Commit 5b32a53d authored by Marc Zyngier's avatar Marc Zyngier
Browse files

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: default avatarAlexandru Elisei <alexandru.elisei@arm.com>
Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 1a219e08

Documentation/virt/kvm/api.rst

+12 −0
Original line number Diff line number Diff line
@@ -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.