From 5b32a53d6d057ab213abae33fc275be844051695 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 6 Apr 2021 13:46:42 +0100 Subject: [PATCH] KVM: arm64: Clarify vcpu reset behaviour Although the KVM_ARM_VCPU_INIT documentation mention that the registers are reset to their "initial values", it doesn't describe what these values are. Describe this state explicitly. Reviewed-by: Alexandru Elisei Acked-by: Will Deacon Signed-off-by: Marc Zyngier --- Documentation/virt/kvm/api.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 38e327d4b479..fedfe7104105 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -3115,6 +3115,18 @@ optional features it should have.  This will cause a reset of the cpu registers to their initial values.  If this is not called, KVM_RUN will return ENOEXEC for that vcpu. +The initial values are defined as: + - Processor state: + * AArch64: EL1h, D, A, I and F bits set. All other bits + are cleared. + * AArch32: SVC, A, I and F bits set. All other bits are + cleared. + - General Purpose registers, including PC and SP: set to 0 + - FPSIMD/NEON registers: set to 0 + - SVE registers: set to 0 + - System registers: Reset to their architecturally defined + values as for a warm reset to EL1 (resp. SVC) + Note that because some registers reflect machine topology, all vcpus should be created before this ioctl is invoked. -- 2.11.0