KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst

KVM/arm64 makes use of the SMCCC "Vendor Specific Hypervisor Service
Call Range" to expose KVM-specific hypercalls to guests in a
discoverable and extensible fashion.

Document the existence of this interface and the discovery hypercall.

Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-28-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

KVM: arm64: Rename firmware pseudo-register documentation file

In preparation for describing the guest view of KVM/arm64 hypercalls in
hypercalls.rst, move the existing contents of the file concerning the
firmware pseudo-registers elsewhere.

Cc: Raghavendra Rao Ananta <rananta@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240423150538.2103045-27-tabba@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

KVM: arm64: Document vCPU feature selection UAPIs

KVM/arm64 has a couple schemes for handling vCPU feature selection now,
which is a lot to put on userspace. Add some documentation about how
these interact and provide some recommendations for how to use the
writable ID register scheme.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20231003230408.3405722-11-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Documentation: Fix index.rst after psci.rst renaming

Fix the TOC in index.rst after psci.rst has been renamed to
hypercalls.rst.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Link: https://lore.kernel.org/r/20220504205627.18f46380@canb.auug.org.au

KVM: arm64: Add support for the KVM PTP service

Implement the hypervisor side of the KVM PTP interface.

The service offers wall time and cycle count from host to guest.
The caller must specify whether they want the host's view of
either the virtual or physical counter.

Signed-off-by: Jianyong Wu <jianyong.wu@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201209060932.212364-7-jianyong.wu@arm.com

docs: kvm: arm/psci.txt: convert to ReST

- Add a title for the document;
- Adjust whitespaces for it to be properly formatted after
parsed.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs: kvm: convert arm/hyp-abi.txt to ReST

- Add proper markups for titles;
- Adjust whitespaces and blank lines to match ReST
needs;
- Mark literal blocks as such.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

docs: kvm: add arm/pvtime.rst to index.rst

Add this file to a new kvm/arm index.rst, in order for it to
be shown as part of the virt book.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>