Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20200825...

Merge remote-tracking branch 'remotes/alistair/tags/pull-riscv-to-apply-20200825' into staging

This pull request first adds support for multi-socket NUMA RISC-V
machines. The Spike and Virt machines both support NUMA sockets.

This PR also updates the current experimental Hypervisor support to the
v0.6.1 spec.

# gpg: Signature made Tue 25 Aug 2020 19:47:41 BST
# gpg:                using RSA key F6C4AC46D4934868D3B8CE8F21E10D29DF977054
# gpg: Good signature from "Alistair Francis <alistair@alistair23.me>" [full]
# Primary key fingerprint: F6C4 AC46 D493 4868 D3B8  CE8F 21E1 0D29 DF97 7054

* remotes/alistair/tags/pull-riscv-to-apply-20200825:
  target/riscv: Support the Virtual Instruction fault
  target/riscv: Return the exception from invalid CSR accesses
  target/riscv: Support the v0.6 Hypervisor extension CRSs
  target/riscv: Only support little endian guests
  target/riscv: Only support a single VSXL length
  target/riscv: Update the CSRs to the v0.6 Hyp extension
  target/riscv: Update the Hypervisor trap return/entry
  target/riscv: Fix the interrupt cause code
  target/riscv: Convert MSTATUS MTL to GVA
  target/riscv: Don't allow guest to write to htinst
  target/riscv: Do two-stage lookups on hlv/hlvx/hsv instructions
  target/riscv: Allow generating hlv/hlvx/hsv instructions
  target/riscv: Allow setting a two-stage lookup in the virt status
  hw/riscv: virt: Allow creating multiple NUMA sockets
  hw/riscv: spike: Allow creating multiple NUMA sockets
  hw/riscv: Add helpers for RISC-V multi-socket NUMA machines
  hw/riscv: Allow creating multiple instances of PLIC
  hw/riscv: Allow creating multiple instances of CLINT

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>