Re: [PATCH v18 00/23] KVM: arm64: CCA: Add basic plumbing for Realms

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Mathieu Poirier <mathieu.poirier@linaro.org> writes:

> Hi Suzuki,
>
> On Tue, Sep 15, 2026 at 05:01:18PM +0100, Suzuki K Poulose wrote:

 [ ... 42 lines skipped ... ] 

>> 
>> [0] Arm CCA KVM Support v16 : https://lore.kernel.org/all/20260803134403.80630-1-steven.price@arm.com
>> [1] Linux firmware RMI https://lore.kernel.org/all/20260912083611.2513845-1-suzuki.poulose@arm.com
>> [2] Linux GPF Host https://lore.kernel.org/all/20260913070459.2547407-1-suzuki.poulose@arm.com
>> [3] https://git.gitlab.arm.com/linux-arm/linux-cca/ cca/cca-host/kvm-v18/integration
>> [4] https://support.arm.com/documentation/den0137/2-0bet3/
>
> When testing on the FVP model with the above baselines, I get the following
> error messagaes in a loop, preventing the system from reaching the command line:
>
> [    3.112577] Freeing unused kernel memory: 3520K
> [    3.115398] Run /sbin/init as init process
> [    3.142926] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.150111] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.177190] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.197194] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.217188] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.237194] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.257181] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.277189] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.297193] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    3.317188] virtio-pci 0000:00:02.0: swiotlb buffer is full (sz: 4096 bytes),
> total 512 (slots), used 511 (slots)
> [    8.157185] swiotlb_tbl_map_single: 241 callbacks suppressed
>
> I get the same result with v17.  Have you seen this before?  Perhaps a kernel
> option that needs to be adjusted?
>

This is due to a change in the swiotlb setup.

https://lore.kernel.org/all/yq5azeyxyfol.fsf@kernel.org

You can increase the swiotlb size using the swiotlb= kernel command-line
option. I also have a patch series in progress to address this issue:

https://lore.kernel.org/all/20260921063628.362078-1-aneesh.kumar@kernel.org

-aneesh