Re: [PATCH v11 00/20] VFIO support for platform and ARM AMBA devices

[Eric Auger <eric.auger-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

Hi Antonios,

when moving to 3.19rc3 I observe a regression with my xgmac use case
(real-time change?).

I guess what happens is when I kill a first qemu session, guest does not
have time to complete the virtual IRQ and the unmask is not performed by
the virqfd handler. When starting a new QEMU session, the irqfd
signalling is put in place again but since the masked field is set, the
IRQ is left unmasked (v11 modification in vfio_set_trigger).

The problem is that we don't discriminate between user mask action and
automasked handler action. In case the user did not mask, I think we
should reset the masked field when doing the free_irq. What do you think?

Best Regards

Eric

On 01/06/2015 11:48 AM, Antonios Motakis wrote:
> This patch series aims to implement VFIO support for platform devices that
> reside behind an IOMMU. Examples of such devices are devices behind an ARM
> SMMU, or behind a Samsung Exynos System MMU.
> 
> The API used is based on the existing VFIO API that is also used with PCI
> devices. Only devices that include a basic set of IRQs and memory regions are
> targeted; devices with complex relationships with other devices on a device
> tree are not taken into account at this stage.
> 
> This patch series may be applied on the following series/patches:
>  - [PATCH] driver core: amba: add device binding path 'driver_override'
>  - [PATCH v3 0/6] vfio: type1: support for ARM SMMUS with VFIO_IOMMU_TYPE1
> 
> A copy can be cloned from the branch vfio-platform-v11 at:
> git-9UaJU3cA/F/QT0dZR+AlfA@public.gmane.org:virtualopensystems/linux-kvm-arm.git
> 
> Changes since v10:
>  - Check if interrupt is already masked when setting a new trigger
>  - Fixed kasprintf with unchecked return value in VFIO AMBA driver
> Changes since v9:
>  - Reworked the splitting of the patches that decouple virqfd from PCI
>  - Some styling issues and typos
>  - Removed superfluous includes
>  - AMBA devices are now named vfio-amba- suffixed by the AMBA device id
>  - Several other cleanups and fixes
> Changes since v8:
>  - Separate irq handler for edge and level triggered interrupts
>  - Mutex based lock for VFIO fd open/release
>  - Fixed bug where the first region of a platform device wasn't exposed
>  - Read only regions can be MMAPed only read only
>  - Code cleanups
> Changes since v7:
>  - Some initial placeholder functionality for PIO resources
>  - Cleaned up code for IRQ triggering, masking and unmasking
>  - Some functionality has been removed from this series and posted separately:
>    - VFIO_IOMMU_TYPE1 support for ARM SMMUs
>    - IOMMU NOEXEC patches
>    - driver_override functionality for AMBA devices
>  - Several fixes
> Changes since v6:
>  - Integrated support for AMBA devices
>  - Numerous cleanups and fixes
> Changes since v5:
>  - Full eventfd support for IRQ masking and unmasking.
>  - Changed IOMMU_EXEC to IOMMU_NOEXEC, along with related flags in VFIO.
>  - Other fixes based on reviewer comments.
> Changes since v4:
>  - Use static offsets for each region in the VFIO device fd
>  - Include patch in the series for the ARM SMMU to expose IOMMU_EXEC
>    availability via IOMMU_CAP_DMA_EXEC
>  - Rebased on VFIO multi domain support:
>    - IOMMU_EXEC is now available if at least one IOMMU in the container
>      supports it
>    - Expose IOMMU_EXEC if available via the capability VFIO_IOMMU_PROT_EXEC
>  - Some bug fixes
> Changes since v3:
>  - Use Kim Phillips' driver_probe_device()
> Changes since v2:
>  - Fixed Read/Write and MMAP on device regions
>  - Removed dependency on Device Tree
>  - Interrupts support
>  - Interrupt masking/unmasking
>  - Automask level sensitive interrupts
>  - Introduced VFIO_DMA_MAP_FLAG_EXEC
>  - Code clean ups
> 
> Antonios Motakis (20):
>   vfio/platform: initial skeleton of VFIO support for platform devices
>   vfio: platform: probe to devices on the platform bus
>   vfio: platform: add the VFIO PLATFORM module to Kconfig
>   vfio: amba: VFIO support for AMBA devices
>   vfio: amba: add the VFIO for AMBA devices module to Kconfig
>   vfio/platform: return info for bound device
>   vfio/platform: return info for device memory mapped IO regions
>   vfio/platform: read and write support for the device fd
>   vfio/platform: support MMAP of MMIO regions
>   vfio/platform: return IRQ info
>   vfio/platform: initial interrupts support code
>   vfio/platform: trigger an interrupt via eventfd
>   vfio/platform: support for level sensitive interrupts
>   vfio: add a vfio_ prefix to virqfd_enable and virqfd_disable and
>     export
>   vfio: virqfd: rename vfio_pci_virqfd_init and vfio_pci_virqfd_exit
>   vfio: add local lock for virqfd instead of depending on VFIO PCI
>   vfio: pass an opaque pointer on virqfd initialization
>   vfio: move eventfd support code for VFIO_PCI to a separate file
>   vfio: initialize the virqfd workqueue in VFIO generic code
>   vfio/platform: implement IRQ masking/unmasking via an eventfd
> 
>  drivers/vfio/Kconfig                          |   1 +
>  drivers/vfio/Makefile                         |   5 +-
>  drivers/vfio/pci/vfio_pci.c                   |   8 -
>  drivers/vfio/pci/vfio_pci_intrs.c             | 238 +-----------
>  drivers/vfio/pci/vfio_pci_private.h           |   3 -
>  drivers/vfio/platform/Kconfig                 |  19 +
>  drivers/vfio/platform/Makefile                |   8 +
>  drivers/vfio/platform/vfio_amba.c             | 115 ++++++
>  drivers/vfio/platform/vfio_platform.c         | 103 +++++
>  drivers/vfio/platform/vfio_platform_common.c  | 520 ++++++++++++++++++++++++++
>  drivers/vfio/platform/vfio_platform_irq.c     | 340 +++++++++++++++++
>  drivers/vfio/platform/vfio_platform_private.h |  82 ++++
>  drivers/vfio/vfio.c                           |   8 +
>  drivers/vfio/virqfd.c                         | 213 +++++++++++
>  include/linux/vfio.h                          |  27 ++
>  include/uapi/linux/vfio.h                     |   2 +
>  16 files changed, 1456 insertions(+), 236 deletions(-)
>  create mode 100644 drivers/vfio/platform/Kconfig
>  create mode 100644 drivers/vfio/platform/Makefile
>  create mode 100644 drivers/vfio/platform/vfio_amba.c
>  create mode 100644 drivers/vfio/platform/vfio_platform.c
>  create mode 100644 drivers/vfio/platform/vfio_platform_common.c
>  create mode 100644 drivers/vfio/platform/vfio_platform_irq.c
>  create mode 100644 drivers/vfio/platform/vfio_platform_private.h
>  create mode 100644 drivers/vfio/virqfd.c
>