Re: [RFC PATCH 05/18] virt/mshv: create partition ioctl

From: Vitaly Kuznetsov
Date: Tue Feb 09 2021 - 08:17:34 EST

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Nuno Das Neves <nunodasneves@xxxxxxxxxxxxxxxxxxx> writes:

> 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 ++++++++++++++++
> 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,
> -};
> -

This looks like an unneeded code churn as these structs just got added a
few patches ago. It would probably be possible to put it to the right
place from the very beginning so you don't need to move it in this
patch.

> 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;
> }

--
Vitaly

Next message: Michal Hocko: "Re: [PATCH v17 07/10] mm: introduce memfd_secret system call to create "secret" memory areas"
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