2016-07-21 17:54+0100, Marc Zyngier:
> On 21/07/16 17:13, Radim Krčmář wrote:
>> 2016-07-18 13:25+0000, Eric Auger:
>>> Extend kvm_kernel_irq_routing_entry to transport the device id
>>> field, devid. A new flags field makes possible to indicate the
>>> devid is valid. Those additions are used for ARM GICv3 ITS MSI
>>> injection.
>>>
>>> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>>> Acked-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
>>>
>>> ---
>>> v6 -> v7:
>>> - added msi_ prefix to flags and dev_id fields
>>>
>>> v4 -> v5:
>>> - add Christoffer's R-b
>>>
>>> v2 -> v3:
>>> - add flags
>>>
>>> v1 -> v2:
>>> - replace msi_msg field by a struct composed of msi_msg and devid
>>>
>>> RFC -> PATCH:
>>> - reword the commit message after change in first patch (uapi)
>>> ---
>>> include/linux/kvm_host.h | 6 +++++-
>>> 1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>>> index c87fe6f..3d2cbb4 100644
>>> --- a/include/linux/kvm_host.h
>>> +++ b/include/linux/kvm_host.h
>>> @@ -317,7 +317,11 @@ struct kvm_kernel_irq_routing_entry {
>>> unsigned irqchip;
>>> unsigned pin;
>>> } irqchip;
>>> - struct msi_msg msi;
>>> + struct {
>>> + struct msi_msg msi;
>>> + u32 msi_flags;
>>> + u32 msi_devid;
>>
>> I'd much rather see them as msi.flags and msi.devid.
>
> That's not really possible, as msi_msg is the core data structure for
> MSIs, and nobody really expects this tructure to change.
>
>> I didn't notice a code that passes struct msi_msg anywhere, so using an
>> ad-hoc struct like irqchip or defining a new one would work fine.
>
> I guess we could have an arm-specific one:
>
> struct arm_msi {
> struct msi_msg msg;
> u32 flags;
> u32 devid;
> };
>
> and use that. Would that be OK with you?
The feature wants to be arch-neutral, so I would rather ignore struct
msi_msg. kvm_kernel_irq_routing_entry practically mirrors routing
entries from KVM API and there we have:
struct kvm_msi {
__u32 address_lo;
__u32 address_hi;
__u32 data;
__u32 flags;
__u32 devid;
__u8 pad[12];
};
I think that something like
struct {
u32 address_lo;
u32 address_hi;
u32 data;
u32 flags;
u32 devid;
} msi;
would get us consistency, minimal changes to existing code, no namespace
hierarchy, and no "." vs "_" mistakes at a good price of some code
duplication and concept separation.
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