kernel/linux.git/drivers/hv, branch v6.18.48

mshv: Order pt_vp_array publish against irqfd assertion path

2026-08-09T18:25:10+00:00

[ Upstream commit b098dc869219c15dc49bf9cf63fb5fc1481d3373 ] mshv_partition_ioctl_create_vp() initialises a VP struct (allocations, mutex_init, init_waitqueue_head, page mappings) and then publishes the pointer into partition->pt_vp_array. Several ISR paths read this array locklessly: the intercept ISR, the two scheduler ISRs, and mshv_try_assert_irq_fast() on the irqfd fast path. Of these, only mshv_try_assert_irq_fast() can structurally race the publish. It runs from an eventfd waker without holding pt_mutex, and MSHV_IRQFD does not require the target lapic_apic_id (== vp_index) to refer to an existing VP at registration time. A user can therefore register an irqfd targeting a yet-to-be-created VP, then trigger mshv_try_assert_irq_fast() concurrently with MSHV_CREATE_VP for the same index. On weakly-ordered architectures the reader can observe a non-NULL pointer in pt_vp_array before the initialising stores to the VP struct become visible, leading to use of partially-initialised fields (e.g. vp_register_page). The other ISR readers cannot reach this race: the hypervisor will not generate intercept or scheduler messages for a VP that has never been told to run, and the user can only call MSHV_RUN_VP on the VP fd returned by MSHV_CREATE_VP, which by construction is returned after the publish. Leave those readers as plain loads. Use smp_store_release() in mshv_partition_ioctl_create_vp() to publish the pointer, and pair it with smp_load_acquire() in mshv_try_assert_irq_fast(). On x86 these compile to plain accesses under TSO; on ARM64 they emit one-instruction acquire/release barriers, acceptable on this fast path. The destroy-side path (destroy_partition() clearing pt_vp_array[i] to NULL after kfree(vp)) has a separate ordering and lifetime concern that is out of scope here. Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

mshv: Fix level-triggered check on uninitialized data

2026-08-09T18:25:10+00:00

[ Upstream commit 0289a67cd70bf9d3807e289f4efd643e16a6c6b4 ] In mshv_irqfd_assign(), the level-triggered validation for resample irqfds checks irqfd_lapic_irq.lapic_control.level_triggered before mshv_irqfd_update() has populated the field. Since the irqfd struct is zero-allocated, level_triggered is always 0 at that point, causing the check to always reject resample irqfds with -EINVAL. This makes level-triggered interrupt resampling — used to avoid interrupt storms with assigned devices — completely non-functional. Move the check after the mshv_irqfd_update() call, which resolves the IRQ routing entry and populates irqfd_lapic_irq with the actual trigger mode. Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

mshv: adjust interrupt control structure for ARM64

2026-08-09T18:25:10+00:00

[ Upstream commit 9d70ef7a18e0ec1653ac63020a13a5d4dda7cc0d ] Interrupt control structure (union hv_interupt_control) has different fields when it comes to x86 vs ARM64. Bring in the correct structure from HyperV header files and adjust the existing interrupt routing code accordingly. Signed-off-by: Jinank Jain Signed-off-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Stable-dep-of: 0289a67cd70b ("mshv: Fix level-triggered check on uninitialized data") Signed-off-by: Sasha Levin

mshv: Fix race in mshv_irqfd_deassign

2026-08-09T18:25:10+00:00

[ Upstream commit 0762262ac3e70f65b3bb843fe892f8bac1562d08 ] mshv_irqfd_deactivate() and the hlist traversal of pt_irqfds_list require pt->pt_irqfds_lock to be held, but mshv_irqfd_deassign() omits it. This races with the EPOLLHUP path in mshv_irqfd_wakeup(), which does take the lock before calling mshv_irqfd_deactivate(). Additionally, mshv_irqfd_deactivate() uses hlist_del() which poisons the node pointers rather than resetting them. Since mshv_irqfd_is_active() relies on hlist_unhashed() (checks pprev == NULL), a poisoned node still appears active. If a concurrent path calls mshv_irqfd_deactivate() again on the same irqfd, the guard fails to prevent a double hlist_del() on poisoned pointers. Fix both issues: - Add the missing spin_lock_irq/spin_unlock_irq around the list traversal in mshv_irqfd_deassign(), matching mshv_irqfd_release(). - Use hlist_del_init() instead of hlist_del() so the node is properly marked as unhashed after removal, making the is_active guard reliable. Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

mshv: Fix sleeping under spinlock in mshv_portid_alloc

2026-08-09T18:25:00+00:00

[ Upstream commit a9708e550d11a53b22d932cdbfaa10c26346a2d0 ] idr_alloc() is called with GFP_KERNEL inside idr_lock(), which holds a spinlock. GFP_KERNEL allows the allocator to sleep, triggering a sleeping-while-atomic bug. Fix by using idr_preload(GFP_KERNEL) before taking the lock to pre-allocate memory in a sleepable context, then idr_alloc() with GFP_NOWAIT inside the spinlock-protected section. Fixes: 621191d709b1 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

mshv: Fix duplicate GSI detection for GSI 0

2026-08-09T18:25:00+00:00

[ Upstream commit 649dd135491945afa544351e3e6d4a727de87020 ] The duplicate routing entry check in mshv_update_routing_table() uses guest_irq_num != 0 to detect whether a GSI slot is already occupied. This fails for GSI 0 because its guest_irq_num is 0 both when the slot is unused (zero-initialized) and when legitimately assigned. As a result, duplicate entries for GSI 0 are silently accepted, with the second entry overwriting the first — corrupting the routing table without any error reported to userspace. While GSI 0 (legacy timer) is unlikely to appear in MSI-based routing in practice, the check is semantically wrong — it conflates "uninitialized" with "GSI number 0." Use girq_entry_valid instead, which is explicitly set to true when an entry is populated and remains zero for unused slots regardless of the GSI number. Fixes: 621191d709b14 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Signed-off-by: Stanislav Kinsburskii Reviewed-by: Anirudh Rayabharam (Microsoft) Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

Drivers: hv: vmbus: Replace lockdep_hardirq_threaded() with lockdep annotation

2026-08-09T18:25:00+00:00

[ Upstream commit 8c7ab779c8850f4dab8473463cca9a7d52fdaecc ] lockdep_hardirq_threaded() is supposed to be used within IRQ core code and not within drivers. It is not obvious from within the driver, that this is the only interrupt service routing and that it is not shared handler. Replace lockdep_hardirq_threaded() with a lockdep annotation limiting threaded context on PREEMPT_RT to __vmbus_isr(). Fixes: f8e6343b7a89c ("Drivers: hv: vmbus: Use kthread for vmbus interrupts on PREEMPT_RT") Signed-off-by: Sebastian Andrzej Siewior Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Signed-off-by: Sasha Levin

Drivers: hv: Allocate the paravisor SynIC pages when required

2026-08-09T18:25:00+00:00

[ Upstream commit 226494e5ee4eb0bae4fc7b525505828271d5047e ] Confidential VMBus requires interacting with two SynICs -- one provided by the host hypervisor, and one provided by the paravisor. Each SynIC requires its own message and event pages. Refactor and extend the existing code to add allocating and freeing the message and event pages for the paravisor SynIC when it is present. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Stable-dep-of: 8c7ab779c885 ("Drivers: hv: vmbus: Replace lockdep_hardirq_threaded() with lockdep annotation") Signed-off-by: Sasha Levin

Drivers: hv: Rename fields for SynIC message and event pages

2026-08-09T18:25:00+00:00

[ Upstream commit 163224c189e8b679ce919aa64ccabb7a992ca2d1 ] Confidential VMBus requires interacting with two SynICs -- one provided by the host hypervisor, and one provided by the paravisor. Each SynIC requires its own message and event pages. Rename the existing host-accessible SynIC message and event pages with the "hyp_" prefix to clearly distinguish them from the paravisor ones. The field name is also changed in mshv_root.* for consistency. No functional changes. Signed-off-by: Roman Kisel Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley Signed-off-by: Wei Liu Stable-dep-of: 8c7ab779c885 ("Drivers: hv: vmbus: Replace lockdep_hardirq_threaded() with lockdep annotation") Signed-off-by: Sasha Levin

mshv: add bounds check on vp_index in mshv_intercept_isr()

2026-07-24T14:16:20+00:00

[ Upstream commit a4ffc59238be84dd1c26bf1c001543e832674fc6 ] mshv_intercept_isr() extracts vp_index from the hypervisor message payload and uses it directly to index into pt_vp_array without validation. handle_bitset_message() and handle_pair_message() already validate vp_index against MSHV_MAX_VPS before array access. Add the same MSHV_MAX_VPS bounds check for consistency with the other message handlers. Fixes: 621191d709b1 ("Drivers: hv: Introduce mshv_root module to expose /dev/mshv to VMMs") Reported-by: Yuhao Jiang Signed-off-by: Junrui Luo Signed-off-by: Wei Liu Signed-off-by: Sasha Levin