kernel/linux.git/include/asm-generic/mshyperv.h, branch v6.19.11

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

arch/x86: mshyperv: Discover Confidential VMBus availability

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

Confidential VMBus requires enabling paravisor SynIC, and the x86_64 guest has to inspect the Virtualization Stack (VS) CPUID leaf to see if Confidential VMBus is available. If it is, the guest shall enable the paravisor SynIC. Read the relevant data from the VS CPUID leaf. Refactor the code to avoid repeating CPUID and add flags to the struct ms_hyperv_info. For ARM64, the flag for Confidential VMBus is not set which provides the desired behaviour for now as it is not available on ARM64 just yet. Once ARM64 CCA guests are supported, this flag will be set unconditionally when running such a guest. Signed-off-by: Roman Kisel 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: Fix deposit memory in MSHV_ROOT_HVCALL

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

When the MSHV_ROOT_HVCALL ioctl is executing a hypercall, and gets HV_STATUS_INSUFFICIENT_MEMORY, it deposits memory and then returns -EAGAIN to userspace. The expectation is that the VMM will retry. However, some VMM code in the wild doesn't do this and simply fails. Rather than force the VMM to retry, change the ioctl to deposit memory on demand and immediately retry the hypercall as is done with all the other hypercall helper functions. In addition to making the ioctl easier to use, removing the need for multiple syscalls improves performance. There is a complication: unlike the other hypercall helper functions, in MSHV_ROOT_HVCALL the input is opaque to the kernel. This is problematic for rep hypercalls, because the next part of the input list can't be copied on each loop after depositing pages (this was the original reason for returning -EAGAIN in this case). Introduce hv_do_rep_hypercall_ex(), which adds a 'rep_start' parameter. This solves the issue, allowing the deposit loop in MSHV_ROOT_HVCALL to restart a rep hypercall after depositing pages partway through. Fixes: 621191d709b1 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Nuno Das Neves Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Add CONFIG_HYPERV_VMBUS option

2025-10-01T00:00:42+00:00

At present VMBus driver is hinged off of CONFIG_HYPERV which entails lot of builtin code and encompasses too much. It's not always clear what depends on builtin hv code and what depends on VMBus. Setting CONFIG_HYPERV as a module and fudging the Makefile to switch to builtin adds even more confusion. VMBus is an independent module and should have its own config option. Also, there are scenarios like baremetal dom0/root where support is built in with CONFIG_HYPERV but without VMBus. Lastly, there are more features coming down that use CONFIG_HYPERV and add more dependencies on it. So, create a fine grained HYPERV_VMBUS option and update Kconfigs for dependency on VMBus. Signed-off-by: Mukesh Rathor Acked-by: Bjorn Helgaas # drivers/pci 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>

Drivers: hv: Provide arch-neutral implementation of get_vtl()

2025-05-23T16:30:55+00:00

To run in the VTL mode, Hyper-V drivers have to know what VTL the system boots in, and the arm64/hyperv code does not have the means to compute that. Refactor the code to hoist the function that detects VTL, make it arch-neutral to be able to employ it to get the VTL on arm64. Signed-off-by: Roman Kisel Reviewed-by: Michael Kelley Reviewed-by: Tianyu Lan Link: https://lore.kernel.org/r/20250428210742.435282-5-romank@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <20250428210742.435282-5-romank@linux.microsoft.com>

x86: hyperv: Add mshv_handler() irq handler and setup function

2025-03-20T21:23:04+00:00

Add mshv_handler() to process messages related to managing guest partitions such as intercepts, doorbells, and scheduling messages. In a (non-nested) root partition, the same interrupt vector is shared between the vmbus and mshv_root drivers. Introduce a stub for mshv_handler() and call it in sysvec_hyperv_callback alongside vmbus_handler(). Even though both handlers will be called for every Hyper-V interrupt, the messages for each driver are delivered to different offsets within the SYNIC message page, so they won't step on each other. Signed-off-by: Nuno Das Neves Reviewed-by: Wei Liu Reviewed-by: Tianyu Lan Reviewed-by: Stanislav Kinsburskii Link: https://lore.kernel.org/r/1741980536-3865-9-git-send-email-nunodasneves@linux.microsoft.com Signed-off-by: Wei Liu Message-ID: <1741980536-3865-9-git-send-email-nunodasneves@linux.microsoft.com>