On 2/8/2021 11:47 AM, Michael Kelley wrote:
> From: Nuno Das Neves <[email protected]> Sent: Friday, 
> November 20, 2020 4:31 PM
>>
>> Same idea as synic setup in drivers/hv/hv.c:hv_synic_enable_regs()
>> and hv_synic_disable_regs().
>> Setting up synic registers in both vmbus driver and mshv would clobber
>> them, but the vmbus driver will not run in the root partition, so this
>> is safe.
>>
>> Co-developed-by: Lillian Grassin-Drake <[email protected]>
>> Signed-off-by: Lillian Grassin-Drake <[email protected]>
>> Signed-off-by: Nuno Das Neves <[email protected]>
>> ---
>>  arch/x86/include/asm/hyperv-tlfs.h      |  29 ---
>>  arch/x86/include/uapi/asm/hyperv-tlfs.h | 264 ++++++++++++++++++++++++
>>  include/asm-generic/hyperv-tlfs.h       |  46 +----
>>  include/linux/mshv.h                    |   1 +
>>  include/uapi/asm-generic/hyperv-tlfs.h  |  43 ++++
>>  virt/mshv/mshv_main.c                   |  98 ++++++++-
>>  6 files changed, 404 insertions(+), 77 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/hyperv-tlfs.h 
>> b/arch/x86/include/asm/hyperv-tlfs.h
>> index 4cd44ae9bffb..c34a6bb4f457 100644
>> --- a/arch/x86/include/asm/hyperv-tlfs.h
>> +++ b/arch/x86/include/asm/hyperv-tlfs.h
>> @@ -267,35 +267,6 @@ struct hv_tsc_emulation_status {
>>  #define HV_X64_MSR_TSC_REFERENCE_ENABLE             0x00000001
>>  #define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT      12
>>
>> -
>> -/* Define hypervisor message types. */
>> -enum hv_message_type {
>> -    HVMSG_NONE                      = 0x00000000,
>> -
>> -    /* Memory access messages. */
>> -    HVMSG_UNMAPPED_GPA              = 0x80000000,
>> -    HVMSG_GPA_INTERCEPT             = 0x80000001,
>> -
>> -    /* Timer notification messages. */
>> -    HVMSG_TIMER_EXPIRED             = 0x80000010,
>> -
>> -    /* Error messages. */
>> -    HVMSG_INVALID_VP_REGISTER_VALUE = 0x80000020,
>> -    HVMSG_UNRECOVERABLE_EXCEPTION   = 0x80000021,
>> -    HVMSG_UNSUPPORTED_FEATURE       = 0x80000022,
>> -
>> -    /* Trace buffer complete messages. */
>> -    HVMSG_EVENTLOG_BUFFERCOMPLETE   = 0x80000040,
>> -
>> -    /* Platform-specific processor intercept messages. */
>> -    HVMSG_X64_IOPORT_INTERCEPT      = 0x80010000,
>> -    HVMSG_X64_MSR_INTERCEPT         = 0x80010001,
>> -    HVMSG_X64_CPUID_INTERCEPT       = 0x80010002,
>> -    HVMSG_X64_EXCEPTION_INTERCEPT   = 0x80010003,
>> -    HVMSG_X64_APIC_EOI              = 0x80010004,
>> -    HVMSG_X64_LEGACY_FP_ERROR       = 0x80010005
>> -};
>> -
>>  struct hv_nested_enlightenments_control {
>>      struct {
>>              __u32 directhypercall:1;
>> diff --git a/arch/x86/include/uapi/asm/hyperv-tlfs.h 
>> b/arch/x86/include/uapi/asm/hyperv-
>> tlfs.h
>> index 2ff655962738..c6a27053f791 100644
>> --- a/arch/x86/include/uapi/asm/hyperv-tlfs.h
>> +++ b/arch/x86/include/uapi/asm/hyperv-tlfs.h
>> @@ -722,4 +722,268 @@ union hv_register_value {
>>              pending_virtualization_fault_event;
>>  };
>>
>> +/* Define hypervisor message types. */
>> +enum hv_message_type {
>> +    HVMSG_NONE                              = 0x00000000,
>> +
>> +    /* Memory access messages. */
>> +    HVMSG_UNMAPPED_GPA                      = 0x80000000,
>> +    HVMSG_GPA_INTERCEPT                     = 0x80000001,
>> +
>> +    /* Timer notification messages. */
>> +    HVMSG_TIMER_EXPIRED                     = 0x80000010,
>> +
>> +    /* Error messages. */
>> +    HVMSG_INVALID_VP_REGISTER_VALUE         = 0x80000020,
>> +    HVMSG_UNRECOVERABLE_EXCEPTION           = 0x80000021,
>> +    HVMSG_UNSUPPORTED_FEATURE               = 0x80000022,
>> +
>> +    /* Trace buffer complete messages. */
>> +    HVMSG_EVENTLOG_BUFFERCOMPLETE           = 0x80000040,
>> +
>> +    /* Platform-specific processor intercept messages. */
>> +    HVMSG_X64_IO_PORT_INTERCEPT             = 0x80010000,
>> +    HVMSG_X64_MSR_INTERCEPT                 = 0x80010001,
>> +    HVMSG_X64_CPUID_INTERCEPT               = 0x80010002,
>> +    HVMSG_X64_EXCEPTION_INTERCEPT           = 0x80010003,
>> +    HVMSG_X64_APIC_EOI                      = 0x80010004,
>> +    HVMSG_X64_LEGACY_FP_ERROR               = 0x80010005,
>> +    HVMSG_X64_IOMMU_PRQ                     = 0x80010006,
>> +    HVMSG_X64_HALT                          = 0x80010007,
>> +    HVMSG_X64_INTERRUPTION_DELIVERABLE      = 0x80010008,
>> +    HVMSG_X64_SIPI_INTERCEPT                = 0x80010009,
>> +};
> 
> I have a separate patch series that moves this enum to the
> asm-generic portion of hyperv-tlfs.h because there's not a good way
> to separate the arch neutral from arch dependent values.
> 

Ok, but it should also be changed to #define instead of an enum, right?
I will do that in this patch.
This requires a couple of changes in other files in drivers/hv
where this enum is used.

>> +
>> +
>> +union hv_x64_vp_execution_state {
>> +    __u16 as_uint16;
>> +    struct {
>> +            __u16 cpl:2;
>> +            __u16 cr0_pe:1;
>> +            __u16 cr0_am:1;
>> +            __u16 efer_lma:1;
>> +            __u16 debug_active:1;
>> +            __u16 interruption_pending:1;
>> +            __u16 vtl:4;
>> +            __u16 enclave_mode:1;
>> +            __u16 interrupt_shadow:1;
>> +            __u16 virtualization_fault_active:1;
>> +            __u16 reserved:2;
>> +    };
>> +};
>> +
>> +/* Values for intercept_access_type field */
>> +#define HV_INTERCEPT_ACCESS_READ    0
>> +#define HV_INTERCEPT_ACCESS_WRITE   1
>> +#define HV_INTERCEPT_ACCESS_EXECUTE 2
>> +
>> +struct hv_x64_intercept_message_header {
>> +    __u32 vp_index;
>> +    __u8 instruction_length:4;
>> +    __u8 cr8:4; // only set for exo partitions
>> +    __u8 intercept_access_type;
>> +    union hv_x64_vp_execution_state execution_state;
>> +    struct hv_x64_segment_register cs_segment;
>> +    __u64 rip;
>> +    __u64 rflags;
>> +};
>> +
>> +#define HV_HYPERCALL_INTERCEPT_MAX_XMM_REGISTERS 6
>> +
>> +struct hv_x64_hypercall_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u64 rax;
>> +    __u64 rbx;
>> +    __u64 rcx;
>> +    __u64 rdx;
>> +    __u64 r8;
>> +    __u64 rsi;
>> +    __u64 rdi;
>> +    struct hv_u128 xmmregisters[HV_HYPERCALL_INTERCEPT_MAX_XMM_REGISTERS];
>> +    struct {
>> +            __u32 isolated:1;
>> +            __u32 reserved:31;
>> +    };
>> +};
>> +
>> +union hv_x64_register_access_info {
>> +    union hv_register_value source_value;
>> +    enum hv_register_name destination_register;
>> +    __u64 source_address;
>> +    __u64 destination_address;
>> +};
>> +
>> +struct hv_x64_register_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    struct {
>> +            __u8 is_memory_op:1;
>> +            __u8 reserved:7;
>> +    };
>> +    __u8 reserved8;
>> +    __u16 reserved16;
>> +    enum hv_register_name register_name;
>> +    union hv_x64_register_access_info access_info;
>> +};
>> +
>> +union hv_x64_memory_access_info {
>> +    __u8 as_uint8;
>> +    struct {
>> +            __u8 gva_valid:1;
>> +            __u8 gva_gpa_valid:1;
>> +            __u8 hypercall_output_pending:1;
>> +            __u8 tlb_locked_no_overlay:1;
>> +            __u8 reserved:4;
>> +    };
>> +};
>> +
>> +union hv_x64_io_port_access_info {
>> +    __u8 as_uint8;
>> +    struct {
>> +            __u8 access_size:3;
>> +            __u8 string_op:1;
>> +            __u8 rep_prefix:1;
>> +            __u8 reserved:3;
>> +    };
>> +};
>> +
>> +union hv_x64_exception_info {
>> +    __u8 as_uint8;
>> +    struct {
>> +            __u8 error_code_valid:1;
>> +            __u8 software_exception:1;
>> +            __u8 reserved:6;
>> +    };
>> +};
>> +
>> +enum hv_cache_type {
>> +    HV_CACHE_TYPE_UNCACHED     = 0,
>> +    HV_CACHE_TYPE_WRITE_COMBINING = 1,
>> +    HV_CACHE_TYPE_WRITE_THROUGH   = 4,
>> +    HV_CACHE_TYPE_WRITE_PROTECTED = 5,
>> +    HV_CACHE_TYPE_WRITE_BACK          = 6
>> +};
>> +
>> +struct hv_x64_memory_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    enum hv_cache_type cache_type;
>> +    __u8 instruction_byte_count;
>> +    union hv_x64_memory_access_info memory_access_info;
>> +    __u8 tpr_priority;
>> +    __u8 reserved1;
>> +    __u64 guest_virtual_address;
>> +    __u64 guest_physical_address;
>> +    __u8 instruction_bytes[16];
>> +};
>> +
>> +struct hv_x64_cpuid_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u64 rax;
>> +    __u64 rcx;
>> +    __u64 rdx;
>> +    __u64 rbx;
>> +    __u64 default_result_rax;
>> +    __u64 default_result_rcx;
>> +    __u64 default_result_rdx;
>> +    __u64 default_result_rbx;
>> +};
>> +
>> +struct hv_x64_msr_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u32 msr_number;
>> +    __u32 reserved;
>> +    __u64 rdx;
>> +    __u64 rax;
>> +};
>> +
>> +struct hv_x64_io_port_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u16 port_number;
>> +    union hv_x64_io_port_access_info access_info;
>> +    __u8 instruction_byte_count;
>> +    __u32 reserved;
>> +    __u64 rax;
>> +    __u8 instruction_bytes[16];
>> +    struct hv_x64_segment_register ds_segment;
>> +    struct hv_x64_segment_register es_segment;
>> +    __u64 rcx;
>> +    __u64 rsi;
>> +    __u64 rdi;
>> +};
>> +
>> +struct hv_x64_exception_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u16 exception_vector;
>> +    union hv_x64_exception_info exception_info;
>> +    __u8 instruction_byte_count;
>> +    __u32 error_code;
>> +    __u64 exception_parameter;
>> +    __u64 reserved;
>> +    __u8 instruction_bytes[16];
>> +    struct hv_x64_segment_register ds_segment;
>> +    struct hv_x64_segment_register ss_segment;
>> +    __u64 rax;
>> +    __u64 rcx;
>> +    __u64 rdx;
>> +    __u64 rbx;
> 
> Is the above the correct ordering (rax, rcd, rdx, rbx)?
> It's just what you would expect ....
> 

This ordering is correct.
Why is it this way? I don't know.

>> +    __u64 rsp;
>> +    __u64 rbp;
>> +    __u64 rsi;
>> +    __u64 rdi;
>> +    __u64 r8;
>> +    __u64 r9;
>> +    __u64 r10;
>> +    __u64 r11;
>> +    __u64 r12;
>> +    __u64 r13;
>> +    __u64 r14;
>> +    __u64 r15;
>> +};
>> +
>> +struct hv_x64_invalid_vp_register_message {
>> +    __u32 vp_index;
>> +    __u32 reserved;
>> +};
>> +
>> +struct hv_x64_unrecoverable_exception_message {
>> +    struct hv_x64_intercept_message_header header;
>> +};
>> +
>> +enum hv_x64_unsupported_feature_code {
>> +    hv_unsupported_feature_intercept = 1,
>> +    hv_unsupported_feature_task_switch_tss = 2
>> +};
>> +
>> +struct hv_x64_unsupported_feature_message {
>> +    __u32 vp_index;
>> +    enum hv_x64_unsupported_feature_code feature_code;
>> +    __u64 feature_parameter;
>> +};
>> +
>> +struct hv_x64_halt_message {
>> +    struct hv_x64_intercept_message_header header;
>> +};
>> +
>> +enum hv_x64_pending_interruption_type {
>> +    HV_X64_PENDING_INTERRUPT        = 0,
>> +    HV_X64_PENDING_NMI              = 2,
>> +    HV_X64_PENDING_EXCEPTION        = 3
>> +};
>> +
>> +struct hv_x64_interruption_deliverable_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    enum hv_x64_pending_interruption_type deliverable_type;
>> +    __u32 rsvd;
>> +};
>> +
>> +struct hv_x64_sipi_intercept_message {
>> +    struct hv_x64_intercept_message_header header;
>> +    __u32 target_vp_index;
>> +    __u32 interrupt_vector;
>> +};
>> +
>> +struct hv_x64_apic_eoi_message {
>> +    __u32 vp_index;
>> +    __u32 interrupt_vector;
>> +};
> 
> Same comments as before about enum types, not depending
> on the compiler to add padding, and marking as __packed.
> 

Yep, will do.

>> +
>>  #endif
>> diff --git a/include/asm-generic/hyperv-tlfs.h 
>> b/include/asm-generic/hyperv-tlfs.h
>> index b9295400c20b..e0185c3872a9 100644
>> --- a/include/asm-generic/hyperv-tlfs.h
>> +++ b/include/asm-generic/hyperv-tlfs.h
>> @@ -241,6 +241,8 @@ static inline const char *hv_status_to_string(enum 
>> hv_status status)
>>  /* Valid SynIC vectors are 16-255. */
>>  #define HV_SYNIC_FIRST_VALID_VECTOR (16)
>>
>> +#define HV_SYNIC_INTERCEPTION_SINT_INDEX 0x00000000
>> +
>>  #define HV_SYNIC_CONTROL_ENABLE             (1ULL << 0)
>>  #define HV_SYNIC_SIMP_ENABLE                (1ULL << 0)
>>  #define HV_SYNIC_SIEFP_ENABLE               (1ULL << 0)
>> @@ -250,49 +252,6 @@ static inline const char *hv_status_to_string(enum 
>> hv_status
>> status)
>>
>>  #define HV_SYNIC_STIMER_COUNT               (4)
>>
>> -/* Define synthetic interrupt controller message constants. */
>> -#define HV_MESSAGE_SIZE                     (256)
>> -#define HV_MESSAGE_PAYLOAD_BYTE_COUNT       (240)
>> -#define HV_MESSAGE_PAYLOAD_QWORD_COUNT      (30)
>> -
>> -/* Define synthetic interrupt controller message flags. */
>> -union hv_message_flags {
>> -    __u8 asu8;
>> -    struct {
>> -            __u8 msg_pending:1;
>> -            __u8 reserved:7;
>> -    } __packed;
>> -};
>> -
>> -/* Define port identifier type. */
>> -union hv_port_id {
>> -    __u32 asu32;
>> -    struct {
>> -            __u32 id:24;
>> -            __u32 reserved:8;
>> -    } __packed u;
>> -};
>> -
>> -/* Define synthetic interrupt controller message header. */
>> -struct hv_message_header {
>> -    __u32 message_type;
>> -    __u8 payload_size;
>> -    union hv_message_flags message_flags;
>> -    __u8 reserved[2];
>> -    union {
>> -            __u64 sender;
>> -            union hv_port_id port;
>> -    };
>> -} __packed;
>> -
>> -/* Define synthetic interrupt controller message format. */
>> -struct hv_message {
>> -    struct hv_message_header header;
>> -    union {
>> -            __u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
>> -    } u;
>> -} __packed;
>> -
>>  /* Define the synthetic interrupt message page layout. */
>>  struct hv_message_page {
>>      struct hv_message sint_message[HV_SYNIC_SINT_COUNT];
>> @@ -306,7 +265,6 @@ struct hv_timer_message_payload {
>>      __u64 delivery_time;    /* When the message was delivered */
>>  } __packed;
>>
>> -
>>  /* Define synthetic interrupt controller flag constants. */
>>  #define HV_EVENT_FLAGS_COUNT                (256 * 8)
>>  #define HV_EVENT_FLAGS_LONG_COUNT   (256 / sizeof(unsigned long))
>> diff --git a/include/linux/mshv.h b/include/linux/mshv.h
>> index dfe469f573f9..7709aaa1e064 100644
>> --- a/include/linux/mshv.h
>> +++ b/include/linux/mshv.h
>> @@ -42,6 +42,7 @@ struct mshv_partition {
>>  };
>>
>>  struct mshv {
>> +    struct hv_message_page __percpu **synic_message_page;
>>      struct {
>>              spinlock_t lock;
>>              u64 count;
>> diff --git a/include/uapi/asm-generic/hyperv-tlfs.h 
>> b/include/uapi/asm-generic/hyperv-
>> tlfs.h
>> index e7b09b9f00de..e87389054b68 100644
>> --- a/include/uapi/asm-generic/hyperv-tlfs.h
>> +++ b/include/uapi/asm-generic/hyperv-tlfs.h
>> @@ -6,6 +6,49 @@
>>  #define BIT(X)      (1ULL << (X))
>>  #endif
>>
>> +/* Define synthetic interrupt controller message constants. */
>> +#define HV_MESSAGE_SIZE                     (256)
>> +#define HV_MESSAGE_PAYLOAD_BYTE_COUNT       (240)
>> +#define HV_MESSAGE_PAYLOAD_QWORD_COUNT      (30)
>> +
>> +/* Define synthetic interrupt controller message flags. */
>> +union hv_message_flags {
>> +    __u8 asu8;
>> +    struct {
>> +            __u8 msg_pending:1;
>> +            __u8 reserved:7;
>> +    };
>> +};
>> +
>> +/* Define port identifier type. */
>> +union hv_port_id {
>> +    __u32 asu32;
>> +    struct {
>> +            __u32 id:24;
>> +            __u32 reserved:8;
>> +    } u;
>> +};
>> +
>> +/* Define synthetic interrupt controller message header. */
>> +struct hv_message_header {
>> +    enum hv_message_type message_type;
>> +    __u8 payload_size;
>> +    union hv_message_flags message_flags;
>> +    __u8 reserved[2];
>> +    union {
>> +            __u64 sender;
>> +            union hv_port_id port;
>> +    };
>> +};
>> +
>> +/* Define synthetic interrupt controller message format. */
>> +struct hv_message {
>> +    struct hv_message_header header;
>> +    union {
>> +            __u64 payload[HV_MESSAGE_PAYLOAD_QWORD_COUNT];
>> +    } u;
>> +};
>> +
>>  /* 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)
>> diff --git a/virt/mshv/mshv_main.c b/virt/mshv/mshv_main.c
>> index 2a10137a1e84..c9445d2edb37 100644
>> --- a/virt/mshv/mshv_main.c
>> +++ b/virt/mshv/mshv_main.c
>> @@ -15,6 +15,8 @@
>>  #include <linux/file.h>
>>  #include <linux/anon_inodes.h>
>>  #include <linux/mm.h>
>> +#include <linux/io.h>
>> +#include <linux/cpuhotplug.h>
>>  #include <linux/mshv.h>
>>  #include <asm/mshyperv.h>
>>
>> @@ -1152,23 +1154,111 @@ mshv_dev_release(struct inode *inode, struct file 
>> *filp)
>>      return 0;
>>  }
>>
>> +static int
>> +mshv_synic_init(unsigned int cpu)
>> +{
>> +    union hv_synic_simp simp;
>> +    union hv_synic_sint sint;
>> +    union hv_synic_scontrol sctrl;
>> +    struct hv_message_page **msg_page =
>> +                    this_cpu_ptr(mshv.synic_message_page);
>> +
>> +    /* Setup the Synic's message page */
>> +    hv_get_simp(simp.as_uint64);
>> +    simp.simp_enabled = true;
>> +    *msg_page = memremap(simp.base_simp_gpa << PAGE_SHIFT,
>> +                         PAGE_SIZE, MEMREMAP_WB);
> 
> Use HV_HYP_PAGE_SHIFT and HV_HYP_PAGE_SIZE.
> 

Yep, will do.

>> +    if (!msg_page) {
>> +            pr_err("%s: memremap failed\n", __func__);
>> +            return -EFAULT;
>> +    }
>> +    hv_set_simp(simp.as_uint64);
>> +
>> +    /* Enable intercepts */
>> +    sint.as_uint64 = 0;
>> +    sint.vector = HYPERVISOR_CALLBACK_VECTOR;
>> +    sint.masked = false;
>> +    sint.auto_eoi = hv_recommend_using_aeoi();
>> +    hv_set_synint_state(HV_SYNIC_INTERCEPTION_SINT_INDEX, sint.as_uint64);
>> +
>> +    /* Enable global synic bit */
>> +    hv_get_synic_state(sctrl.as_uint64);
>> +    sctrl.enable = 1;
>> +    hv_set_synic_state(sctrl.as_uint64);
>> +
>> +    return 0;
>> +}
>> +
>> +static int
>> +mshv_synic_cleanup(unsigned int cpu)
>> +{
>> +    union hv_synic_sint sint;
>> +    union hv_synic_simp simp;
>> +    union hv_synic_scontrol sctrl;
>> +    struct hv_message_page **msg_page =
>> +                    this_cpu_ptr(mshv.synic_message_page);
>> +
>> +    /* Disable the interrupt */
>> +    hv_get_synint_state(HV_SYNIC_INTERCEPTION_SINT_INDEX, sint.as_uint64);
>> +    sint.masked = true;
>> +    hv_set_synint_state(HV_SYNIC_INTERCEPTION_SINT_INDEX, sint.as_uint64);
>> +
>> +    /* Disable Synic's message page */
>> +    hv_get_simp(simp.as_uint64);
>> +    simp.simp_enabled = false;
>> +    hv_set_simp(simp.as_uint64);
>> +    memunmap(*msg_page);
>> +
>> +    /* Disable global synic bit */
>> +    hv_get_synic_state(sctrl.as_uint64);
>> +    sctrl.enable = 0;
>> +    hv_set_synic_state(sctrl.as_uint64);
>> +
>> +    return 0;
>> +}
>> +
>> +static int mshv_cpuhp_online;
>> +
>>  static int
>>  __init mshv_init(void)
>>  {
>> -    int r;
>> +    int ret;
> 
> Ideally, change the name of the variable in the earlier patch so this
> one isn't cluttered with the change.
> 

Will do.

>>
>> -    r = misc_register(&mshv_dev);
>> -    if (r)
>> +    ret = misc_register(&mshv_dev);
>> +    if (ret) {
>>              pr_err("%s: misc device register failed\n", __func__);
>> +            return ret;
>> +    }
>> +    spin_lock_init(&mshv.partitions.lock);
>>
>> +    mshv.synic_message_page = alloc_percpu(struct hv_message_page *);
>> +    if (!mshv.synic_message_page) {
>> +            pr_err("%s: failed to allocate percpu synic page\n", __func__);
>> +            misc_deregister(&mshv_dev);
>> +            return -ENOMEM;
>> +    }
>> +
>> +    ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mshv_synic",
>> +                            mshv_synic_init,
>> +                            mshv_synic_cleanup);
>> +    if (ret < 0) {
>> +            pr_err("%s: failed to setup cpu hotplug state: %i\n",
>> +                   __func__, ret);
>> +            return ret;
>> +    }
>> +
>> +    mshv_cpuhp_online = ret;
>>      spin_lock_init(&mshv.partitions.lock);
> 
> It looks like the spin lock is being initialized twice.
> 

Oops!

>>
>> -    return r;
>> +    return 0;
>>  }
>>
>>  static void
>>  __exit mshv_exit(void)
>>  {
>> +    cpuhp_remove_state(mshv_cpuhp_online);
>> +    free_percpu(mshv.synic_message_page);
>> +
>>      misc_deregister(&mshv_dev);
>>  }
>>
>> --
>> 2.25.1

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