Hi Vikas, On 11/17/20 9:05 AM, Auger Eric wrote: > Hi Vikas, > > On 11/17/20 7:25 AM, Vikas Gupta wrote: >> Hi Eric, >> >> On Mon, Nov 16, 2020 at 6:44 PM Auger Eric <eric.auger@xxxxxxxxxx> wrote: >>> >>> Hi Vikas, >>> >>> On 11/13/20 6:24 PM, Vikas Gupta wrote: >>>> Hi Eric, >>>> >>>> On Fri, Nov 13, 2020 at 12:10 AM Auger Eric <eric.auger@xxxxxxxxxx> wrote: >>>>> >>>>> Hi Vikas, >>>>> >>>>> On 11/12/20 6:58 PM, Vikas Gupta wrote: >>>>>> This RFC adds support for MSI for platform devices. >>>>>> a) MSI(s) is/are added in addition to the normal interrupts. >>>>>> b) The vendor specific MSI configuration can be done using >>>>>> callbacks which is implemented as msi module. >>>>>> c) Adds a msi handling module for the Broadcom platform devices. >>>>>> >>>>>> Changes from: >>>>>> ------------- >>>>>> v0 to v1: >>>>>> i) Removed MSI device flag VFIO_DEVICE_FLAGS_MSI. >>>>>> ii) Add MSI(s) at the end of the irq list of platform IRQs. >>>>>> MSI(s) with first entry of MSI block has count and flag >>>>>> information. >>>>>> IRQ list: Allocation for IRQs + MSIs are allocated as below >>>>>> Example: if there are 'n' IRQs and 'k' MSIs >>>>>> ------------------------------------------------------- >>>>>> |IRQ-0|IRQ-1|....|IRQ-n|MSI-0|MSI-1|MSI-2|......|MSI-k| >>>>>> ------------------------------------------------------- >>>>> I have not taken time yet to look at your series, but to me you should have >>>>> |IRQ-0|IRQ-1|....|IRQ-n|MSI|MSIX >>>>> then for setting a given MSIX (i) you would select the MSIx index and >>>>> then set start=i count=1. >>>> >>>> As per your suggestion, we should have, if there are n-IRQs, k-MSIXs >>>> and m-MSIs, allocation of IRQs should be done as below >>>> >>>> |IRQ0|IRQ1|......|IRQ-(n-1)|MSI|MSIX| >>>> | | >>>> | >>>> |MSIX0||MSIX1||MSXI2|....|MSIX-(k-1)| >>>> |MSI0||MSI1||MSI2|....|MSI-(m-1)| >>> No I really meant this list of indices: IRQ0|IRQ1|......|IRQ-(n-1)|MSI|MSIX| >>> and potentially later on IRQ0|IRQ1|......|IRQ-(n-1)|MSI|MSIX| ERR| REQ >>> if ERR/REQ were to be added. >> I agree on this. Actually the map I drew incorrectly above but wanted >> to demonstrate the same. It was a child-parent relationship for MSI >> and its members and similarly for MSIX as well. >>> >>> I think the userspace could query the total number of indices using >>> VFIO_DEVICE_GET_INFO and retrieve num_irqs (corresponding to the n wire >>> interrupts + MSI index + MSIX index) >>> >>> Then userspace can loop on all the indices using >>> VFIO_DEVICE_GET_IRQ_INFO. For each index it uses count to determine the >>> first indices related to wire interrupts (count = 1). Then comes the MSI >>> index, and after the MSI index. If any of those is supported, count >1, >>> otherwise count=0. The only thing I am dubious about is can the device >>> use a single MSI/MSIX? Because my hypothesis here is we use count to >>> discriminate between wire first indices and other indices. >> I believe count can be one as well, especially for ERR/REQ as you >> mentioned above. > Given ERR and REQ indices would follow MSI and MSIX ones, MSI index > could be recognized by the first index whose count != 1. But indeed I am > not sure the number of supported vectors cannot be 1. In your case it is > induced by the size of the ring so it is OK but for other devices this > may be different. > > I think we can not rely on the count > 1. Now, this is >> blocking and we are not left with options unless we consider adding >> more enums in flags in vfio_irq_info to tell userspace that particular >> index is wired, MSI, MSIX etc. for the platform device. >> What do you think? > If count is not reliable to discriminate the first n wired interrupts > from the subsequen MSI and MSIx index, Alex suggested to add a > capability extension in the vfio_irq_info structure. Something similar > to what was done for vfio_region_info. > > Such kind of thing was attempted in > https://lore.kernel.org/kvmarm/20201116110030.32335-8-eric.auger@xxxxxxxxxx/T/#u > > ` [PATCH v11 07/13] vfio: Use capability chains to handle device > specific irq > ` [PATCH v11 08/13] vfio/pci: Add framework for custom interrupt indices > ` [PATCH v11 09/13] vfio: Add new IRQ for DMA fault reporting By the way I was mentionning MSI/MSIx in my previous reply but, as Alex pointed out, with platform device only a single MSI index does make sense, no? Thanks Eric > > Note this has not been reviewed yet. > > Thanks > > Eric > >>> >>> >>> >>>> With this implementation user space can know that, at indexes n and >>>> n+1, edge triggered interrupts are present. >>> note wired interrupts can also be edge ones. >>>> We may add an element in vfio_platform_irq itself to allocate MSIs/MSIXs >>>> struct vfio_platform_irq{ >>>> ..... >>>> ..... >>>> struct vfio_platform_irq *block; => this points to the block >>>> allocation for MSIs/MSIXs and all msi/msix are type of IRQs.As wired interrupts and MSI interrupts coexist, I would store in vdev an >>> array of wired interrupts (the existing vdev->irqs) and a new array for >>> MSI(x) as done in the PCI code. >>> >>> vdev->ctx = kcalloc(nvec, sizeof(struct vfio_pci_irq_ctx), GFP_KERNEL); >>> >>> Does it make sense? >> Yes, we can use similar kinds of allocations. >> >> Thanks, >> Vikas >>> >>>> }; >>>> OR >>>> Another structure can be defined in 'vfio_pci_private.h' >>>> struct vfio_msi_ctx { >>>> struct eventfd_ctx *trigger; >>>> char *name; >>>> }; >>>> and >>>> struct vfio_platform_irq { >>>> ..... >>>> ..... >>>> struct vfio_msi_ctx *block; => this points to the block allocation >>>> for MSIs/MSIXs >>>> }; >>>> Which of the above two options sounds OK to you? Please suggest. >>>> >>>>> to me individual MSIs are encoded in the subindex and not in the index. >>>>> The index just selects the "type" of interrupt. >>>>> >>>>> For PCI you just have: >>>>> VFIO_PCI_INTX_IRQ_INDEX, >>>>> VFIO_PCI_MSI_IRQ_INDEX, -> MSI index and then you play with >>>>> start/count >>>>> VFIO_PCI_MSIX_IRQ_INDEX, >>>>> VFIO_PCI_ERR_IRQ_INDEX, >>>>> VFIO_PCI_REQ_IRQ_INDEX, >>>>> >>>>> (include/uapi/linux/vfio.h) >>>> >>>> In pci case, type of interrupts is fixed so they can be 'indexed' by >>>> these enums but for VFIO platform user space will need to iterate all >>>> (num_irqs) indexes to know at which indexes edge triggered interrupts >>>> are present. >>> indeed, but can't you loop over all indices looking until count !=1? At >>> this point you know if have finished emurating the wires. Holds if >>> MSI(x) count !=1 of course. >>> >>> Thanks >>> >>> Eric >>> >>>> >>>> Thanks, >>>> Vikas >>>>> >>>>> Thanks >>>>> >>>>> Eric >>>>>> MSI-0 will have count=k set and flags set accordingly. >>>>>> >>>>>> Vikas Gupta (3): >>>>>> vfio/platform: add support for msi >>>>>> vfio/platform: change cleanup order >>>>>> vfio/platform: add Broadcom msi module >>>>>> >>>>>> drivers/vfio/platform/Kconfig | 1 + >>>>>> drivers/vfio/platform/Makefile | 1 + >>>>>> drivers/vfio/platform/msi/Kconfig | 9 + >>>>>> drivers/vfio/platform/msi/Makefile | 2 + >>>>>> .../vfio/platform/msi/vfio_platform_bcmplt.c | 74 ++++++ >>>>>> drivers/vfio/platform/vfio_platform_common.c | 86 ++++++- >>>>>> drivers/vfio/platform/vfio_platform_irq.c | 238 +++++++++++++++++- >>>>>> drivers/vfio/platform/vfio_platform_private.h | 23 ++ >>>>>> 8 files changed, 419 insertions(+), 15 deletions(-) >>>>>> create mode 100644 drivers/vfio/platform/msi/Kconfig >>>>>> create mode 100644 drivers/vfio/platform/msi/Makefile >>>>>> create mode 100644 drivers/vfio/platform/msi/vfio_platform_bcmplt.c >>>>>> >>>>> >>>
