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Drivers: hv: vmbus: add VTL2 redirect connection ID #162

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Merged
Hardik Garg (hargar19) merged 3 commits into from
Oct 14, 2026
Merged

Drivers: hv: vmbus: add VTL2 redirect connection ID #162

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1fad9da
Revert "Drivers: hv: Add connection id support"
hargar19 Oct 8, 2026
6b4692f
Drivers: hv: vmbus: add VTL2 redirect connection ID
hargar19 Jul 17, 2026
9f7a9d9
MSFT-Merge: retire superseded connection ID patch
hargar19 Oct 8, 2026
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13 changes: 11 additions & 2 deletions MSFT-Merge/commit-log
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Original file line number Diff line number Diff line change
Expand Up @@ -119,7 +119,6 @@ c630cc37901b 2026-08-14 x86/apic/savic: get GPA for SAVIC page using per_cpu_
Patch series in progress
------------------------
6fd11a76911a 2024-04-17 PCI: Add a mutex to protect the global list pci_domain_busn_res_list (Status: Sent V1; Approx LOC: 25; Reference: https://lore.kernel.org/lkml/20240419015302.13871-1-decui@microsoft.com/; Testing: Tested on AH24) [Dexuan]
995392d1b714 2024-01-22 Drivers: hv: Add connection id support (Status: In review; Approx LOC: 8; Testing: Tested on AH27) [Hardik]
31a427ddeaf1 2025-02-11 vfio/pci: Continue to refactor vfio_pci_core_do_io_rw (Status: In review; Approx LOC: 30; Reference: https://lore.kernel.org/all/20240425165604.899447-4-gbayer@linux.ibm.com/) [Gerd Bayer (IBM)]
3dcb6050cf8b 2024-05-17 drivers/vmbus: Enhance Interrupt Management (Status: In review; Approx LOC: 850; Reference: [PATCH v2 00/15] Add arm64 support in MSHV_VTL - Naman Jain) [Naman]
e3d9aa18101a 2024-05-17 drivers/hv: Enable MSHV_VTL_MODE for arm64 [-]
Expand All @@ -131,4 +130,14 @@ f1bc8fdb27b1 2025-12-04 Fix x86 compilation errors [-]
1ada4de76a9f 2026-02-26 vtl: Fixes for compilation errors and warnings [-]
cff21e6cb023 2025-04-22 hv: mshv: vtl: Allow aarch64 to use the Hyper-V VTL register page when available. (#53) [-]
f701d02a32b1 2024-06-05 hyperv/arm64: Use PSCI to start processors. [-]
f6c55e5bec93 2023-02-16 x86/build: Only align ENTRY_TEXT to PMD_SIZE on x86 if PTI or SRSO is enabled. (Status: In review v4; Approx LOC: 10) [Hamza]
f6c55e5bec93 2023-02-16 x86/build: Only align ENTRY_TEXT to PMD_SIZE on x86 if PTI or SRSO is enabled. (Status: In review v4; Approx LOC: 10) [Hamza]


Retired / superseded OOT commits
--------------------------------
995392d1b714 2024-01-22 Drivers: hv: Add connection id support [Hardik]
Status: RETIRED - superseded by upstream
Revert: 1fad9da94612
Replacement: ceb19f46e475 (6.18 stable); 92d059312802 (mainline)
Upgrade policy: Never replay the original or its revert.
Backport the replacement only if the target base lacks an equivalent fix.
60 changes: 28 additions & 32 deletions drivers/hv/connection.c
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Expand Up @@ -71,17 +71,8 @@ module_param(max_version, uint, S_IRUGO);
MODULE_PARM_DESC(max_version,
"Maximal VMBus protocol version which can be negotiated");

/*
* User requested connection id used to connect to the host. Useful for testing
* or when running a vmbus server on a non-standard connection id.
*/
static uint message_connection_id;

module_param(message_connection_id, uint, 0444);
MODULE_PARM_DESC(message_connection_id,
"The VMBus message connection id used to communicate with the Host");

int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
static int vmbus_try_connection_id(struct vmbus_channel_msginfo *msginfo,
u32 version, u32 connection_id)
{
int ret = 0;
struct vmbus_channel_initiate_contact *msg;
Expand All @@ -96,28 +87,25 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
msg->vmbus_version_requested = version;

/*
* VMBus protocol 5.0 (VERSION_WIN10_V5) and higher require that we must
* use VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate Contact Message,
* and for subsequent messages, we must use the Message Connection ID
* field in the host-returned Version Response Message. And, with
* VERSION_WIN10_V5 and higher, we don't use msg->interrupt_page, but we
* tell the host explicitly that we still use VMBUS_MESSAGE_SINT(2) for
* compatibility.
* For VMBus protocol 5.0 (VERSION_WIN10_V5) and higher, use the
* caller-supplied connection_id for the Initiate Contact message so
* the caller can implement the required retry scheme. For subsequent
* messages, use the Message Connection ID field in the host-returned
* Version Response message. With VERSION_WIN10_V5 and higher, we don't
* use msg->interrupt_page, but tell the host explicitly that we still
* use VMBUS_MESSAGE_SINT(2) for compatibility.
*
* On old hosts, we should always use VMBUS_MESSAGE_CONNECTION_ID (1).
*/
if (version >= VERSION_WIN10_V5) {
msg->msg_sint = VMBUS_MESSAGE_SINT;
msg->msg_vtl = ms_hyperv.vtl;
vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID_4;
vmbus_connection.msg_conn_id = connection_id;
} else {
msg->interrupt_page = virt_to_phys(vmbus_connection.int_page);
vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
}

if (message_connection_id > 0)
vmbus_connection.msg_conn_id = message_connection_id;

/*
* shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
* bitwise OR it
Expand Down Expand Up @@ -174,6 +162,22 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
return ret;
}

int vmbus_negotiate_version(struct vmbus_channel_msginfo *msginfo, u32 version)
{
int ret;

/* Try the redirect ID first for VTL2 with VMBus protocol 5.0+. */
if (version >= VERSION_WIN10_V5 && ms_hyperv.vtl == 2) {
ret = vmbus_try_connection_id(msginfo, version,
VMBUS_MESSAGE_CONNECTION_ID_REDIRECT);
if (ret != -ENXIO)
return ret;
}

return vmbus_try_connection_id(msginfo, version,
VMBUS_MESSAGE_CONNECTION_ID_4);
}

/*
* vmbus_connect - Sends a connect request on the partition service connection
*/
Expand Down Expand Up @@ -467,18 +471,10 @@ int vmbus_post_msg(void *buffer, size_t buflen, bool can_sleep)

switch (ret) {
case HV_STATUS_INVALID_CONNECTION_ID:
/*
* See vmbus_negotiate_version(): VMBus protocol 5.0
* and higher require that we must use
* VMBUS_MESSAGE_CONNECTION_ID_4 for the Initiate
* Contact message, but on old hosts that only
* support VMBus protocol 4.0 or lower, here we get
* HV_STATUS_INVALID_CONNECTION_ID and we should
* return an error immediately without retrying.
*/
/* Allow INITIATE_CONTACT to try another connection ID. */
hdr = buffer;
if (hdr->msgtype == CHANNELMSG_INITIATE_CONTACT)
return -EINVAL;
return -ENXIO;
/*
* We could get this if we send messages too
* frequently.
Expand Down
2 changes: 2 additions & 0 deletions drivers/hv/hyperv_vmbus.h
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Expand Up @@ -109,6 +109,8 @@ struct hv_input_post_message {
enum {
VMBUS_MESSAGE_CONNECTION_ID = 1,
VMBUS_MESSAGE_CONNECTION_ID_4 = 4,
/* VTL2 redirect connection ID for INITIATE_CONTACT. */
VMBUS_MESSAGE_CONNECTION_ID_REDIRECT = 0x800074,
VMBUS_MESSAGE_PORT_ID = 1,
VMBUS_EVENT_CONNECTION_ID = 2,
VMBUS_EVENT_PORT_ID = 2,
Expand Down
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