Re: [PATCH v2 0/2] NVMe passthrough: Take into account host IOVA reserved regions

[Stefan Hajnoczi]

On Tue, Sep 29, 2020 at 10:55:48AM +0200, Eric Auger wrote:
> The current IOVA allocator allocates within the [0x10000, 1ULL << 39]
> window, without paying attention to the host IOVA reserved regions.
> This prevents NVMe passthtrough from working on ARM as the fixed
> IOVAs rapidly grow up to the MSI reserved region [0x8000000, 0x8100000]
> causing some VFIO MAP DMA failures. This series collects the usable
> IOVA regions using VFIO GET_INFO (this requires the host to support
> VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE) and rework the fixed and
> temporary IOVA allocators to avoid those latter.
> 
> For the time being we do not change the arbitrary min/max IOVAs.
> In theory they could be dynamically determined but the kernel
> currently fails to expose some HW limitations described in the ACPI
> tables (such as PCI root complex Device Memory Address Size Limit).
> See kernel thread related to "[RFC 0/3] iommu: Reserved regions for
> IOVAs beyond dma_mask and iommu aperture" for more details:
> https://lkml.org/lkml/2020/9/28/1102
> 
> Best Regards
> 
> Eric
> 
> This series can be found at:
> https://github.com/eauger/qemu/tree/nvme_resv_v2
> 
> This was tested on ARM only.
> 
> History:
> v1 -> v2:
> - remove "util/vfio-helpers: Dynamically compute the min/max IOVA" to
>   relax the kernel dependency
> - Fix cabapbility enumeration loop
> - set s->usable_iova_ranges=NULL to avoid double free
> - handle possible u64 wrap
> 
> Eric Auger (2):
>   util/vfio-helpers: Collect IOVA reserved regions
>   util/vfio-helpers: Rework the IOVA allocator to avoid IOVA reserved
>     regions
> 
>  util/vfio-helpers.c | 129 +++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 123 insertions(+), 6 deletions(-)
> 
> -- 
> 2.21.3
> 

Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block

Stefan

signature.asc
Description: PGP signature