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fdba608f15
Drop a check that guards triggering a posted interrupt on the currently
running vCPU, and more importantly guards waking the target vCPU if
triggering a posted interrupt fails because the vCPU isn't IN_GUEST_MODE.
If a vIRQ is delivered from asynchronous context, the target vCPU can be
the currently running vCPU and can also be blocking, in which case
skipping kvm_vcpu_wake_up() is effectively dropping what is supposed to
be a wake event for the vCPU.
The "do nothing" logic when "vcpu == running_vcpu" mostly works only
because the majority of calls to ->deliver_posted_interrupt(), especially
when using posted interrupts, come from synchronous KVM context. But if
a device is exposed to the guest using vfio-pci passthrough, the VFIO IRQ
and vCPU are bound to the same pCPU, and the IRQ is _not_ configured to
use posted interrupts, wake events from the device will be delivered to
KVM from IRQ context, e.g.
vfio_msihandler()
|
|-> eventfd_signal()
|
|-> ...
|
|-> irqfd_wakeup()
|
|->kvm_arch_set_irq_inatomic()
|
|-> kvm_irq_delivery_to_apic_fast()
|
|-> kvm_apic_set_irq()
This also aligns the non-nested and nested usage of triggering posted
interrupts, and will allow for additional cleanups.
Fixes:
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|---|---|---|
| .. | ||
| alpha | ||
| arc | ||
| arm | ||
| arm64 | ||
| csky | ||
| h8300 | ||
| hexagon | ||
| ia64 | ||
| m68k | ||
| microblaze | ||
| mips | ||
| nds32 | ||
| nios2 | ||
| openrisc | ||
| parisc | ||
| powerpc | ||
| riscv | ||
| s390 | ||
| sh | ||
| sparc | ||
| um | ||
| x86 | ||
| xtensa | ||
| .gitignore | ||
| Kconfig | ||