On 07.08.2020 01:49, Stefano Stabellini wrote: > On Thu, 6 Aug 2020, Julien Grall wrote: >> On 06/08/2020 01:37, Stefano Stabellini wrote: >>> On Wed, 5 Aug 2020, Julien Grall wrote: >>>> On 05/08/2020 00:22, Stefano Stabellini wrote: >>>>> On Mon, 3 Aug 2020, Oleksandr Tyshchenko wrote: >>>>>> From: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com> >>>>>> >>>>>> This patch adds ability to the device emulator to notify otherend >>>>>> (some entity running in the guest) using a SPI and implements Arm >>>>>> specific bits for it. Proposed interface allows emulator to set >>>>>> the logical level of a one of a domain's IRQ lines. >>>>>> >>>>>> Please note, this is a split/cleanup of Julien's PoC: >>>>>> "Add support for Guest IO forwarding to a device emulator" >>>>>> >>>>>> Signed-off-by: Julien Grall <julien.gr...@arm.com> >>>>>> Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshche...@epam.com> >>>>>> --- >>>>>> tools/libs/devicemodel/core.c | 18 >>>>>> ++++++++++++++++++ >>>>>> tools/libs/devicemodel/include/xendevicemodel.h | 4 ++++ >>>>>> tools/libs/devicemodel/libxendevicemodel.map | 1 + >>>>>> xen/arch/arm/dm.c | 22 >>>>>> +++++++++++++++++++++- >>>>>> xen/common/hvm/dm.c | 1 + >>>>>> xen/include/public/hvm/dm_op.h | 15 >>>>>> +++++++++++++++ >>>>>> 6 files changed, 60 insertions(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/tools/libs/devicemodel/core.c >>>>>> b/tools/libs/devicemodel/core.c >>>>>> index 4d40639..30bd79f 100644 >>>>>> --- a/tools/libs/devicemodel/core.c >>>>>> +++ b/tools/libs/devicemodel/core.c >>>>>> @@ -430,6 +430,24 @@ int xendevicemodel_set_isa_irq_level( >>>>>> return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op)); >>>>>> } >>>>>> +int xendevicemodel_set_irq_level( >>>>>> + xendevicemodel_handle *dmod, domid_t domid, uint32_t irq, >>>>>> + unsigned int level) >>>>> >>>>> It is a pity that having xen_dm_op_set_pci_intx_level and >>>>> xen_dm_op_set_isa_irq_level already we need to add a third one, but from >>>>> the names alone I don't think we can reuse either of them. >>>> >>>> The problem is not the name... >>>> >>>>> >>>>> It is very similar to set_isa_irq_level. We could almost rename >>>>> xendevicemodel_set_isa_irq_level to xendevicemodel_set_irq_level or, >>>>> better, just add an alias to it so that xendevicemodel_set_irq_level is >>>>> implemented by calling xendevicemodel_set_isa_irq_level. Honestly I am >>>>> not sure if it is worth doing it though. Any other opinions? >>>> >>>> ... the problem is the interrupt field is only 8-bit. So we would only be >>>> able >>>> to cover IRQ 0 - 255. >>> >>> Argh, that's not going to work :-( I wasn't sure if it was a good idea >>> anyway. >>> >>> >>>> It is not entirely clear how the existing subop could be extended without >>>> breaking existing callers. >>>> >>>>> But I think we should plan for not needing two calls (one to set level >>>>> to 1, and one to set it to 0): >>>>> https://marc.info/?l=xen-devel&m=159535112027405 >>>> >>>> I am not sure to understand your suggestion here? Are you suggesting to >>>> remove >>>> the 'level' parameter? >>> >>> My hope was to make it optional to call the hypercall with level = 0, >>> not necessarily to remove 'level' from the struct. >> >> From my understanding, the hypercall is meant to represent the status of the >> line between the device and the interrupt controller (either low or high). >> >> This is then up to the interrupt controller to decide when the interrupt is >> going to be fired: >> - For edge interrupt, this will fire when the line move from low to high >> (or >> vice versa). >> - For level interrupt, this will fire when line is high (assuming level >> trigger high) and will keeping firing until the device decided to lower the >> line. >> >> For a device, it is common to keep the line high until an OS wrote to a >> specific register. >> >> Furthermore, technically, the guest OS is in charge to configure how an >> interrupt is triggered. Admittely this information is part of the DT, but >> nothing prevent a guest to change it. >> >> As side note, we have a workaround in Xen for some buggy DT (see the arch >> timer) exposing the wrong trigger type. >> >> Because of that, I don't really see a way to make optional. Maybe you have >> something different in mind? > > For level, we need the level parameter. For edge, we are only interested > in the "edge", right?
I don't think so, unless Arm has special restrictions. Edges can be both rising and falling ones. Jan
