Add hypervisor extension

This PR implements v0.6.1 of the RISC-V Hypervisor Extension.

The implementation was inspired by José Martins' and colleagues' work
described in [1].  Much of the microarchitecture and essentially all of
the code is new, but their implementation served as our baseline.
We thank them for trailblazing hypervisor support in rocket-chip.

Note that this PR only includes the mechanisms to virtualize the hart
itself.  Virtualized interrupt controllers, IOMMUs, etc. are future work.
Lots of future work.

Note also that some features are (legally) not implemented.  Currently,
misa.H is not writable, something we may or may not choose to fix.
The mtval2 htval, mtinst, and htinst CSRs are hardwired to 0, placing
additional onus on hypervisor software.  We think it's likely we'll
eventually implement these CSRs less trivially, at least in some cases.

[1] "A First Look at RISC-V Virtualization from an Embedded Systems Perspective", https://arxiv.org/abs/2103.14951

src/main/resources/vsrc/RoccBlackBox.v

@@ -32,9 +32,15 @@ module RoccBlackBox
     input rocc_cmd_bits_status_wfi,
     input [31:0] rocc_cmd_bits_status_isa,
     input [PRV_SZ-1:0] rocc_cmd_bits_status_dprv,
+    input rocc_cmd_bits_status_dv,
     input [PRV_SZ-1:0] rocc_cmd_bits_status_prv,
+    input rocc_cmd_bits_status_v,
     input rocc_cmd_bits_status_sd,
-    input [26:0] rocc_cmd_bits_status_zero2,
+    input [22:0] rocc_cmd_bits_status_zero2,
+    input rocc_cmd_bits_status_mpv,
+    input rocc_cmd_bits_status_gva,
+    input rocc_cmd_bits_status_mbe,
+    input rocc_cmd_bits_status_sbe,
     input [1:0] rocc_cmd_bits_status_sxl,
     input [1:0] rocc_cmd_bits_status_uxl,
     input rocc_cmd_bits_status_sd_rv32,
@@ -51,7 +57,7 @@ module RoccBlackBox
     input [1:0] rocc_cmd_bits_status_mpp,
     input [0:0] rocc_cmd_bits_status_spp,
     input rocc_cmd_bits_status_mpie,
-    input rocc_cmd_bits_status_hpie,
+    input rocc_cmd_bits_status_ube,
     input rocc_cmd_bits_status_spie,
     input rocc_cmd_bits_status_upie,
     input rocc_cmd_bits_status_mie,
@@ -73,6 +79,7 @@ module RoccBlackBox
     output rocc_mem_req_bits_no_alloc,
     output rocc_mem_req_bits_no_xcpt,
     output [1:0] rocc_mem_req_bits_dprv,
+    output rocc_mem_req_bits_dv,
     output [coreDataBits-1:0] rocc_mem_req_bits_data,
     output [coreDataBytes-1:0] rocc_mem_req_bits_mask,
     output rocc_mem_s1_kill,
@@ -97,11 +104,14 @@ module RoccBlackBox
     input [coreDataBits-1:0] rocc_mem_resp_bits_data_raw,
     input [coreDataBits-1:0] rocc_mem_resp_bits_store_data,
     input [1:0] rocc_mem_resp_bits_dprv,
+    input rocc_mem_resp_bits_dv,
     input rocc_mem_replay_next,
     input rocc_mem_s2_xcpt_ma_ld,
     input rocc_mem_s2_xcpt_ma_st,
     input rocc_mem_s2_xcpt_pf_ld,
     input rocc_mem_s2_xcpt_pf_st,
+    input rocc_mem_s2_xcpt_gf_ld,
+    input rocc_mem_s2_xcpt_gf_st,
     input rocc_mem_s2_xcpt_ae_ld,
     input rocc_mem_s2_xcpt_ae_st,
     input rocc_mem_ordered,