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 <alexandru.elisei@arm.com>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>

diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 38e327d..fedfe71 100644 (file)
--- 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.