Hi, On 03/07/15 10:05, Andre Przywara wrote: > Hi Pavel, > > On 02/07/15 08:26, 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. >> >>> @@ -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. > > I like this approach, but it runs into problems: > As you read above the current documentation says that the flags field > must be zero and the current KVM_SET_GSI_ROUTING handler bails out if it > isn't. So userland would need to know whether it's safe to set that > field. Introducing a new KVM_CAP_... value seems overkill if we could > just have a new routing entry type. So we could still reuse the existing > struct kvm_irq_routing_msi (and extend that with the devid field), but > we would have to add a new routing type number. > Maybe we could collapse this into the existing MSI type + flag when > handing it further down the kernel? FWIW, I gave this a try, this doesn't look to bad. I carried the new type down till virt/kvm/arm/vgic.c:kvm_set_routing_entry(), where the EXTENDED type got turned back into the normal MSI type while setting the flag in the internal struct kvm_kernel_irq_routing_entry. This keeps the new type only to the userland facing side, with the kernel code staying mostly the same. Together with a new KVM_CAP_MSIS_REQUIRE_DEVID capability I can now drive both GICv2M and ITS emulation from the same userland base in a sane manner. If someone wants to have a look now, tell me, otherwise I will wait for Eric's upcoming code drop and comment on that then. Cheers, Andre. > > Cheers, > Andre. > >> >>> >>> 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 >> -- 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
