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Date: Thu, 14 Aug 2025 17:07:35 +0100
From: Cristian Marussi <cristian.marussi@arm.com>
To: Paolo Abeni <pabeni@redhat.com>
Cc: kvm@vger.kernel.org, Cristian Marussi <cristian.marussi@arm.com>,
	Will Deacon <will@kernel.org>
Subject: Re: [PATCH kvmtool] virtio/pci: explicit zero unknown devices
 features
Message-ID: <aJ4Jx784CjBgY1pz@pluto>
References: <ed62443b8fd3fef87bd313a54f821cf363f647a5.1755185758.git.pabeni@redhat.com>
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In-Reply-To: <ed62443b8fd3fef87bd313a54f821cf363f647a5.1755185758.git.pabeni@redhat.com>

On Thu, Aug 14, 2025 at 05:37:02PM +0200, Paolo Abeni wrote:
> The linux kernel implementation for the virtio_net driver recently
> gained support for virtio features above the 64th bit.
> 

Hi,

> It relies on the hypervisor to clear the features data for unknown /
> unsupported features range.
> 
> The current pci-modern implementation, in such scenario, leaves the
> data memory untouched, which causes the guest kernel assuming "random"
> features are supported (and possibly leaks host memory contents).
> 
> Explicitly clear the features data for unsupported range.
> 

This patch definitely solves for me the virtio networking issue reported at:

https://lore.kernel.org/virtualization/c25f924f-a66b-47cc-819d-5ed241a4bac6@redhat.com/T/#t

Tested on an arm64 Host (v6.14.8) with a v6.17-rc1 Guest.

Thanks !

Tested-by: Cristian Marussi <cristian.marussi@arm.com>

Thanks,
Cristian