kernel/git/stable/linux.git/drivers/hv/connection.c, branch master

Drivers: hv: Remove support for WS2012/2012R2 & Win8/8.1 version of Hyper-V

2026-08-24T00:35:41+00:00

Linux code for running as a Hyper-V guest includes special cases for running on Hyper-V in WS2012/2012R2 and Windows 8/8.1. These versions were initially released 14 years ago, and official support ended in 2023 (unless a customer has contracted for extended security updates). Given the release of subsequent versions with improved functionality, there's no need to continue to support the latest Linux kernels on these versions of Hyper-V. If someone is running Linux on one of these older Hyper-V versions and doesn't want to upgrade, they can continue to do so as presumably they don't want upgrade the Linux version either. Simplify Linux code by removing special cases for running on these old versions of Hyper-V. Remove the negotiation of the VMBus protocol versions for WS2012/Win8, and remove special case code based on those VMBus protocol versions. Also update the balloon and snapshot drivers to no longer negotiate driver-specific protocol versions for these older Hyper-V versions, and remove any related special cases. Signed-off-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: vmbus: add VTL2 redirect connection ID

2026-07-31T20:02:03+00:00

VMBus sends CHANNELMSG_INITIATE_CONTACT through a Hyper-V message connection ID. Older protocol versions use VMBUS_MESSAGE_CONNECTION_ID, while protocol version 5.0 and newer normally use VMBUS_MESSAGE_CONNECTION_ID_4. For a VTL2 kernel using VMBus protocol 5.0 or newer, the host may expect INITIATE_CONTACT on either the redirect connection ID or VMBUS_MESSAGE_CONNECTION_ID_4. There is no capability indication that identifies which ID is active, so the driver must determine it at runtime. During VMBus negotiation, the redirect ID is tried first because it is used by VTL2 configurations with VMBus redirection enabled. If the redirect ID is unavailable, the host rejects it synchronously with HV_STATUS_INVALID_CONNECTION_ID, allowing fallback to the standard ID. Return a distinct error for an invalid Initiate Contact connection ID so this fallback does not mask other post-message failures or protocol-version rejections. Preserve the existing connection ID selection for older protocol versions or when running below VTL2. Signed-off-by: Hardik Garg Reviewed-by: Tianyu Lan Reviewed-by: Saurabh Sengar Reviewed-by: Naman Jain Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses

2026-02-22T16:26:33+00:00

Conversion performed via this Coccinelle script: // SPDX-License-Identifier: GPL-2.0-only // Options: --include-headers-for-types --all-includes --include-headers --keep-comments virtual patch @gfp depends on patch && !(file in "tools") && !(file in "samples")@ identifier ALLOC = {kmalloc_obj,kmalloc_objs,kmalloc_flex, kzalloc_obj,kzalloc_objs,kzalloc_flex, kvmalloc_obj,kvmalloc_objs,kvmalloc_flex, kvzalloc_obj,kvzalloc_objs,kvzalloc_flex}; @@ ALLOC(... - , GFP_KERNEL ) $ make coccicheck MODE=patch COCCI=gfp.cocci Build and boot tested x86_64 with Fedora 42's GCC and Clang: Linux version 6.19.0+ (user@host) (gcc (GCC) 15.2.1 20260123 (Red Hat 15.2.1-7), GNU ld version 2.44-12.fc42) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Linux version 6.19.0+ (user@host) (clang version 20.1.8 (Fedora 20.1.8-4.fc42), LLD 20.1.8) #1 SMP PREEMPT_DYNAMIC 1970-01-01 Signed-off-by: Kees Cook Signed-off-by: Linus Torvalds

treewide: Replace kmalloc with kmalloc_obj for non-scalar types

2026-02-21T09:02:28+00:00

This is the result of running the Coccinelle script from scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to avoid scalar types (which need careful case-by-case checking), and instead replace kmalloc-family calls that allocate struct or union object instances: Single allocations: kmalloc(sizeof(TYPE), ...) are replaced with: kmalloc_obj(TYPE, ...) Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...) are replaced with: kmalloc_objs(TYPE, COUNT, ...) Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...) are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...) (where TYPE may also be *VAR) The resulting allocations no longer return "void *", instead returning "TYPE *". Signed-off-by: Kees Cook

Drivers: hv: Set the default VMBus version to 6.0

2025-11-15T06:18:15+00:00

The confidential VMBus is supported by the protocol version 6.0 onwards. Attempt to establish the VMBus 6.0 connection thus enabling the confidential VMBus features when available. Signed-off-by: Roman Kisel Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Support confidential VMBus channels

2025-11-15T06:18:15+00:00

To make use of Confidential VMBus channels, initialize the co_ring_buffers and co_external_memory fields of the channel structure. Advertise support upon negotiating the version and compute values for those fields and initialize them. Signed-off-by: Roman Kisel Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Use nested hypercall for post message and signal event

2025-07-15T06:24:16+00:00

When running nested, these hypercalls must be sent to the L0 hypervisor or VMBus will fail. Remove hv_do_nested_hypercall() and hv_do_fast_nested_hypercall8() altogether and open-code these cases, since there are only 2 and all they do is add the nested bit. Signed-off-by: Nuno Das Neves Reviewed-by: Roman Kisel Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1752261532-7225-2-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1752261532-7225-2-git-send-email-nunodasneves@linux.microsoft.com>

Drivers: hv: Allocate interrupt and monitor pages aligned to system page boundary

2025-05-23T16:30:56+00:00

There are use cases that interrupt and monitor pages are mapped to user-mode through UIO, so they need to be system page aligned. Some Hyper-V allocation APIs introduced earlier broke those requirements. Fix this by using page allocation functions directly for interrupt and monitor pages. Cc: stable@vger.kernel.org Fixes: ca48739e59df ("Drivers: hv: vmbus: Move Hyper-V page allocator to arch neutral code") Signed-off-by: Long Li Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1746492997-4599-2-git-send-email-longli@linuxonhyperv.com Signed-off-by: Wei Liu Message-ID: <1746492997-4599-2-git-send-email-longli@linuxonhyperv.com>

Drivers: hv: vmbus: Wait for boot-time offers during boot and resume

2025-01-10T00:54:21+00:00

Channel offers are requested during VMBus initialization and resume from hibernation. Add support to wait for all boot-time channel offers to be delivered and processed before returning from vmbus_request_offers. This is in analogy to a PCI bus not returning from probe until it has scanned all devices on the bus. Without this, user mode can race with VMBus initialization and miss channel offers. User mode has no way to work around this other than sleeping for a while, since there is no way to know when VMBus has finished processing boot-time offers. With this added functionality, remove earlier logic which keeps track of count of offered channels post resume from hibernation. Once all offers delivered message is received, no further boot-time offers are going to be received. Consequently, logic to prevent suspend from happening after previous resume had missing offers, is also removed. Co-developed-by: John Starks Signed-off-by: John Starks Signed-off-by: Naman Jain Reviewed-by: Easwar Hariharan Reviewed-by: Saurabh Sengar Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20250102130712.1661-2-namjain@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250102130712.1661-2-namjain@linux.microsoft.com>

Drivers: hv: vmbus: Leak pages if set_memory_encrypted() fails

2024-04-10T21:33:32+00:00

In CoCo VMs it is possible for the untrusted host to cause set_memory_encrypted() or set_memory_decrypted() to fail such that an error is returned and the resulting memory is shared. Callers need to take care to handle these errors to avoid returning decrypted (shared) memory to the page allocator, which could lead to functional or security issues. VMBus code could free decrypted pages if set_memory_encrypted()/decrypted() fails. Leak the pages if this happens. Signed-off-by: Rick Edgecombe Signed-off-by: Michael Kelley Reviewed-by: Kuppuswamy Sathyanarayanan Acked-by: Kirill A. Shutemov Link: https://lore.kernel.org/r/20240311161558.1310-2-mhklinux@outlook.com Signed-off-by: Wei Liu Message-ID: <20240311161558.1310-2-mhklinux@outlook.com>