Re: [PATCH] skip virtio fs cache section to enable NIC pass through

[Dev Audsin <dev.devaqemu@gmail.com>]

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 virtio-fs with DAX is currently not compatible with NIC Pass through. VM
fails to boot when DAX  cache is enabled and SR-IOV VF is being attached.
This patch solves the problem. Hencem DAX cache and SR-IOV VF are be
attached together.

When a SR-IOV VF attaches to a qemu process, vfio will try to pin the
entire DAX Window but it is empty when the guest boots and will fail.
A method to make VFIO and DAX to work together is to make vfio skip DAX
cache.
Currently DAX cache need to be set to 0, for the SR-IOV VF to be attached
to Kata containers.
Enabling both SR-IOV VF and DAX work together will potentially improve
performance for workloads which are I/O and network intensive

On Mon, Apr 26, 2021 at 9:24 PM Dev Audsin <dev.devaqemu@gmail.com> wrote:

> Signed-off-by: Dev Audsin <dev.devaqemu@gmail.com>
> ---
>  hw/vfio/common.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index 6ff1daa763..3af70238bd 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -541,7 +541,8 @@ static int vfio_host_win_del(VFIOContainer *container,
> hwaddr min_iova,
>
>  static bool vfio_listener_skipped_section(MemoryRegionSection *section)
>  {
> -    return (!memory_region_is_ram(section->mr) &&
> +    return (!strcmp(memory_region_name(section->mr), "virtio-fs-cache"))
> ||
> +          (!memory_region_is_ram(section->mr) &&
>              !memory_region_is_iommu(section->mr)) ||
>             /*
>              * Sizing an enabled 64-bit BAR can cause spurious mappings to
> --
> 2.25.1
>

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