kernel/linux.git/drivers/hv/hv.c, branch v7.1

mshv: limit SynIC management to MSHV-owned resources

2026-04-29T22:56:53+00:00

The SynIC is shared between VMBus and MSHV. VMBus owns the message page (SIMP), event flags page (SIEFP), global enable (SCONTROL), and SINT2. MSHV adds SINT0, SINT5, and the event ring page (SIRBP). Currently mshv_synic_cpu_init() redundantly enables SIMP, SIEFP, and SCONTROL that VMBus already configured, and mshv_synic_cpu_exit() disables all of them. This is wrong because MSHV can be torn down while VMBus is still active. In particular, a kexec reboot notifier tears down MSHV first. Disabling SCONTROL, SIMP, and SIEFP out from under VMBus causes its later cleanup to write SynIC MSRs while SynIC is disabled, which the hypervisor does not tolerate. Restrict MSHV to managing only the resources it owns: - SINT0, SINT5: mask on cleanup, unmask on init - SIRBP: enable/disable as before - SIMP, SIEFP, SCONTROL: leave to VMBus when it is active (L1VH and nested root partition); on a non-nested root partition VMBus does not run, so MSHV must enable/disable them While here, fix the SIEFP and SIRBP memremap() and virt_to_phys() calls to use HV_HYP_PAGE_SHIFT/HV_HYP_PAGE_SIZE instead of PAGE_SHIFT/PAGE_SIZE. The hypervisor always uses 4K pages for SynIC register GPAs regardless of the kernel page size, so using PAGE_SHIFT produces wrong addresses on ARM64 with 64K pages. Note that initialization order matters - VMBUS first, MSHV second, and the reverse on de-init. Ideally, we would want a dedicated SYNIC driver that replaces the cross-dependencies with a clear API and dynamic tracking. Such refactor should go into its own dedicated series, outside of this kexec fix series. Signed-off-by: Jork Loeser Reviewed-by: Anirudh Rayabharam (Microsoft) Reviewed-by: Stanislav Kinsburskii Signed-off-by: Wei Liu

Convert more 'alloc_obj' cases to default GFP_KERNEL arguments

2026-02-22T04:03:00+00:00

This converts some of the visually simpler cases that have been split over multiple lines. I only did the ones that are easy to verify the resulting diff by having just that final GFP_KERNEL argument on the next line. Somebody should probably do a proper coccinelle script for this, but for me the trivial script actually resulted in an assertion failure in the middle of the script. I probably had made it a bit _too_ trivial. So after fighting that far a while I decided to just do some of the syntactically simpler cases with variations of the previous 'sed' scripts. The more syntactically complex multi-line cases would mostly really want whitespace cleanup anyway. 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: Use memremap()/memunmap() instead of ioremap_cache()/iounmap()

2026-02-04T06:29:12+00:00

When running with a paravisor or in the root partition, the SynIC event and message pages are provided by the paravisor or hypervisor respectively, instead of being allocated by Linux. The provided pages are normal memory, but are outside of the physical address space seen by Linux. As such they cannot be accessed via the kernel's direct map, and must be explicitly mapped to a kernel virtual address. Current code uses ioremap_cache() and iounmap() to map and unmap the pages. These functions are for use on I/O address space that may not behave as normal memory, so they generate or expect addresses with the __iomem attribute. For normal memory, the preferred functions are memremap() and memunmap(), which operate similarly but without __iomem. At the time of the original work on CoCo VMs on Hyper-V, memremap() did not support creating a decrypted mapping, so ioremap_cache() was used instead, since I/O address space is always mapped decrypted. memremap() has since been enhanced to allow decrypted mappings, so replace ioremap_cache() with memremap() when mapping the event and message pages. Similarly, replace iounmap() with memunmap(). As a side benefit, the replacement cleans up 'sparse' warnings about __iomem mismatches. The replacement is done to use the correct functions as long-term goodness and to clean up the sparse warnings. No runtime bugs are fixed. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202601170445.JtZQwndW-lkp@intel.com/ Closes: https://lore.kernel.org/oe-kbuild-all/202512150359.fMdmbddk-lkp@intel.com/ Signed-off-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Export some symbols for mshv_vtl

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

MSHV_VTL driver is going to be introduced, which is supposed to provide interface for Virtual Machine Monitors (VMMs) to control Virtual Trust Level (VTL). Export the symbols needed to make it work (vmbus_isr, hv_context and hv_post_message). Co-developed-by: Roman Kisel Signed-off-by: Roman Kisel Co-developed-by: Saurabh Sengar Signed-off-by: Saurabh Sengar Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202506110544.q0NDMQVc-lkp@intel.com/ Reviewed-by: Michael Kelley Signed-off-by: Naman Jain Signed-off-by: Wei Liu

Drivers: hv: Functions for setting up and tearing down the paravisor SynIC

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

The confidential VMBus runs with the paravisor SynIC and requires configuring it with the paravisor. Add the functions for configuring the paravisor SynIC. Update overall SynIC initialization logic to initialize the SynIC if it is present. Finally, break out SynIC interrupt enable/disable code into separate functions so that SynIC interrupts can be enabled or disabled via the paravisor instead of the hypervisor if the paravisor SynIC is present. Signed-off-by: Roman Kisel Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Rename the SynIC enable and disable routines

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

The confidential VMBus requires support for the both hypervisor facing SynIC and the paravisor one. Rename the functions that enable and disable SynIC with the hypervisor. No functional changes. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Check message and event pages for non-NULL before iounmap()

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

It might happen that some hyp SynIC pages aren't allocated. Check for that and only then call iounmap(). Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: remove stale comment

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

The comment about the x2v shim is ancient and long since incorrect. Remove the incorrect comment. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu

Drivers: hv: Post messages through the confidential VMBus if available

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

When the confidential VMBus is available, the guest should post messages to the paravisor. Update hv_post_message() to post messages to the paravisor rather than through GHCB or TD calls. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu