Merge tag 'hyperv-next-signed' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux (6b2591c2) · Commits · 戴 / test

MAINTAINERS

+1 −0

Original line number	Diff line number	Diff line
		@@ -7924,6 +7924,7 @@ F: drivers/pci/controller/pci-hyperv.c
		F: drivers/scsi/storvsc_drv.c
		F: drivers/uio/uio_hv_generic.c
		F: drivers/video/fbdev/hyperv_fb.c
		F: include/asm-generic/hyperv-tlfs.h
		F: include/asm-generic/mshyperv.h
		F: include/clocksource/hyperv_timer.h
		F: include/linux/hyperv.h

arch/x86/include/asm/hyperv-tlfs.h

+36 −436

Original line number	Diff line number	Diff line
		@@ -11,17 +11,6 @@

		#include <linux/types.h>
		#include <asm/page.h>

		/*
		* While not explicitly listed in the TLFS, Hyper-V always runs with a page size
		* of 4096. These definitions are used when communicating with Hyper-V using
		* guest physical pages and guest physical page addresses, since the guest page
		* size may not be 4096 on all architectures.
		*/
		#define HV_HYP_PAGE_SHIFT 12
		#define HV_HYP_PAGE_SIZE BIT(HV_HYP_PAGE_SHIFT)
		#define HV_HYP_PAGE_MASK (~(HV_HYP_PAGE_SIZE - 1))

		/*
		* The below CPUID leaves are present if VersionAndFeatures.HypervisorPresent
		* is set by CPUID(HvCpuIdFunctionVersionAndFeatures).
		@@ -39,78 +28,41 @@
		#define HYPERV_CPUID_MAX 0x4000ffff

		/*
		* Feature identification. EAX indicates which features are available
		* to the partition based upon the current partition privileges.
		* These are HYPERV_CPUID_FEATURES.EAX bits.
		* Aliases for Group A features that have X64 in the name.
		* On x86/x64 these are HYPERV_CPUID_FEATURES.EAX bits.
		*/

		/* VP Runtime (HV_X64_MSR_VP_RUNTIME) available */
		#define HV_X64_MSR_VP_RUNTIME_AVAILABLE BIT(0)
		/* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/
		#define HV_MSR_TIME_REF_COUNT_AVAILABLE BIT(1)
		/*
		* Basic SynIC MSRs (HV_X64_MSR_SCONTROL through HV_X64_MSR_EOM
		* and HV_X64_MSR_SINT0 through HV_X64_MSR_SINT15) available
		*/
		#define HV_X64_MSR_SYNIC_AVAILABLE BIT(2)
		/*
		* Synthetic Timer MSRs (HV_X64_MSR_STIMER0_CONFIG through
		* HV_X64_MSR_STIMER3_COUNT) available
		*/
		#define HV_MSR_SYNTIMER_AVAILABLE BIT(3)
		/*
		* APIC access MSRs (HV_X64_MSR_EOI, HV_X64_MSR_ICR and HV_X64_MSR_TPR)
		* are available
		*/
		#define HV_X64_MSR_APIC_ACCESS_AVAILABLE BIT(4)
		/* Hypercall MSRs (HV_X64_MSR_GUEST_OS_ID and HV_X64_MSR_HYPERCALL) available*/
		#define HV_X64_MSR_HYPERCALL_AVAILABLE BIT(5)
		/* Access virtual processor index MSR (HV_X64_MSR_VP_INDEX) available*/
		#define HV_X64_MSR_VP_INDEX_AVAILABLE BIT(6)
		/* Virtual system reset MSR (HV_X64_MSR_RESET) is available*/
		#define HV_X64_MSR_RESET_AVAILABLE BIT(7)
		/*
		* Access statistics pages MSRs (HV_X64_MSR_STATS_PARTITION_RETAIL_PAGE,
		* HV_X64_MSR_STATS_PARTITION_INTERNAL_PAGE, HV_X64_MSR_STATS_VP_RETAIL_PAGE,
		* HV_X64_MSR_STATS_VP_INTERNAL_PAGE) available
		*/
		#define HV_X64_MSR_STAT_PAGES_AVAILABLE BIT(8)
		/* Partition reference TSC MSR is available */
		#define HV_MSR_REFERENCE_TSC_AVAILABLE BIT(9)
		/* Partition Guest IDLE MSR is available */
		#define HV_X64_MSR_GUEST_IDLE_AVAILABLE BIT(10)
		/*
		* There is a single feature flag that signifies if the partition has access
		* to MSRs with local APIC and TSC frequencies.
		*/
		#define HV_X64_ACCESS_FREQUENCY_MSRS BIT(11)
		/* AccessReenlightenmentControls privilege */
		#define HV_X64_ACCESS_REENLIGHTENMENT BIT(13)
		/* AccessTscInvariantControls privilege */
		#define HV_X64_ACCESS_TSC_INVARIANT BIT(15)
		#define HV_X64_MSR_VP_RUNTIME_AVAILABLE \
		HV_MSR_VP_RUNTIME_AVAILABLE
		#define HV_X64_MSR_SYNIC_AVAILABLE \
		HV_MSR_SYNIC_AVAILABLE
		#define HV_X64_MSR_APIC_ACCESS_AVAILABLE \
		HV_MSR_APIC_ACCESS_AVAILABLE
		#define HV_X64_MSR_HYPERCALL_AVAILABLE \
		HV_MSR_HYPERCALL_AVAILABLE
		#define HV_X64_MSR_VP_INDEX_AVAILABLE \
		HV_MSR_VP_INDEX_AVAILABLE
		#define HV_X64_MSR_RESET_AVAILABLE \
		HV_MSR_RESET_AVAILABLE
		#define HV_X64_MSR_GUEST_IDLE_AVAILABLE \
		HV_MSR_GUEST_IDLE_AVAILABLE
		#define HV_X64_ACCESS_FREQUENCY_MSRS \
		HV_ACCESS_FREQUENCY_MSRS
		#define HV_X64_ACCESS_REENLIGHTENMENT \
		HV_ACCESS_REENLIGHTENMENT
		#define HV_X64_ACCESS_TSC_INVARIANT \
		HV_ACCESS_TSC_INVARIANT

		/*
		* Feature identification: indicates which flags were specified at partition
		* creation. The format is the same as the partition creation flag structure
		* defined in section Partition Creation Flags.
		* These are HYPERV_CPUID_FEATURES.EBX bits.
		* Aliases for Group B features that have X64 in the name.
		* On x86/x64 these are HYPERV_CPUID_FEATURES.EBX bits.
		*/
		#define HV_X64_CREATE_PARTITIONS BIT(0)
		#define HV_X64_ACCESS_PARTITION_ID BIT(1)
		#define HV_X64_ACCESS_MEMORY_POOL BIT(2)
		#define HV_X64_ADJUST_MESSAGE_BUFFERS BIT(3)
		#define HV_X64_POST_MESSAGES BIT(4)
		#define HV_X64_SIGNAL_EVENTS BIT(5)
		#define HV_X64_CREATE_PORT BIT(6)
		#define HV_X64_CONNECT_PORT BIT(7)
		#define HV_X64_ACCESS_STATS BIT(8)
		#define HV_X64_DEBUGGING BIT(11)
		#define HV_X64_CPU_POWER_MANAGEMENT BIT(12)
		#define HV_X64_POST_MESSAGES HV_POST_MESSAGES
		#define HV_X64_SIGNAL_EVENTS HV_SIGNAL_EVENTS

		/*
		* Feature identification. EDX indicates which miscellaneous features
		* are available to the partition.
		* These are HYPERV_CPUID_FEATURES.EDX bits.
		* Group D Features. The bit assignments are custom to each architecture.
		* On x86/x64 these are HYPERV_CPUID_FEATURES.EDX bits.
		*/
		/* The MWAIT instruction is available (per section MONITOR / MWAIT) */
		#define HV_X64_MWAIT_AVAILABLE BIT(0)
		@@ -295,43 +247,6 @@ union hv_x64_msr_hypercall_contents {
		} __packed;
		};

		/*
		* TSC page layout.
		*/
		struct ms_hyperv_tsc_page {
		volatile u32 tsc_sequence;
		u32 reserved1;
		volatile u64 tsc_scale;
		volatile s64 tsc_offset;
		u64 reserved2[509];
		} __packed;

		/*
		* The guest OS needs to register the guest ID with the hypervisor.
		* The guest ID is a 64 bit entity and the structure of this ID is
		* specified in the Hyper-V specification:
		*
		* msdn.microsoft.com/en-us/library/windows/hardware/ff542653%28v=vs.85%29.aspx
		*
		* While the current guideline does not specify how Linux guest ID(s)
		* need to be generated, our plan is to publish the guidelines for
		* Linux and other guest operating systems that currently are hosted
		* on Hyper-V. The implementation here conforms to this yet
		* unpublished guidelines.
		*
		*
		* Bit(s)
		* 63 - Indicates if the OS is Open Source or not; 1 is Open Source
		* 62:56 - Os Type; Linux is 0x100
		* 55:48 - Distro specific identification
		* 47:16 - Linux kernel version number
		* 15:0 - Distro specific identification
		*
		*
		*/

		#define HV_LINUX_VENDOR_ID 0x8100

		struct hv_reenlightenment_control {
		__u64 vector:8;
		__u64 reserved1:8;
		@@ -355,31 +270,12 @@ struct hv_tsc_emulation_status {
		#define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK \
		(~((1ull << HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT) - 1))

		/*
		* Crash notification (HV_X64_MSR_CRASH_CTL) flags.
		*/
		#define HV_CRASH_CTL_CRASH_NOTIFY_MSG BIT_ULL(62)
		#define HV_CRASH_CTL_CRASH_NOTIFY BIT_ULL(63)
		#define HV_X64_MSR_CRASH_PARAMS \
		(1 + (HV_X64_MSR_CRASH_P4 - HV_X64_MSR_CRASH_P0))

		#define HV_IPI_LOW_VECTOR 0x10
		#define HV_IPI_HIGH_VECTOR 0xff

		/* Declare the various hypercall operations. */
		#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE 0x0002
		#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST 0x0003
		#define HVCALL_NOTIFY_LONG_SPIN_WAIT 0x0008
		#define HVCALL_SEND_IPI 0x000b
		#define HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX 0x0013
		#define HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX 0x0014
		#define HVCALL_SEND_IPI_EX 0x0015
		#define HVCALL_POST_MESSAGE 0x005c
		#define HVCALL_SIGNAL_EVENT 0x005d
		#define HVCALL_RETARGET_INTERRUPT 0x007e
		#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_SPACE 0x00af
		#define HVCALL_FLUSH_GUEST_PHYSICAL_ADDRESS_LIST 0x00b0

		#define HV_X64_MSR_VP_ASSIST_PAGE_ENABLE 0x00000001
		#define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT 12
		#define HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_MASK \
		@@ -391,75 +287,6 @@ struct hv_tsc_emulation_status {
		#define HV_X64_MSR_TSC_REFERENCE_ENABLE 0x00000001
		#define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT 12

		#define HV_PROCESSOR_POWER_STATE_C0 0
		#define HV_PROCESSOR_POWER_STATE_C1 1
		#define HV_PROCESSOR_POWER_STATE_C2 2
		#define HV_PROCESSOR_POWER_STATE_C3 3

		#define HV_FLUSH_ALL_PROCESSORS BIT(0)
		#define HV_FLUSH_ALL_VIRTUAL_ADDRESS_SPACES BIT(1)
		#define HV_FLUSH_NON_GLOBAL_MAPPINGS_ONLY BIT(2)
		#define HV_FLUSH_USE_EXTENDED_RANGE_FORMAT BIT(3)

		enum HV_GENERIC_SET_FORMAT {
		HV_GENERIC_SET_SPARSE_4K,
		HV_GENERIC_SET_ALL,
		};

		#define HV_PARTITION_ID_SELF ((u64)-1)

		#define HV_HYPERCALL_RESULT_MASK GENMASK_ULL(15, 0)
		#define HV_HYPERCALL_FAST_BIT BIT(16)
		#define HV_HYPERCALL_VARHEAD_OFFSET 17
		#define HV_HYPERCALL_REP_COMP_OFFSET 32
		#define HV_HYPERCALL_REP_COMP_MASK GENMASK_ULL(43, 32)
		#define HV_HYPERCALL_REP_START_OFFSET 48
		#define HV_HYPERCALL_REP_START_MASK GENMASK_ULL(59, 48)

		/* hypercall status code */
		#define HV_STATUS_SUCCESS 0
		#define HV_STATUS_INVALID_HYPERCALL_CODE 2
		#define HV_STATUS_INVALID_HYPERCALL_INPUT 3
		#define HV_STATUS_INVALID_ALIGNMENT 4
		#define HV_STATUS_INVALID_PARAMETER 5
		#define HV_STATUS_INSUFFICIENT_MEMORY 11
		#define HV_STATUS_INVALID_PORT_ID 17
		#define HV_STATUS_INVALID_CONNECTION_ID 18
		#define HV_STATUS_INSUFFICIENT_BUFFERS 19

		/*
		* The Hyper-V TimeRefCount register and the TSC
		* page provide a guest VM clock with 100ns tick rate
		*/
		#define HV_CLOCK_HZ (NSEC_PER_SEC/100)

		typedef struct _HV_REFERENCE_TSC_PAGE {
		__u32 tsc_sequence;
		__u32 res1;
		__u64 tsc_scale;
		__s64 tsc_offset;
		} __packed HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;

		/* Define the number of synthetic interrupt sources. */
		#define HV_SYNIC_SINT_COUNT (16)
		/* Define the expected SynIC version. */
		#define HV_SYNIC_VERSION_1 (0x1)
		/* Valid SynIC vectors are 16-255. */
		#define HV_SYNIC_FIRST_VALID_VECTOR (16)

		#define HV_SYNIC_CONTROL_ENABLE (1ULL << 0)
		#define HV_SYNIC_SIMP_ENABLE (1ULL << 0)
		#define HV_SYNIC_SIEFP_ENABLE (1ULL << 0)
		#define HV_SYNIC_SINT_MASKED (1ULL << 16)
		#define HV_SYNIC_SINT_AUTO_EOI (1ULL << 17)
		#define HV_SYNIC_SINT_VECTOR_MASK (0xFF)

		#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 hypervisor message types. */
		enum hv_message_type {
		@@ -489,57 +316,6 @@ enum hv_message_type {
		HVMSG_X64_LEGACY_FP_ERROR = 0x80010005
		};

		/* 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];
		} __packed;

		/* Define timer message payload structure. */
		struct hv_timer_message_payload {
		__u32 timer_index;
		__u32 reserved;
		__u64 expiration_time; /* When the timer expired */
		__u64 delivery_time; /* When the message was delivered */
		} __packed;

		struct hv_nested_enlightenments_control {
		struct {
		__u32 directhypercall:1;
		@@ -767,187 +543,11 @@ struct hv_enlightened_vmcs {

		#define HV_VMX_ENLIGHTENED_CLEAN_FIELD_ALL 0xFFFF

		/* Define synthetic interrupt controller flag constants. */
		#define HV_EVENT_FLAGS_COUNT (256 * 8)
		#define HV_EVENT_FLAGS_LONG_COUNT (256 / sizeof(unsigned long))

		/*
		* Synthetic timer configuration.
		*/
		union hv_stimer_config {
		u64 as_uint64;
		struct {
		u64 enable:1;
		u64 periodic:1;
		u64 lazy:1;
		u64 auto_enable:1;
		u64 apic_vector:8;
		u64 direct_mode:1;
		u64 reserved_z0:3;
		u64 sintx:4;
		u64 reserved_z1:44;
		} __packed;
		};


		/* Define the synthetic interrupt controller event flags format. */
		union hv_synic_event_flags {
		unsigned long flags[HV_EVENT_FLAGS_LONG_COUNT];
		};

		/* Define SynIC control register. */
		union hv_synic_scontrol {
		u64 as_uint64;
		struct {
		u64 enable:1;
		u64 reserved:63;
		} __packed;
		};

		/* Define synthetic interrupt source. */
		union hv_synic_sint {
		u64 as_uint64;
		struct {
		u64 vector:8;
		u64 reserved1:8;
		u64 masked:1;
		u64 auto_eoi:1;
		u64 polling:1;
		u64 reserved2:45;
		} __packed;
		};

		/* Define the format of the SIMP register */
		union hv_synic_simp {
		u64 as_uint64;
		struct {
		u64 simp_enabled:1;
		u64 preserved:11;
		u64 base_simp_gpa:52;
		} __packed;
		};

		/* Define the format of the SIEFP register */
		union hv_synic_siefp {
		u64 as_uint64;
		struct {
		u64 siefp_enabled:1;
		u64 preserved:11;
		u64 base_siefp_gpa:52;
		} __packed;
		};

		struct hv_vpset {
		u64 format;
		u64 valid_bank_mask;
		u64 bank_contents[];
		} __packed;

		/* HvCallSendSyntheticClusterIpi hypercall */
		struct hv_send_ipi {
		u32 vector;
		u32 reserved;
		u64 cpu_mask;
		} __packed;

		/* HvCallSendSyntheticClusterIpiEx hypercall */
		struct hv_send_ipi_ex {
		u32 vector;
		u32 reserved;
		struct hv_vpset vp_set;
		} __packed;

		/* HvFlushGuestPhysicalAddressSpace hypercalls */
		struct hv_guest_mapping_flush {
		u64 address_space;
		u64 flags;
		} __packed;

		/*
		* HV_MAX_FLUSH_PAGES = "additional_pages" + 1. It's limited
		* by the bitwidth of "additional_pages" in union hv_gpa_page_range.
		*/
		#define HV_MAX_FLUSH_PAGES (2048)

		/* HvFlushGuestPhysicalAddressList hypercall */
		union hv_gpa_page_range {
		u64 address_space;
		struct {
		u64 additional_pages:11;
		u64 largepage:1;
		u64 basepfn:52;
		} page;
		};

		/*
		* All input flush parameters should be in single page. The max flush
		* count is equal with how many entries of union hv_gpa_page_range can
		* be populated into the input parameter page.
		*/
		#define HV_MAX_FLUSH_REP_COUNT ((HV_HYP_PAGE_SIZE - 2 * sizeof(u64)) / \
		sizeof(union hv_gpa_page_range))

		struct hv_guest_mapping_flush_list {
		u64 address_space;
		u64 flags;
		union hv_gpa_page_range gpa_list[HV_MAX_FLUSH_REP_COUNT];
		};

		/* HvFlushVirtualAddressSpace, HvFlushVirtualAddressList hypercalls */
		struct hv_tlb_flush {
		u64 address_space;
		u64 flags;
		u64 processor_mask;
		u64 gva_list[];
		} __packed;

		/* HvFlushVirtualAddressSpaceEx, HvFlushVirtualAddressListEx hypercalls */
		struct hv_tlb_flush_ex {
		u64 address_space;
		u64 flags;
		struct hv_vpset hv_vp_set;
		u64 gva_list[];
		} __packed;

		struct hv_partition_assist_pg {
		u32 tlb_lock_count;
		};

		union hv_msi_entry {
		u64 as_uint64;
		struct {
		u32 address;
		u32 data;
		} __packed;
		};

		struct hv_interrupt_entry {
		u32 source; /* 1 for MSI(-X) */
		u32 reserved1;
		union hv_msi_entry msi_entry;
		} __packed;

		/*
		* flags for hv_device_interrupt_target.flags
		*/
		#define HV_DEVICE_INTERRUPT_TARGET_MULTICAST 1
		#define HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET 2

		struct hv_device_interrupt_target {
		u32 vector;
		u32 flags;
		union {
		u64 vp_mask;
		struct hv_vpset vp_set;
		};
		} __packed;
		#include <asm-generic/hyperv-tlfs.h>

		/* HvRetargetDeviceInterrupt hypercall */
		struct hv_retarget_device_interrupt {
		u64 partition_id; /* use "self" */
		u64 device_id;
		struct hv_interrupt_entry int_entry;
		u64 reserved2;
		struct hv_device_interrupt_target int_target;
		} __packed __aligned(8);
		#endif

arch/x86/include/asm/kvm_host.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -866,7 +866,7 @@ struct kvm_hv {
		u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
		u64 hv_crash_ctl;

		HV_REFERENCE_TSC_PAGE tsc_ref;
		struct ms_hyperv_tsc_page tsc_ref;

		struct idr conn_to_evt;

arch/x86/kvm/hyperv.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -900,7 +900,7 @@ static int kvm_hv_msr_set_crash_data(struct kvm_vcpu *vcpu,
		* These two equivalencies are implemented in this function.
		*/
		static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info *hv_clock,
		HV_REFERENCE_TSC_PAGE *tsc_ref)
		struct ms_hyperv_tsc_page *tsc_ref)
		{
		u64 max_mul;

		@@ -941,7 +941,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
		u64 gfn;

		BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv->tsc_ref.tsc_sequence));
		BUILD_BUG_ON(offsetof(HV_REFERENCE_TSC_PAGE, tsc_sequence) != 0);
		BUILD_BUG_ON(offsetof(struct ms_hyperv_tsc_page, tsc_sequence) != 0);

		if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
		return;

drivers/hv/channel.c

+41 −17

Original line number	Diff line number	Diff line
		@@ -289,6 +289,34 @@ int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
		}
		EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);

		/*
		* Set/change the vCPU (@target_vp) the channel (@child_relid) will interrupt.
		*
		* CHANNELMSG_MODIFYCHANNEL messages are aynchronous. Also, Hyper-V does not
		* ACK such messages. IOW we can't know when the host will stop interrupting
		* the "old" vCPU and start interrupting the "new" vCPU for the given channel.
		*
		* The CHANNELMSG_MODIFYCHANNEL message type is supported since VMBus version
		* VERSION_WIN10_V4_1.
		*/
		int vmbus_send_modifychannel(u32 child_relid, u32 target_vp)
		{
		struct vmbus_channel_modifychannel conn_msg;
		int ret;

		memset(&conn_msg, 0, sizeof(conn_msg));
		conn_msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
		conn_msg.child_relid = child_relid;
		conn_msg.target_vp = target_vp;

		ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);

		trace_vmbus_send_modifychannel(&conn_msg, ret);

		return ret;
		}
		EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);

		/*
		* create_gpadl_header - Creates a gpadl for the specified buffer
		*/
		@@ -594,35 +622,31 @@ post_msg_err:
		}
		EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);

		static void reset_channel_cb(void *arg)
		{
		struct vmbus_channel *channel = arg;

		channel->onchannel_callback = NULL;
		}

		void vmbus_reset_channel_cb(struct vmbus_channel *channel)
		{
		unsigned long flags;

		/*
		* vmbus_on_event(), running in the per-channel tasklet, can race
		* with vmbus_close_internal() in the case of SMP guest, e.g., when
		* the former is accessing channel->inbound.ring_buffer, the latter
		* could be freeing the ring_buffer pages, so here we must stop it
		* first.
		*
		* vmbus_chan_sched() might call the netvsc driver callback function
		* that ends up scheduling NAPI work that accesses the ring buffer.
		* At this point, we have to ensure that any such work is completed
		* and that the channel ring buffer is no longer being accessed, cf.
		* the calls to napi_disable() in netvsc_device_remove().
		*/
		tasklet_disable(&channel->callback_event);

		channel->sc_creation_callback = NULL;
		/* See the inline comments in vmbus_chan_sched(). */
		spin_lock_irqsave(&channel->sched_lock, flags);
		channel->onchannel_callback = NULL;
		spin_unlock_irqrestore(&channel->sched_lock, flags);

		/* Stop the callback asap */
		if (channel->target_cpu != get_cpu()) {
		put_cpu();
		smp_call_function_single(channel->target_cpu, reset_channel_cb,
		channel, true);
		} else {
		reset_channel_cb(channel);
		put_cpu();
		}
		channel->sc_creation_callback = NULL;

		/* Re-enable tasklet for use on re-open */
		tasklet_enable(&channel->callback_event);

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