Re: [PATCH for-4.19] x86/pvh: declare PVH dom0 supported with caveats

["Oleksii K." <oleksii.kurochko@xxxxxxxxx>]

On Fri, 2024-06-07 at 12:03 +0200, Roger Pau Monne wrote:
> PVH dom0 is functionally very similar to PVH domU except for the
> domain
> builder and the added set of hypercalls available to it.
> 
> The main concern with declaring it "Supported" is the lack of some
> features
> when compared to classic PV dom0, hence switch it's status to
> supported with
> caveats.  List the known missing features, there might be more
> features missing
> or not working as expected apart from the ones listed.
> 
> Note there's some (limited) PVH dom0 testing on both osstest and
> gitlab.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

~ Oleksii

> ---
> Hopefully this will attract more testing an resources to PVH dom0 in
> order to
> try to finish the missing features.
> ---
>  CHANGELOG.md |  1 +
>  SUPPORT.md   | 15 ++++++++++++++-
>  2 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/CHANGELOG.md b/CHANGELOG.md
> index 201478aa1c0e..1778419cae64 100644
> --- a/CHANGELOG.md
> +++ b/CHANGELOG.md
> @@ -14,6 +14,7 @@ The format is based on [Keep a
> Changelog](https://keepachangelog.com/en/1.0.0/)
>     - HVM PIRQs are disabled by default.
>     - Reduce IOMMU setup time for hardware domain.
>     - Allow HVM/PVH domains to map foreign pages.
> +   - Declare PVH dom0 supported with caveats.
>   - xl/libxl configures vkb=[] for HVM domains with priority over
> vkb_device.
>   - Increase the maximum number of CPUs Xen can be built for from
> 4095 to
>     16383.
> diff --git a/SUPPORT.md b/SUPPORT.md
> index d5d60c62ec11..711aacf34662 100644
> --- a/SUPPORT.md
> +++ b/SUPPORT.md
> @@ -161,7 +161,20 @@ Requires hardware virtualisation support (Intel
> VMX / AMD SVM).
>  Dom0 support requires an IOMMU (Intel VT-d / AMD IOMMU).
>  
>      Status, domU: Supported
> -    Status, dom0: Experimental
> +    Status, dom0: Supported, with caveats
> +
> +PVH dom0 hasn't received the same test coverage as PV dom0, so it
> can exhibit
> +unexpected behavior or issues on some hardware.
> +
> +At least the following features are missing on a PVH dom0:
> +
> +  * PCI SR-IOV and Resizable BARs.
> +
> +  * Native NMI forwarding (nmi=dom0 command line option).
> +
> +  * MCE handling.
> +
> +  * PCI Passthrough to any kind of domUs.
>  
>  ### ARM
>