[PATCH v3 05/19] drivers/hv: create partition ioctl

From: Nuno Das Neves
Date: Tue Sep 28 2021 - 14:31:48 EST

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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 <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Lillian Grassin-Drake <ligrassi@xxxxxxxxxxxxx>
Signed-off-by: Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx>
---
Documentation/virt/mshv/api.rst | 12 ++
arch/x86/include/asm/hyperv-tlfs.h | 1 +
arch/x86/include/uapi/asm/hyperv-tlfs.h | 124 +++++++++++++++++++++
drivers/hv/mshv_main.c | 141 ++++++++++++++++++++++++
include/asm-generic/hyperv-tlfs.h | 1 +
include/linux/mshv.h | 16 +++
include/uapi/asm-generic/hyperv-tlfs.h | 15 +++
include/uapi/linux/mshv.h | 8 ++
8 files changed, 318 insertions(+)
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 75c5e073ecc0..f92892b27ccc 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").
@@ -58,3 +61,12 @@ number. If not, it will return 0.
The first extension that can be checked is MSHV_CAP_CORE_API_STABLE. This
will be supported when the core API is stable.

+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 606f5cc579b2..2b6f7dca79e6 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..8a5fc59bb33a
--- /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;
+ } __packed;
+ __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;
+ } __packed;
+ __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;
+} __packed;
+
+#endif
diff --git a/drivers/hv/mshv_main.c b/drivers/hv/mshv_main.c
index d73b64ea1448..378bced4044c 100644
--- a/drivers/hv/mshv_main.c
+++ b/drivers/hv/mshv_main.c
@@ -12,15 +12,28 @@
#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");
MODULE_LICENSE("GPL");

+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,
@@ -36,6 +49,130 @@ static struct miscdevice mshv_dev = {
.mode = 0600,
};

+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_check_extension(void __user *user_arg)
{
@@ -58,6 +195,8 @@ mshv_dev_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
switch (ioctl) {
case MSHV_CHECK_EXTENSION:
return mshv_ioctl_check_extension((void __user *)arg);
+ case MSHV_CREATE_PARTITION:
+ return mshv_ioctl_create_partition((void __user *)arg);
}

return -ENOTTY;
@@ -87,6 +226,8 @@ __init mshv_init(void)
if (ret)
pr_err("%s: misc device register failed\n", __func__);

+ spin_lock_init(&mshv.partitions.lock);
+
return ret;
}

diff --git a/include/asm-generic/hyperv-tlfs.h b/include/asm-generic/hyperv-tlfs.h
index 40ff7cdd4a2b..50dc6eafb6a6 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..7a858226a9c5
--- /dev/null
+++ b/include/uapi/asm-generic/hyperv-tlfs.h
@@ -0,0 +1,15 @@
+/* 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
+
+/* Userspace-visible partition creation flags */
+#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 3b84e3ea97be..03b1ed66245d 100644
--- a/include/uapi/linux/mshv.h
+++ b/include/uapi/linux/mshv.h
@@ -9,12 +9,20 @@
*/

#include <linux/types.h>
+#include <asm/hyperv-tlfs.h>
+#include <asm-generic/hyperv-tlfs.h>

#define MSHV_CAP_CORE_API_STABLE 0x0

+struct mshv_create_partition {
+ __u64 flags;
+ struct hv_partition_creation_properties partition_creation_properties;
+};
+
#define MSHV_IOCTL 0xB8

/* mshv device */
#define MSHV_CHECK_EXTENSION _IOW(MSHV_IOCTL, 0x00, __u32)
+#define MSHV_CREATE_PARTITION _IOW(MSHV_IOCTL, 0x01, struct mshv_create_partition)

#endif
--
2.23.4

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