On 20.03.25 15:07, Oleksandr Tyshchenko wrote:
>>> If I got correctly what is wrote in current thread (and in RFC version
>>> where it was an attempt to create just Arm64's counterpart of
>>> XEN_DMOP_inject_msi), my understanding (maybe not precise/correct, since
>>> I am not quite familiar with x86 details) that we would need something
>>> like that:
>>>
>>>
>>> /*
>>> * XEN_DMOP_inject_msi2: An enhanced version of the sub-ob to
>>> inject an MSI
>>> * for an emulated device, which allows
>>> specifying
>>> * the ID of the device triggering the MSI
>>> (source ID).
>>> *
>>> * The source ID is specified by a pair of <segment> and <source_id>.
>>> * If <flags> does not contain XEN_DMOP_MSI_SOURCE_ID_VALID then
>>> source ID
>>> * is invalid and should be ignored.
>>> */
>>> #define XEN_DMOP_inject_msi 21
>>>
>>> struct xen_dm_op_inject_msi2 {
>>> /* IN - MSI data */
>>> uint32_t data;
>>> /* IN - next two fields form an ID of the device triggering
>>> the MSI */
>>> uint16_t segment; /* The segment number */
>>> uint16_t source_id; /* The source ID that is local to segment
>>> (PCI
>>> BDF) */
>>> /* IN - types of source ID */
>>> uint32_t flags;
>>> #define XEN_DMOP_MSI_SOURCE_ID_VALID (1u << 0)
>>> uint32_t pad;
>>> /* IN - MSI address */
>>> uint64_aligned_t addr;
>>> };
>>>
>>>
>>> This is arch agnostic sub-op without the (obvious) specifics of the
>>> underlying MSI controller. The sub-ob, I hope, will be suitable on both
>>> Arm64 soon (segment + source_id provide vSBDF, then it will possible to
>>> locate vITS and devid) and on x86 in future (for the vIOMMU needs).
>>>
>>> Would you be ok with that in general? Please share you opinion.
>>
>> Yes, this looks plausible.
>
> Jan, thanks
>
>
> In the context of things like VMD (using
>> software established segment numbers wider than 16 bits) I wonder
>> though whether we wouldn't better make segment and source ID 32-bit
>> fields from the beginning.
>
> Keeping in mind that dm_op hypercall is stable and segment can be >=
> 0x10000, probably yes, makes sense to use 32-bit from the very beginning.
>
>
> Out-of-range values would of course need
>> rejecting then.
>
> yes, sure
>
> ***
>
> Mykyta, are you ok with the proposed adjustments to the sub-op structure?
>
>>
>> Jan
Yes, seems fine for me. I will use it in the next version.
--
Mykyta
