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CSR Bit Fields

RISC-V vsireg CSR Register

Address 0x251Privilege Hypervisor direct / VS aliasAccess HRW / current XLEN, not VSXLENHypervisor and virtualization CSRs

vsireg is a VS indirect CSR data window selected by vsiselect.

Related Search Terms
vsireg CSRvsireg 0x251VS indirect CSRvsiselect selectorSmcsrind
Bit Overview
bit 3 = only bit 3; bits 12..11 = bits 12 down to 11
MSBLSB
DATA63:0RW
Field Map

Understand vsireg By Bit Fields

1 key fields
XLEN-1:0

DATA

RW

Data window for the VS indirect CSR selected by vsiselect.

DATA (bits XLEN-1:0) — Data window for the VS indirect CSR selected by vsiselect.

What This Field Controls

  • - Data window for the VS indirect CSR selected by vsiselect.

Common Values

This field is better understood together with surrounding context than as a fixed memorized enumeration.

↗Open Official Manual
Official Basis & Search Notes

vsireg is a VS indirect-CSR access CSR. The separate CSR address is for M/HS-side management; when V=1, guest access to the corresponding supervisor CSR is substituted with VS state unless an extension specifies otherwise.

vsireg address, access class, and width are checked against the official CSR tables: 0x251, HRW, current XLEN, not VSXLEN.
vsiselect supports at least selector range 0..0xFFF; custom selectors use the space with the most-significant bit set.
Direct VS/VU access to vsiselect/vsireg* raises a virtual-instruction exception; a guest normally uses the siselect/sireg* aliases.
When writing, modify only officially defined fields; handle WARL, WLRL, WPRI, and reserved fields according to the official specification and implementation behavior.
RISC-V Privileged Architecture Manual - CSR tableRISC-V Privileged Architecture Manual - Hypervisor extensionRISC-V Smcsrind/Sscsrind indirect CSR extension

What To Check First When Reading This CSR

  • - vsireg's separate CSR address is in the official HRW access class; a VS/VU guest normally reaches VS state through the corresponding supervisor CSR alias.
  • - Before reading it, confirm that the defining extension such as H, AIA, Sstc, Smstateen, or Smcsrind is implemented.

Risk Checks Before Writing

  • - When writing vsireg, modify only officially defined target fields and preserve WPRI, reserved, and unchanged fields.

Put It Back Into A Real Flow

1

Write or confirm the vsiselect selector first.

2

Use the matching vsireg* data window for indirectly selected state defined by an official extension.

3

An unimplemented selector may raise an exception or have unspecified behavior; do not assume ordinary memory-window semantics.

FAQ

What selector range does vsiselect support?

The official Smcsrind/Sscsrind rules require at least 0..0xFFF; values with the most-significant bit set are for custom use.

Can VS-mode directly access vsireg?

Direct VS/VU access to vsiselect or vsireg* raises a virtual-instruction exception; a guest should use the siselect/sireg* aliases.