From d766d87cf4a0a415a45bbb8fc2e3a4cc1995654d Mon Sep 17 00:00:00 2001 From: Oliver Upton Date: Wed, 26 Feb 2025 10:31:24 -0800 Subject: [PATCH] KVM: arm64: Document ordering requirements for irqbypass One of the not-so-obvious requirements for restoring a VM is ensuring that the vITS has been restored _before_ creating any irqbypass mappings. This is because KVM needs to get the guest translation for MSIs to correctly assemble the vLPI mapping getting installed in the physical ITS. Document the restore ordering requirements necessary for GICv4 vLPI injection to work. Acked-by: Marc Zyngier Link: https://lore.kernel.org/r/20250226183124.82094-5-oliver.upton@linux.dev Signed-off-by: Oliver Upton --- Documentation/virt/kvm/devices/arm-vgic-its.rst | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/Documentation/virt/kvm/devices/arm-vgic-its.rst b/Documentation/virt/kvm/devices/arm-vgic-its.rst index e053124f77c48..0f971f83205a9 100644 --- a/Documentation/virt/kvm/devices/arm-vgic-its.rst +++ b/Documentation/virt/kvm/devices/arm-vgic-its.rst @@ -126,7 +126,8 @@ KVM_DEV_ARM_VGIC_GRP_ITS_REGS ITS Restore Sequence: --------------------- -The following ordering must be followed when restoring the GIC and the ITS: +The following ordering must be followed when restoring the GIC, ITS, and +KVM_IRQFD assignments: a) restore all guest memory and create vcpus b) restore all redistributors @@ -139,6 +140,8 @@ d) restore the ITS in the following order: 3. Load the ITS table data (KVM_DEV_ARM_ITS_RESTORE_TABLES) 4. Restore GITS_CTLR +e) restore KVM_IRQFD assignments for MSIs + Then vcpus can be started. ITS Table ABI REV0: -- 2.47.3