Hi Andre, On 07/02/2015 05:14 PM, Andre Przywara wrote: > Hi Eric, > > On 02/07/15 15:49, Eric Auger wrote: >> Hi Pavel, >> On 07/02/2015 09:26 AM, Pavel Fedin wrote: >>> Hello! >>> >>>> -----Original Message----- >>>> From: kvm-owner@xxxxxxxxxxxxxxx [mailto:kvm-owner@xxxxxxxxxxxxxxx] On Behalf Of Eric Auger >>>> Sent: Monday, June 29, 2015 6:37 PM >>>> To: eric.auger@xxxxxx; eric.auger@xxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; >>>> marc.zyngier@xxxxxxx; christoffer.dall@xxxxxxxxxx; andre.przywara@xxxxxxx; >>>> kvmarm@xxxxxxxxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx >>>> Cc: linux-kernel@xxxxxxxxxxxxxxx; patches@xxxxxxxxxx; p.fedin@xxxxxxxxxxx; pbonzini@xxxxxxxxxx >>>> Subject: [PATCH 1/7] KVM: api: add kvm_irq_routing_extended_msi >>>> >>>> On ARM, the MSI msg (address and data) comes along with >>>> out-of-band device ID information. The device ID encodes the device >>>> that composes the MSI msg. Let's create a new routing entry type, >>>> dubbed KVM_IRQ_ROUTING_EXTENDED_MSI and use the __u32 pad space >>>> to convey the device ID. >>>> >>>> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx> >>>> >>>> --- >>>> >>>> RFC -> PATCH >>>> - remove kvm_irq_routing_extended_msi and use union instead >>>> --- >>>> Documentation/virtual/kvm/api.txt | 9 ++++++++- >>>> include/uapi/linux/kvm.h | 6 +++++- >>>> 2 files changed, 13 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt >>>> index d20fd94..6426ae9 100644 >>>> --- a/Documentation/virtual/kvm/api.txt >>>> +++ b/Documentation/virtual/kvm/api.txt >>>> @@ -1414,7 +1414,10 @@ struct kvm_irq_routing_entry { >>>> __u32 gsi; >>>> __u32 type; >>>> __u32 flags; >>>> - __u32 pad; >>>> + union { >>>> + __u32 pad; >>>> + __u32 devid; >>>> + }; >>>> union { >>>> struct kvm_irq_routing_irqchip irqchip; >>>> struct kvm_irq_routing_msi msi; >>> >>> devid is actually a part of MSI bunch. Shouldn't it be a part of struct kvm_irq_routing_msi then? >>> It also has reserved pad. >> Well this makes sense to me to associate the devid to the msi and put >> devid in the pad field of struct kvm_irq_routing_msi. >> >> André, Christoffer, would you agree on this change? - I would like to >> avoid doing/undoing things ;-) - > > Yes, that makes sense to me. TBH I haven't had a closer look at the > patches yet, but clearly devid belongs into struct kvm_irq_routing_msi. thanks for your quick reply. OK so let's go with that change. > >>> >>>> @@ -1427,6 +1430,10 @@ struct kvm_irq_routing_entry { >>>> #define KVM_IRQ_ROUTING_IRQCHIP 1 >>>> #define KVM_IRQ_ROUTING_MSI 2 >>>> #define KVM_IRQ_ROUTING_S390_ADAPTER 3 >>>> +#define KVM_IRQ_ROUTING_EXTENDED_MSI 4 >>>> + >>>> +In case of KVM_IRQ_ROUTING_EXTENDED_MSI routing type, devid is used to convey >>>> +the device ID. >>>> >>>> No flags are specified so far, the corresponding field must be set to zero. >>> >>> What if we use KVM_MSI_VALID_DEVID flag instead of new KVM_IRQ_ROUTING_EXTENDED_MSI definition? I >>> believe this would make an API more consistent and introduce less new definitions. >> do you mean using type == KVM_IRQ_ROUTING_MSI and flag == >> KVM_MSI_VALID_DEVID? Not sure this is simpler/clearer. s390 paved the >> way for new routing entry types. I add a new one here. > > I tend to agree with Pavel's solution. When hacking IRQ routing support > into kvmtool I saw that it's nasty being forced to differentiate between > the two MSI routing types. Actually userland should be able to query the > kernel about what kind of routing it requires. Also there is the issue > that we must _not_ set the flag on x86, since that breaks older kernels > (due to that check that Eric removes in 3/7). > So from my point of view the cleanest solution would be to always use > KVM_IRQ_ROUTING_MSI, and add the device ID if the kernel needs it (true > for ITS guests, false for GICv2M, x86, ...) > I am looking for a clever solution for this now. OK thanks for sharing. I need some more time to study qemu code too. - Eric > > Cheers, > Andre. > >> >> Another solution may be to use new KVM_IRQ_ROUTING_EXTENDED_MSI type and >> add struct kvm_msi ext_msi in kvm_irq_routing_entry union. It is 8 words >> as well. But most probably this is even uglier. > >> >> Let's see if this thread is heading to a consensus... >> >> Best Regards >> >> Eric >>> >>>> >>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h >>>> index 2a23705..8484681 100644 >>>> --- a/include/uapi/linux/kvm.h >>>> +++ b/include/uapi/linux/kvm.h >>>> @@ -841,12 +841,16 @@ struct kvm_irq_routing_s390_adapter { >>>> #define KVM_IRQ_ROUTING_IRQCHIP 1 >>>> #define KVM_IRQ_ROUTING_MSI 2 >>>> #define KVM_IRQ_ROUTING_S390_ADAPTER 3 >>>> +#define KVM_IRQ_ROUTING_EXTENDED_MSI 4 >>>> >>>> struct kvm_irq_routing_entry { >>>> __u32 gsi; >>>> __u32 type; >>>> __u32 flags; >>>> - __u32 pad; >>>> + union { >>>> + __u32 pad; >>>> + __u32 devid; >>>> + }; >>>> union { >>>> struct kvm_irq_routing_irqchip irqchip; >>>> struct kvm_irq_routing_msi msi; >>>> -- >>>> 1.9.1 >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe kvm" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> Kind regards, >>> Pavel Fedin >>> Expert Engineer >>> Samsung Electronics Research center Russia >>> >> _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
