kernel/linux.git/drivers/hv/hv_common.c, branch linux-7.1.y

mshv: Handle insufficient root memory hypervisor statuses

2026-02-19T06:42:11+00:00

When creating guest partition objects, the hypervisor may fail to allocate root partition pages and return an insufficient memory status. In this case, deposit memory using the root partition ID instead. Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Reviewed-by: Mukesh R Signed-off-by: Wei Liu

mshv: Handle insufficient contiguous memory hypervisor status

2026-02-19T06:39:16+00:00

The HV_STATUS_INSUFFICIENT_CONTIGUOUS_MEMORY status indicates that the hypervisor lacks sufficient contiguous memory for its internal allocations. When this status is encountered, allocate and deposit HV_MAX_CONTIGUOUS_ALLOCATION_PAGES contiguous pages to the hypervisor. HV_MAX_CONTIGUOUS_ALLOCATION_PAGES is defined in the hypervisor headers, a deposit of this size will always satisfy the hypervisor's requirements. Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Reviewed-by: Mukesh R Signed-off-by: Wei Liu

Drivers: hv: Always do Hyper-V panic notification in hv_kmsg_dump()

2026-01-15T07:01:33+00:00

hv_kmsg_dump() currently skips the panic notification entirely if it doesn't get any message bytes to pass to Hyper-V due to an error from kmsg_dump_get_buffer(). Skipping the notification is undesirable because it leaves the Hyper-V host uncertain about the state of a panic'ed guest. Fix this by always doing the panic notification, even if bytes_written is zero. Also ensure that bytes_written is initialized, which fixes a kernel test robot warning. The warning is actually bogus because kmsg_dump_get_buffer() happens to set bytes_written even if it fails, and in the kernel test robot's CONFIG_PRINTK not set case, hv_kmsg_dump() is never called. But do the initialization for robustness and to quiet the static checker. Fixes: 9c318a1d9b50 ("Drivers: hv: move panic report code from vmbus to hv early init code") Reported-by: kernel test robot Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/202512172103.OcUspn1Z-lkp@intel.com/ Signed-off-by: Michael Kelley Reviewed-by: Roman Kisel Signed-off-by: Wei Liu

Drivers: hv: Use kmalloc_array() instead of kmalloc()

2025-11-15T06:18:17+00:00

Documentation/process/deprecated.rst recommends against the use of kmalloc with dynamic size calculations due to the risk of overflow and smaller allocation being made than the caller was expecting. Replace kmalloc() with kmalloc_array() in hv_common.c to make the intended allocation size clearer and avoid potential overflow issues. The number of pages (pgcount) is bounded, so overflow is not a practical concern here. However, using kmalloc_array() better reflects the intent to allocate an array and improves consistency with other allocations. No functional change intended. Signed-off-by: Rahul Kumar Signed-off-by: Wei Liu

Drivers: hv: Resolve ambiguity in hypervisor version log

2025-11-15T06:18:17+00:00

Update the log message in hv_common_init to explicitly state that the reported version is for the Microsoft Hypervisor, not the host OS. Previously, this message was accurate for guests running on Windows hosts, where the host and hypervisor versions matched. With support for Linux hosts running the Hyper-V hypervisor, the host OS and hypervisor versions may differ. This change avoids confusion by making it clear that the version refers to the Microsoft Hypervisor regardless of the host operating system. Signed-off-by: Stanislav Kinsburskii Reviewed-by: Nuno Das Neves Signed-off-by: Wei Liu

arch/x86: mshyperv: Trap on access for some synthetic MSRs

2025-11-15T06:18:14+00:00

hv_set_non_nested_msr() has special handling for SINT MSRs when a paravisor is present. In addition to updating the MSR on the host, the mirror MSR in the paravisor is updated, including with the proxy bit. But with Confidential VMBus, the proxy bit must not be used, so add a special case to skip it. Signed-off-by: Roman Kisel Reviewed-by: Alok Tiwari Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

arch: hyperv: Get/set SynIC synth.registers via paravisor

2025-11-15T06:18:14+00:00

The existing Hyper-V wrappers for getting and setting MSRs are hv_get/set_msr(). Via hv_get/set_non_nested_msr(), they detect when running in a CoCo VM with a paravisor, and use the TDX or SNP guest-host communication protocol to bypass the paravisor and go directly to the host hypervisor for SynIC MSRs. The "set" function also implements the required special handling for the SINT MSRs. Provide functions that allow manipulating the SynIC registers through the paravisor. Move vmbus_signal_eom() to a more appropriate location (which also avoids breaking KVM). Signed-off-by: Roman Kisel Reviewed-by: Alok Tiwari Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

drivers: hv: Allow vmbus message synic interrupt injected from Hyper-V

2025-11-15T06:18:14+00:00

When Secure AVIC is enabled, VMBus driver should call x2apic Secure AVIC interface to allow Hyper-V to inject VMBus message interrupt. Reviewed-by: Michael Kelley Reviewed-by: Neeraj Upadhyay Signed-off-by: Tianyu Lan Signed-off-by: Wei Liu

mshv: Add support for a new parent partition configuration

2025-09-08T22:10:51+00:00

Detect booting as an "L1VH" partition. This is a new scenario very similar to root partition where the mshv_root driver can be used to create and manage guest partitions. It mostly works the same as root partition, but there are some differences in how various features are handled. hv_l1vh_partition() is introduced to handle these cases. Add hv_parent_partition() which returns true for either case, replacing some hv_root_partition() checks. Signed-off-by: Nuno Das Neves Acked-by: Wei Liu Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Remove hv_alloc/free_* helpers

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

There are no users for those functions, remove them. Signed-off-by: Long Li Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/1746492997-4599-6-git-send-email-longli@linuxonhyperv.com Signed-off-by: Wei Liu Message-ID: <1746492997-4599-6-git-send-email-longli@linuxonhyperv.com>