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Re: [Qemu-ppc] [PATCH 1/3] spapr pci msi: rework
From: |
Alexander Graf |
Subject: |
Re: [Qemu-ppc] [PATCH 1/3] spapr pci msi: rework |
Date: |
Fri, 21 Jun 2013 13:59:54 +0200 |
On 21.06.2013, at 13:58, Anthony Liguori wrote:
> Alexey Kardashevskiy <address@hidden> writes:
>
>> On 06/21/2013 08:31 PM, Alexander Graf wrote:
>>>
>>> On 21.06.2013, at 11:22, Alexey Kardashevskiy wrote:
>>>
>>>> Previously every PCI host bridge implemented its own MSI memory window
>>>> in order to catch msi_notify()/msix_notify() calls from various QEMU
>>>> MSI-capable devives such as virtio-pci or vfio and redirect them to
>>>> the guest via qemu_pulse_irq().
>>>
>>> That's how hardware works, no?
>>>
>>>>
>>>> The encoded MSIMessage used to be encoded as:
>>>> * .addr - address in a MSI window, this is how QEMU knows which PHB
>>>> is the message for;
>>>> * .data - number of a device on a specific PHB and vector number.
>>>>
>>>> As a PHB has a destriptor for every device, and every descriptor has
>>>> first IRQ number and the number of IRQs, it can calculate global IRQ
>>>> number to use in qemu_pulse_irq().
>>>
>>> How does this work on real hardware?
>>
>>
>> I do not understand the question, really. Here we are emulating pHyp which
>> is not real hardware and never pretended to be. Our guests do not touch MSI
>> records in the config space and use RTAS MSI calls instead.
>
> But RTAS is implemented as guest code. I suspect it's doing region
> access to generate the actual MSI events.
RTAS is actually implemented as a hypercall, which IIRC in our case modifies
the PCI config space registers directly.
ALex
[Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Alexey Kardashevskiy, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Alexander Graf, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Benjamin Herrenschmidt, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Alexander Graf, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Benjamin Herrenschmidt, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Alexander Graf, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Benjamin Herrenschmidt, 2013/06/21
- Re: [Qemu-ppc] [PATCH 2/3] KVM: add kvm_arch_irqchip_add_msi_route, Alexander Graf, 2013/06/21