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KVM: arm64: gic-v5: Communicate userspace-driveable PPIs via a UAPI

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GICv5 systems will likely not support the full set of PPIs. The
presence of any virtual PPI is tied to the presence of the physical
PPI. Therefore, the available PPIs will be limited by the physical
host. Userspace cannot drive any PPIs that are not implemented.

Moreover, it is not desirable to expose all PPIs to the guest in the
first place, even if they are supported in hardware. Some devices,
such as the arch timer, are implemented in KVM, and hence those PPIs
shouldn't be driven by userspace, either.

Provided a new UAPI:
  KVM_DEV_ARM_VGIC_GRP_CTRL => KVM_DEV_ARM_VGIC_USERPSPACE_PPIs

This allows userspace to query which PPIs it is able to drive via
KVM_IRQ_LINE.

Additionally, introduce a check in kvm_vm_ioctl_irq_line() to reject
any PPIs not in the userspace mask.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260319154937.3619520-40-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Sascha Bischoff
2026-03-19 15:59:50 +00:00
committed by Marc Zyngier
parent eb3c4d2c9a
commit d51c978b7d
7 changed files with 69 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

13
Documentation/virt/kvm/devices/arm-vgic-v5.rst
View File

@@ -25,6 +25,19 @@ Groups:
request the initialization of the VGIC, no additional parameter in
kvm_device_attr.addr. Must be called after all VCPUs have been created.
KVM_DEV_ARM_VGIC_USERPSPACE_PPIs
request the mask of userspace-drivable PPIs. Only a subset of the PPIs can
be directly driven from userspace with GICv5, and the returned mask
informs userspace of which it is allowed to drive via KVM_IRQ_LINE.
Userspace must allocate and point to __u64[2] of data in
kvm_device_attr.addr. When this call returns, the provided memory will be
populated with the userspace PPI mask. The lower __u64 contains the mask
for the lower 64 PPIS, with the remaining 64 being in the second __u64.
This is a read-only attribute, and cannot be set. Attempts to set it are
rejected.
Errors:
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