[PATCH v2 16/36] KVM: arm64: gic-v5: Implement direct injection of PPIs

[Jonathan Cameron]

On Fri, 19 Dec 2025 15:52:41 +0000
Sascha Bischoff <Sascha.Bischoff at arm.com> wrote:

> GICv5 is able to directly inject PPI pending state into a guest using
> a mechanism called DVI whereby the pending bit for a paticular PPI is
> driven directly by the physically-connected hardware. This mechanism
> itself doesn't allow for any ID translation, so the host interrupt is
> directly mapped into a guest with the same interrupt ID.
> 
> When mapping a virtual interrupt to a physical interrupt via
> kvm_vgic_map_irq for a GICv5 guest, check if the interrupt itself is a
> PPI or not. If it is, and the host's interrupt ID matches that used
> for the guest DVI is enabled, and the interrupt itself is marked as
> directly_injected.
> 
> When the interrupt is unmapped again, this process is reversed, and
> DVI is disabled for the interrupt again.
> 
> Note: the expectation is that a directly injected PPI is disabled on
> the host while the guest state is loaded. The reason is that although
> DVI is enabled to drive the guest's pending state directly, the host
> pending state also remains driven. In order to avoid the same PPI
> firing on both the host and the guest, the host's interrupt must be
> disabled (masked). This is left up to the code that owns the device
> generating the PPI as this needs to be handled on a per-VM basis. One
> VM might use DVI, while another might not, in which case the physical
> PPI should be enabled for the latter.
> 
> Co-authored-by: Timothy Hayes <timothy.hayes at arm.com>
> Signed-off-by: Timothy Hayes <timothy.hayes at arm.com>
> Signed-off-by: Sascha Bischoff <sascha.bischoff at arm.com>

Reviewed-by: Jonathan Cameron <jonathan.cameron at huawei.com>