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

From: Nuno Das Neves
Date: Thu Mar 04 2021 - 13:46:11 EST

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On 2/9/2021 5:15 AM, Vitaly Kuznetsov wrote:
> 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.
>

Agreed

>> 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;
>> }
>

Next message: Mathieu Poirier: "Re: [PATCH v5 16/16] rpmsg: char: return an error if device already open"
Previous message: Nuno Das Neves: "Re: [RFC PATCH 04/18] virt/mshv: request version ioctl"
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