diff options
| author | Stanislav Kinsburskii <skinsburskii@linux.microsoft.com> | 2026-05-07 15:43:43 +0000 |
|---|---|---|
| committer | Wei Liu <wei.liu@kernel.org> | 2026-07-31 20:01:57 +0000 |
| commit | 0289a67cd70bf9d3807e289f4efd643e16a6c6b4 (patch) | |
| tree | daf43615ac045b348f530e1f3486fdcb69c37842 | |
| parent | 0762262ac3e70f65b3bb843fe892f8bac1562d08 (diff) | |
mshv: Fix level-triggered check on uninitialized data
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 <skinsburskii@linux.microsoft.com>
Reviewed-by: Anirudh Rayabharam (Microsoft) <anirudh@anirudhrb.com>
Signed-off-by: Wei Liu <wei.liu@kernel.org>
| -rw-r--r-- | drivers/hv/mshv_eventfd.c | 25 |
1 files changed, 14 insertions, 11 deletions
diff --git a/drivers/hv/mshv_eventfd.c b/drivers/hv/mshv_eventfd.c index 5995a62aff8d..047e5bd43238 100644 --- a/drivers/hv/mshv_eventfd.c +++ b/drivers/hv/mshv_eventfd.c @@ -473,6 +473,19 @@ static int mshv_irqfd_assign(struct mshv_partition *pt, init_poll_funcptr(&irqfd->irqfd_polltbl, mshv_irqfd_queue_proc); spin_lock_irq(&pt->pt_irqfds_lock); + ret = 0; + hlist_for_each_entry(tmp, &pt->pt_irqfds_list, irqfd_hnode) { + if (irqfd->irqfd_eventfd_ctx != tmp->irqfd_eventfd_ctx) + continue; + /* This fd is used for another irq already. */ + ret = -EBUSY; + spin_unlock_irq(&pt->pt_irqfds_lock); + goto fail; + } + + idx = srcu_read_lock(&pt->pt_irq_srcu); + mshv_irqfd_update(pt, irqfd); + #if IS_ENABLED(CONFIG_X86) if (args->flags & BIT(MSHV_IRQFD_BIT_RESAMPLE) && !irqfd->irqfd_lapic_irq.lapic_control.level_triggered) { @@ -481,22 +494,12 @@ static int mshv_irqfd_assign(struct mshv_partition *pt, * Otherwise return with failure */ spin_unlock_irq(&pt->pt_irqfds_lock); + srcu_read_unlock(&pt->pt_irq_srcu, idx); ret = -EINVAL; goto fail; } #endif - ret = 0; - hlist_for_each_entry(tmp, &pt->pt_irqfds_list, irqfd_hnode) { - if (irqfd->irqfd_eventfd_ctx != tmp->irqfd_eventfd_ctx) - continue; - /* This fd is used for another irq already. */ - ret = -EBUSY; - spin_unlock_irq(&pt->pt_irqfds_lock); - goto fail; - } - idx = srcu_read_lock(&pt->pt_irq_srcu); - mshv_irqfd_update(pt, irqfd); hlist_add_head(&irqfd->irqfd_hnode, &pt->pt_irqfds_list); spin_unlock_irq(&pt->pt_irqfds_lock); |