struct {
+ u32 count;
+ struct mshv_vp *array[MSHV_MAX_VPS];
+ } vps;
};

struct mshv {
diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index 7ead5f1c8b14..251976348441 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -30,6 +30,10 @@ struct mshv_user_mem_region {
__u32 flags; /* ignored on unmap */
};

+struct mshv_create_vp {
+ __u32 vp_index;
+};
+
#define MSHV_IOCTL 0xB8

/* mshv device */
@@ -39,5 +43,6 @@ struct mshv_user_mem_region {
/* partition device */
#define MSHV_MAP_GUEST_MEMORY _IOW(MSHV_IOCTL, 0x02, struct mshv_user_mem_region)
#define MSHV_UNMAP_GUEST_MEMORY _IOW(MSHV_IOCTL, 0x03, struct mshv_user_mem_region)
+#define MSHV_CREATE_VP _IOW(MSHV_IOCTL, 0x04, struct mshv_create_vp)

#endif
--
2.23.4

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