From: Marc Zyngier <marc.zyngier@arm.com>
To: Auger Eric <eric.auger@redhat.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Andre Przywara <Andre.Przywara@arm.com>,
Shameerali Kolothum Thodi <shameerali.kolothum.thodi@huawei.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Shanker Donthineni <shankerd@codeaurora.org>
Subject: Re: [PATCH v5 26/26] KVM: arm/arm64: GICv4: Theory of operations
Date: Wed, 8 Nov 2017 15:19:36 +0000 [thread overview]
Message-ID: <39032d1d-3371-1751-6981-f30811db19a8@arm.com> (raw)
In-Reply-To: <98265bff-57ca-a31e-f41c-75b41a4e34f7@redhat.com>
On 08/11/17 09:13, Auger Eric wrote:
> Hi Marc,
>
> On 27/10/2017 16:28, Marc Zyngier wrote:
>> Yet another braindump so I can free some cells...
>>
>> Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> ---
>> virt/kvm/arm/vgic/vgic-v4.c | 67 +++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 67 insertions(+)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
>> index d10e18eabd3b..e367d65a0ebe 100644
>> --- a/virt/kvm/arm/vgic/vgic-v4.c
>> +++ b/virt/kvm/arm/vgic/vgic-v4.c
>> @@ -23,6 +23,73 @@
>>
>> #include "vgic.h"
>>
>> +/*
>> + * How KVM uses GICv4 (insert rude comments here):
>> + *
>> + * The vgic-v4 layer acts as a bridge between several entities:
>> + * - The GICv4 ITS representation offered by the ITS driver
>> + * - VFIO, which is in charge of the PCI endpoint
>> + * - The virtual ITS, which is the only thing the guest sees
>> + *
>> + * The configuration of VLPIs is triggered by a callback from VFIO,
>> + * instructing KVM that a PCI device has been configured to deliver
>> + * MSIs to a vITS.
> We actually have a negotiation protocol between VFIO PCI (irq bypass
> producer) and KVM irqfd (IRQ bypass consumer). When both recognize they
> are tied together, handling an MSI tunneling, they initiate the
> forwarding setup.
>> + *
>> + * kvm_vgic_v4_set_forwarding() is thus called with the routing entry,
>> + * and this is used to find the corresponding vITS data structures
>> + * (ITS instance, device, event and irq) using a process that is
>> + * extremely similar to the injection of an MSI.
>
> Is it correct to say we replace the following injection chain:
>
> pEventID|
> (pITS) |-> pLPIID -> VFIO PCI IRQ handler -> KVM irqfd ...
> pDevID |
>
> vEventID|
> ... inject (vITS) | -> vLPIID
> vDevID |
>
> by
>
> pEventID|
> (pITS) | -> vLPIID
> pDevID |
That's indeed a pretty accurate description of what happens, with a side
messaging (doorbells).
Thanks,
M.
--
Jazz is not dead. It just smells funny...
prev parent reply other threads:[~2017-11-08 15:19 UTC|newest]
Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-27 14:28 [PATCH v5 00/26] KVM/ARM: Add support for GICv4 Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 01/26] irqchip/gic-v3-its: Setup VLPI properties at map time Marc Zyngier
2017-10-30 6:46 ` Christoffer Dall
2017-10-27 14:28 ` [PATCH v5 02/26] KVM: arm/arm64: register irq bypass consumer on ARM/ARM64 Marc Zyngier
2017-10-30 6:47 ` Christoffer Dall
2017-10-27 14:28 ` [PATCH v5 03/26] KVM: arm/arm64: vgic: restructure kvm_vgic_(un)map_phys_irq Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 04/26] KVM: arm: Select ARM_GIC_V3 and ARM_GIC_V3_ITS Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 05/26] KVM: arm/arm64: vgic: Move kvm_vgic_destroy call around Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 06/26] KVM: arm/arm64: vITS: Add MSI translation helpers Marc Zyngier
2017-11-07 20:34 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 07/26] KVM: arm/arm64: vITS: Add a helper to update the affinity of an LPI Marc Zyngier
2017-11-07 13:44 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 08/26] KVM: arm/arm64: GICv4: Add property field and per-VM predicate Marc Zyngier
2017-11-07 20:30 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 09/26] KVM: arm/arm64: GICv4: Add init/teardown of the per-VM vPE irq domain Marc Zyngier
2017-11-07 13:08 ` Auger Eric
2017-11-10 8:20 ` Christoffer Dall
2017-11-10 8:55 ` Marc Zyngier
2017-11-07 13:09 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 10/26] KVM: arm/arm64: GICv4: Wire mapping/unmapping of VLPIs in VFIO irq bypass Marc Zyngier
2017-11-07 13:06 ` Auger Eric
2017-11-07 14:42 ` Marc Zyngier
2017-11-07 15:59 ` Auger Eric
2017-11-08 11:30 ` Marc Zyngier
2017-11-10 8:28 ` Christoffer Dall
2017-11-10 9:05 ` Marc Zyngier
2017-11-10 9:41 ` Christoffer Dall
2017-10-27 14:28 ` [PATCH v5 11/26] KVM: arm/arm64: GICv4: Handle INT command applied to a VLPI Marc Zyngier
2017-11-07 20:15 ` Auger Eric
2017-11-08 11:40 ` Marc Zyngier
2017-11-08 14:14 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 12/26] KVM: arm/arm64: GICv4: Unmap VLPI when freeing an LPI Marc Zyngier
2017-11-07 20:28 ` Auger Eric
2017-11-08 11:52 ` Marc Zyngier
2017-11-08 14:14 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 13/26] KVM: arm/arm64: GICv4: Propagate affinity changes to the physical ITS Marc Zyngier
2017-11-07 21:01 ` Auger Eric
2017-11-08 12:05 ` Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 14/26] KVM: arm/arm64: GICv4: Handle CLEAR applied to a VLPI Marc Zyngier
2017-11-07 21:04 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 15/26] KVM: arm/arm64: GICv4: Handle MOVALL applied to a vPE Marc Zyngier
2017-11-07 21:06 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 16/26] KVM: arm/arm64: GICv4: Propagate property updates to VLPIs Marc Zyngier
2017-11-07 21:28 ` Auger Eric
2017-11-08 15:08 ` Marc Zyngier
2017-11-10 8:37 ` Christoffer Dall
2017-11-10 8:58 ` Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 17/26] KVM: arm/arm64: GICv4: Handle INVALL applied to a vPE Marc Zyngier
2017-11-07 21:23 ` Auger Eric
2017-11-10 8:41 ` Christoffer Dall
2017-11-10 8:56 ` Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 18/26] KVM: arm/arm64: GICv4: Use pending_last as a scheduling hint Marc Zyngier
2017-11-07 21:38 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 19/26] KVM: arm/arm64: GICv4: Add doorbell interrupt handling Marc Zyngier
2017-11-07 21:43 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 20/26] KVM: arm/arm64: GICv4: Use the doorbell interrupt as an unblocking source Marc Zyngier
2017-11-07 21:45 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 21/26] KVM: arm/arm64: GICv4: Hook vPE scheduling into vgic flush/sync Marc Zyngier
2017-11-07 21:54 ` Auger Eric
2017-11-07 22:14 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 22/26] KVM: arm/arm64: GICv4: Enable virtual cpuif if VLPIs can be delivered Marc Zyngier
2017-11-08 8:46 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 23/26] KVM: arm/arm64: GICv4: Prevent a VM using GICv4 from being saved Marc Zyngier
2017-11-07 15:24 ` Auger Eric
2017-11-07 15:38 ` Marc Zyngier
2017-11-07 16:12 ` Auger Eric
2017-11-07 16:34 ` Marc Zyngier
2017-11-07 22:24 ` Auger Eric
2017-11-08 9:35 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 24/26] KVM: arm/arm64: GICv4: Prevent userspace from changing doorbell affinity Marc Zyngier
2017-10-30 6:51 ` Christoffer Dall
2017-11-07 22:17 ` Auger Eric
2017-10-27 14:28 ` [PATCH v5 25/26] KVM: arm/arm64: GICv4: Enable VLPI support Marc Zyngier
2017-11-08 8:44 ` Auger Eric
2017-11-08 15:14 ` Marc Zyngier
2017-10-27 14:28 ` [PATCH v5 26/26] KVM: arm/arm64: GICv4: Theory of operations Marc Zyngier
2017-11-08 9:13 ` Auger Eric
2017-11-08 15:19 ` Marc Zyngier [this message]
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