From: Eric Auger <eric.auger@linaro.org>
To: Pavel Fedin <p.fedin@samsung.com>,
eric.auger@st.com, christoffer.dall@linaro.org,
marc.zyngier@arm.com, andre.przywara@arm.com,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: patches@linaro.org
Subject: Re: [RFC 0/6] KVM: arm/arm64: gsi routing support
Date: Mon, 22 Jun 2015 10:31:16 +0200 [thread overview]
Message-ID: <5587C7D4.2010408@linaro.org> (raw)
In-Reply-To: <011e01d0aa5a$6b14fae0$413ef0a0$@samsung.com>
Hi Pavel,
On 06/19/2015 08:37 AM, Pavel Fedin wrote:
> Hello!
>
>> The series therefore allows and mandates the usage of KVM_SET_GSI_ROUTING
>> ioctl along with KVM_IRQFD. If the userspace does not define any routing
>> table, no irqfd injection can happen. The user-space can use
>> KVM_CAP_IRQ_ROUTING to detect whether a routing table is needed.
>
> Yesterday, half-sleeping in the train back home, i've got a simple idea how to resolve
> conflicts with existing static GSI->SPI routing without bringing in any more
> inconsistencies.
> So far, in current implementation GSI is an SPI index (let alone KVM_IRQ_LINE, because
> it's already another story on ARM). In order to maintain this convention we could simply
> implement default routing which sets all GSIs to corresponding SPI pins. So, if the
> userland never cares about KVM_SET_GSI_ROUTING, everything works as before. But it will be
> possible to re-route GSIs to MSI. It will perfectly work because SPI signaling is used
> with GICv2m, and MSI with GICv3(+), which cannot be used at the same time.
I agree with you and I suggested the same approach in my cover letter.
Since applying GSI routing to KVM_IRQ_LINE is quite problematic, I would
be also in favour to forbid userspace GSI routing setting and implement
it kernel-side. Userspace would only be allowed to define MSI routing
entries.
I will respin accordingly and validate it further with qemu.
Best Regards
Eric
>
> Kind regards,
> Pavel Fedin
> Expert Engineer
> Samsung Electronics Research center Russia
>
>
next prev parent reply other threads:[~2015-06-22 8:20 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-18 17:40 [RFC 0/6] KVM: arm/arm64: gsi routing support Eric Auger
2015-06-18 17:40 ` [RFC 1/6] KVM: api: add kvm_irq_routing_extended_msi Eric Auger
2015-06-22 16:32 ` Andre Przywara
2015-06-23 7:36 ` Eric Auger
2015-06-18 17:40 ` [RFC 2/6] KVM: kvm_host: add kvm_extended_msi Eric Auger
2015-06-18 17:40 ` [RFC 3/6] KVM: irqchip: convey devid to kvm_set_msi Eric Auger
2015-06-18 17:40 ` [RFC 4/6] KVM: arm/arm64: enable irqchip routing Eric Auger
2015-06-18 17:53 ` Marc Zyngier
2015-06-18 18:00 ` Eric Auger
2015-06-18 18:07 ` Marc Zyngier
2015-06-18 17:40 ` [RFC 5/6] KVM: arm/arm64: enable MSI routing Eric Auger
2015-06-18 17:40 ` [RFC 6/6] KVM: arm: implement kvm_set_msi by gsi direct mapping Eric Auger
2015-06-19 6:37 ` [RFC 0/6] KVM: arm/arm64: gsi routing support Pavel Fedin
2015-06-22 8:31 ` Eric Auger [this message]
2015-06-22 8:40 ` Andre Przywara
2015-06-22 9:21 ` Eric Auger
2015-06-23 7:38 ` Pavel Fedin
2015-06-23 7:50 ` Eric Auger
2015-06-23 8:50 ` Pavel Fedin
2015-06-23 9:44 ` Eric Auger
2015-06-23 9:03 ` Andre Przywara
2015-06-23 9:33 ` Eric Auger
2015-06-23 12:53 ` Eric Auger
2015-06-24 12:20 ` Pavel Fedin
2015-06-24 13:03 ` Eric Auger
2015-06-25 8:46 ` Pavel Fedin
2015-06-26 16:17 ` Eric Auger
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