• C
    genirq: Document vcpu_info usage for percpu_devid interrupts · 250a53d6
    Christoffer Dall 提交于
    It is currently unclear how to set the VCPU affinity for a percpu_devid
    interrupt , since the Linux irq_data structure describes the state for
    multiple interrupts, one for each physical CPU on the system.  Since
    each such interrupt can be associated with different VCPUs or none at
    all, associating a single VCPU state with such an interrupt does not
    capture the necessary semantics.
    
    The implementers of irq_set_affinity are the Intel and AMD IOMMUs, and
    the ARM GIC irqchip.  The Intel and AMD callers do not appear to use
    percpu_devid interrupts, and the ARM GIC implementation only checks the
    pointer against NULL vs. non-NULL.
    
    Therefore, simply update the function documentation to explain the
    expected use in the context of percpu_devid interrupts, allowing future
    changes or additions to irqchip implementers to do the right thing.
    Signed-off-by: NChristoffer Dall <cdall@linaro.org>
    Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
    Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
    Cc: kvm@vger.kernel.org
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Eric Auger <eric.auger@redhat.com>
    Cc: kvmarm@lists.cs.columbia.edu
    Cc: linux-arm-kernel@lists.infradead.org
    Link: https://lkml.kernel.org/r/1509093281-15225-13-git-send-email-cdall@linaro.org
    250a53d6
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