Add MSHV_CREATE_PARTITION, which creates an fd to track a new partition.
Partition is not yet created in the hypervisor itself.
Introduce header files for userspace-facing hyperv structures.

Co-developed-by: Lillian Grassin-Drake <redacted>
Signed-off-by: Lillian Grassin-Drake <redacted>
Signed-off-by: Nuno Das Neves <redacted>
---
 Documentation/virt/mshv/api.rst         |  12 ++
 arch/x86/include/asm/hyperv-tlfs.h      |   1 +
 arch/x86/include/uapi/asm/hyperv-tlfs.h | 124 ++++++++++++++++
 include/asm-generic/hyperv-tlfs.h       |   1 +
 include/linux/mshv.h                    |  16 +++
 include/uapi/asm-generic/hyperv-tlfs.h  |  14 ++
 include/uapi/linux/mshv.h               |   7 +
 virt/mshv/mshv_main.c                   | 179 +++++++++++++++++++++---
 8 files changed, 338 insertions(+), 16 deletions(-)
 create mode 100644 arch/x86/include/uapi/asm/hyperv-tlfs.h
 create mode 100644 include/uapi/asm-generic/hyperv-tlfs.h

diff --git a/Documentation/virt/mshv/api.rst b/Documentation/virt/mshv/api.rst
index 82e32de48d03..ce651a1738e0 100644
--- a/Documentation/virt/mshv/api.rst
+++ b/Documentation/virt/mshv/api.rst

@@ -39,6 +39,9 @@ root partition can use mshv APIs to create guest partitions.
 
 The module is named mshv and can be configured with CONFIG_HYPERV_ROOT_API.
 
+The uapi header files you need are linux/mshv.h, asm/hyperv-tlfs.h, and
+asm-generic/hyperv-tlfs.h.
+
 Mshv is file descriptor-based, following a similar pattern to KVM.
 
 To get a handle to the mshv driver, use open("/dev/mshv").

@@ -60,3 +63,12 @@ if one of them matches.
 This /dev/mshv file descriptor will remain 'locked' to that version as long as
 it is open - this ioctl can only be called once per open.
 
+3.2 MSHV_CREATE_PARTITION
+-------------------------
+:Type: /dev/mshv ioctl
+:Parameters: struct mshv_create_partition
+:Returns: partition file descriptor, or -1 on failure
+
+This ioctl creates a guest partition, returning a file descriptor to use as a
+handle for partition ioctls.
+

diff --git a/arch/x86/include/asm/hyperv-tlfs.h b/arch/x86/include/asm/hyperv-tlfs.h
index 592c75e51e0f..4cd44ae9bffb 100644
--- a/arch/x86/include/asm/hyperv-tlfs.h
+++ b/arch/x86/include/asm/hyperv-tlfs.h

@@ -11,6 +11,7 @@
 
 #include <linux/types.h>
 #include <asm/page.h>
+#include <uapi/asm/hyperv-tlfs.h>
 /*
  * The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
  * is set by CPUID(HvCpuIdFunctionVersionAndFeatures).

diff --git a/arch/x86/include/uapi/asm/hyperv-tlfs.h b/arch/x86/include/uapi/asm/hyperv-tlfs.h
new file mode 100644
index 000000000000..72150c25ffe6
--- /dev/null
+++ b/arch/x86/include/uapi/asm/hyperv-tlfs.h

@@ -0,0 +1,124 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_X86_HYPERV_TLFS_USER_H
+#define _UAPI_ASM_X86_HYPERV_TLFS_USER_H
+
+#include <linux/types.h>
+
+#define HV_PARTITION_PROCESSOR_FEATURE_BANKS 2
+
+union hv_partition_processor_features {
+	struct {
+		__u64 sse3_support:1;
+		__u64 lahf_sahf_support:1;
+		__u64 ssse3_support:1;
+		__u64 sse4_1_support:1;
+		__u64 sse4_2_support:1;
+		__u64 sse4a_support:1;
+		__u64 xop_support:1;
+		__u64 pop_cnt_support:1;
+		__u64 cmpxchg16b_support:1;
+		__u64 altmovcr8_support:1;
+		__u64 lzcnt_support:1;
+		__u64 mis_align_sse_support:1;
+		__u64 mmx_ext_support:1;
+		__u64 amd3dnow_support:1;
+		__u64 extended_amd3dnow_support:1;
+		__u64 page_1gb_support:1;
+		__u64 aes_support:1;
+		__u64 pclmulqdq_support:1;
+		__u64 pcid_support:1;
+		__u64 fma4_support:1;
+		__u64 f16c_support:1;
+		__u64 rd_rand_support:1;
+		__u64 rd_wr_fs_gs_support:1;
+		__u64 smep_support:1;
+		__u64 enhanced_fast_string_support:1;
+		__u64 bmi1_support:1;
+		__u64 bmi2_support:1;
+		__u64 hle_support_deprecated:1;
+		__u64 rtm_support_deprecated:1;
+		__u64 movbe_support:1;
+		__u64 npiep1_support:1;
+		__u64 dep_x87_fpu_save_support:1;
+		__u64 rd_seed_support:1;
+		__u64 adx_support:1;
+		__u64 intel_prefetch_support:1;
+		__u64 smap_support:1;
+		__u64 hle_support:1;
+		__u64 rtm_support:1;
+		__u64 rdtscp_support:1;
+		__u64 clflushopt_support:1;
+		__u64 clwb_support:1;
+		__u64 sha_support:1;
+		__u64 x87_pointers_saved_support:1;
+		__u64 invpcid_support:1;
+		__u64 ibrs_support:1;
+		__u64 stibp_support:1;
+		__u64 ibpb_support: 1;
+		__u64 unrestricted_guest_support:1;
+		__u64 mdd_support:1;
+		__u64 fast_short_rep_mov_support:1;
+		__u64 l1dcache_flush_support:1;
+		__u64 rdcl_no_support:1;
+		__u64 ibrs_all_support:1;
+		__u64 skip_l1df_support:1;
+		__u64 ssb_no_support:1;
+		__u64 rsb_a_no_support:1;
+		__u64 virt_spec_ctrl_support:1;
+		__u64 rd_pid_support:1;
+		__u64 umip_support:1;
+		__u64 mbs_no_support:1;
+		__u64 mb_clear_support:1;
+		__u64 taa_no_support:1;
+		__u64 tsx_ctrl_support:1;
+		/*
+		 * N.B. The final processor feature bit in bank 0 is reserved to
+		 * simplify potential downlevel backports.
+		 */
+		__u64 reserved_bank0:1;
+
+		/* N.B. Begin bank 1 processor features. */
+		__u64 acount_mcount_support:1;
+		__u64 tsc_invariant_support:1;
+		__u64 cl_zero_support:1;
+		__u64 rdpru_support:1;
+		__u64 la57_support:1;
+		__u64 mbec_support:1;
+		__u64 nested_virt_support:1;
+		__u64 psfd_support:1;
+		__u64 cet_ss_support:1;
+		__u64 cet_ibt_support:1;
+		__u64 vmx_exception_inject_support:1;
+		__u64 enqcmd_support:1;
+		__u64 umwait_tpause_support:1;
+		__u64 movdiri_support:1;
+		__u64 movdir64b_support:1;
+		__u64 cldemote_support:1;
+		__u64 serialize_support:1;
+		__u64 tsc_deadline_tmr_support:1;
+		__u64 tsc_adjust_support:1;
+		__u64 fzlrep_movsb:1;
+		__u64 fsrep_stosb:1;
+		__u64 fsrep_cmpsb:1;
+		__u64 reserved_bank1:42;
+	};
+	__u64 as_uint64[HV_PARTITION_PROCESSOR_FEATURE_BANKS];
+};
+
+union hv_partition_processor_xsave_features {
+	struct {
+		__u64 xsave_support : 1;
+		__u64 xsaveopt_support : 1;
+		__u64 avx_support : 1;
+		__u64 reserved1 : 61;
+	};
+	__u64 as_uint64;
+};
+
+struct hv_partition_creation_properties {
+	union hv_partition_processor_features disabled_processor_features;
+	union hv_partition_processor_xsave_features
+		disabled_processor_xsave_features;
+};
+
+#endif

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 05b9dc9896ab..2ff580780ce4 100644
--- a/include/asm-generic/hyperv-tlfs.h
+++ b/include/asm-generic/hyperv-tlfs.h

@@ -12,6 +12,7 @@
 #include <linux/types.h>
 #include <linux/bits.h>
 #include <linux/time64.h>
+#include <uapi/asm-generic/hyperv-tlfs.h>
 
 /*
  * While not explicitly listed in the TLFS, Hyper-V always runs with a page size

diff --git a/include/linux/mshv.h b/include/linux/mshv.h
index a0982fe2c0b8..fc4f35089b2c 100644
--- a/include/linux/mshv.h
+++ b/include/linux/mshv.h

@@ -6,6 +6,22 @@
  * Microsoft Hypervisor root partition driver for /dev/mshv
  */
 
+#include <linux/spinlock.h>
 #include <uapi/linux/mshv.h>
 
+#define MSHV_MAX_PARTITIONS		128
+
+struct mshv_partition {
+	u64 id;
+	refcount_t ref_count;
+};
+
+struct mshv {
+	struct {
+		spinlock_t lock;
+		u64 count;
+		struct mshv_partition *array[MSHV_MAX_PARTITIONS];
+	} partitions;
+};
+
 #endif

diff --git a/include/uapi/asm-generic/hyperv-tlfs.h b/include/uapi/asm-generic/hyperv-tlfs.h
new file mode 100644
index 000000000000..140cc0b4f98f
--- /dev/null
+++ b/include/uapi/asm-generic/hyperv-tlfs.h

@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_ASM_GENERIC_HYPERV_TLFS_USER_H
+#define _UAPI_ASM_GENERIC_HYPERV_TLFS_USER_H
+
+#ifndef BIT
+#define BIT(X)	(1ULL << (X))
+#endif
+
+#define HV_PARTITION_CREATION_FLAG_SMT_ENABLED_GUEST                BIT(0)
+#define HV_PARTITION_CREATION_FLAG_GPA_LARGE_PAGES_DISABLED         BIT(3)
+#define HV_PARTITION_CREATION_FLAG_GPA_SUPER_PAGES_ENABLED          BIT(4)
+#define HV_PARTITION_CREATION_FLAG_LAPIC_ENABLED                    BIT(13)
+
+#endif

diff --git a/include/uapi/linux/mshv.h b/include/uapi/linux/mshv.h
index dd30fc2f0a80..3788f8bc5caa 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h

@@ -8,12 +8,19 @@
  */
 
 #include <linux/types.h>
+#include <asm/hyperv-tlfs.h>
 
 #define MSHV_VERSION	0x0
 
+struct mshv_create_partition {
+	__u64 flags;
+	struct hv_partition_creation_properties partition_creation_properties;
+};
+
 #define MSHV_IOCTL 0xB8
 
 /* mshv device */
 #define MSHV_REQUEST_VERSION	_IOW(MSHV_IOCTL, 0x00, __u32)
+#define MSHV_CREATE_PARTITION	_IOW(MSHV_IOCTL, 0x01, struct mshv_create_partition)
 
 #endif

diff --git a/virt/mshv/mshv_main.c b/virt/mshv/mshv_main.c
index 62f631f85301..4dcbe4907430 100644
--- a/virt/mshv/mshv_main.c
+++ b/virt/mshv/mshv_main.c

@@ -12,6 +12,8 @@
 #include <linux/fs.h>
 #include <linux/miscdevice.h>
 #include <linux/slab.h>
+#include <linux/file.h>
+#include <linux/anon_inodes.h>
 #include <linux/mshv.h>
 
 MODULE_AUTHOR("Microsoft");

@@ -24,6 +26,161 @@ static u32 supported_versions[] = {
 	MSHV_CURRENT_VERSION,
 };
 
+static struct mshv mshv = {};
+
+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);
+
+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_partition_fops = {
+	.release = mshv_partition_release,
+	.unlocked_ioctl = mshv_partition_ioctl,
+	.llseek = noop_llseek,
+};
+
+static const struct file_operations mshv_dev_fops = {
+	.owner = THIS_MODULE,
+	.open = mshv_dev_open,
+	.release = mshv_dev_release,
+	.unlocked_ioctl = mshv_dev_ioctl,
+	.llseek = noop_llseek,
+};
+
+static struct miscdevice mshv_dev = {
+	.minor = MISC_DYNAMIC_MINOR,
+	.name = "mshv",
+	.fops = &mshv_dev_fops,
+	.mode = 600,
+};
+
+static long
+mshv_partition_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
+{
+	return -ENOTTY;
+}
+
+static void
+destroy_partition(struct mshv_partition *partition)
+{
+	unsigned long flags;
+	int i;
+
+	/* Remove from list of partitions */
+	spin_lock_irqsave(&mshv.partitions.lock, flags);
+
+	for (i = 0; i < MSHV_MAX_PARTITIONS; ++i) {
+		if (mshv.partitions.array[i] == partition)
+			break;
+	}
+
+	if (i == MSHV_MAX_PARTITIONS) {
+		pr_err("%s: failed to locate partition in array\n", __func__);
+	} else {
+		mshv.partitions.count--;
+		mshv.partitions.array[i] = NULL;
+	}
+
+	spin_unlock_irqrestore(&mshv.partitions.lock, flags);
+
+	kfree(partition);
+}
+
+static void
+mshv_partition_put(struct mshv_partition *partition)
+{
+	if (refcount_dec_and_test(&partition->ref_count))
+		destroy_partition(partition);
+}
+
+static int
+mshv_partition_release(struct inode *inode, struct file *filp)
+{
+	struct mshv_partition *partition = filp->private_data;
+
+	mshv_partition_put(partition);
+
+	return 0;
+}
+
+static int
+add_partition(struct mshv_partition *partition)
+{
+	unsigned long flags;
+	int i, ret = 0;
+
+	spin_lock_irqsave(&mshv.partitions.lock, flags);
+
+	if (mshv.partitions.count >= MSHV_MAX_PARTITIONS) {
+		pr_err("%s: too many partitions\n", __func__);
+		ret = -ENOSPC;
+		goto out_unlock;
+	}
+
+	for (i = 0; i < MSHV_MAX_PARTITIONS; ++i) {
+		if (!mshv.partitions.array[i])
+			break;
+	}
+
+	mshv.partitions.count++;
+	mshv.partitions.array[i] = partition;
+
+out_unlock:
+	spin_unlock_irqrestore(&mshv.partitions.lock, flags);
+
+	return ret;
+}
+
+static long
+mshv_ioctl_create_partition(void __user *user_arg)
+{
+	struct mshv_create_partition args;
+	struct mshv_partition *partition;
+	struct file *file;
+	int fd;
+	long ret;
+
+	if (copy_from_user(&args, user_arg, sizeof(args)))
+		return -EFAULT;
+
+	partition = kzalloc(sizeof(*partition), GFP_KERNEL);
+	if (!partition)
+		return -ENOMEM;
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0) {
+		ret = fd;
+		goto free_partition;
+	}
+
+	file = anon_inode_getfile("mshv_partition", &mshv_partition_fops,
+				  partition, O_RDWR);
+	if (IS_ERR(file)) {
+		ret = PTR_ERR(file);
+		goto put_fd;
+	}
+	refcount_set(&partition->ref_count, 1);
+
+	ret = add_partition(partition);
+	if (ret)
+		goto release_file;
+
+	fd_install(fd, file);
+
+	return fd;
+
+release_file:
+	file->f_op->release(file->f_inode, file);
+put_fd:
+	put_unused_fd(fd);
+free_partition:
+	kfree(partition);
+	return ret;
+}
+
 static long
 mshv_ioctl_request_version(u32 *version, void __user *user_arg)
 {

@@ -59,7 +216,10 @@ mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 	if (*version == MSHV_INVALID_VERSION)
 		return -EBADFD;
 
-	/* TODO other ioctls */
+	switch (ioctl) {
+	case MSHV_CREATE_PARTITION:
+		return mshv_ioctl_create_partition((void __user *)arg);
+	}
 
 	return -ENOTTY;
 }

@@ -82,21 +242,6 @@ mshv_dev_release(struct inode *inode, struct file *filp)
 	return 0;
 }
 
-static const struct file_operations mshv_dev_fops = {
-	.owner = THIS_MODULE,
-	.open = mshv_dev_open,
-	.release = mshv_dev_release,
-	.unlocked_ioctl = mshv_dev_ioctl,
-	.llseek = noop_llseek,
-};
-
-static struct miscdevice mshv_dev = {
-	.minor = MISC_DYNAMIC_MINOR,
-	.name = "mshv",
-	.fops = &mshv_dev_fops,
-	.mode = 600,
-};
-

 static int
 __init mshv_init(void)
 {

@@ -106,6 +251,8 @@ __init mshv_init(void)
 	if (r)
 		pr_err("%s: misc device register failed\n", __func__);
 
+	spin_lock_init(&mshv.partitions.lock);
+
 	return r;
 }