[PATCH v2 17/39] xen/riscv: decouple INSN_PSEUDO_VS_* from the hypervisor's XLEN

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

htinst reports a pseudoinstruction when a guest page fault is taken on an
implicit memory access done for VS-stage address translation. Four such
values are defined, differing in the access type (read or write) and in the
access width: 4 bytes (0x2000/0x2020) or 8 bytes (0x3000/0x3020).

That width is the width of a VS-stage PTE, i.e. it follows the guest's
paging mode (4 bytes for Sv32, 8 bytes for Sv39 and wider) and has nothing
to do with the XLEN Xen itself is built for. Selecting just one pair with
where a guest running with VSXL=32 and Sv32 in vsatp produces the 4-byte
forms. Such an htinst would not be recognized as a pseudoinstruction and the
fault would be mistaken for an ordinary MMIO trap: Xen would fetch and
decode whatever instruction sepc happens to point at (unrelated to the
access which faulted) and emulate it against a guest physical address
derived from htval, which for an implicit access holds the address of a
VS-stage PTE rather than of any access the guest performed.

Define all four values unconditionally instead, named after the access width
they encode rather than after the build's XLEN. On RV32 the 8-byte forms
simply never occur, so recognizing them costs nothing.

Dropping the ladder loses no build-time coverage: a build for an XLEN other
than 32 or 64 already fails on the equivalent ladders in asm/asm.h and
asm/config.h, so no replacement #error is needed here. Adding one keyed on
CONFIG_RISCV_* would in any case re-introduce exactly the conflation this
patch removes.

This diverges from the imported version of riscv_encoding.h.

No functional change: the values have no user yet.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
Changes in v2:
 - New patch.
---
---
 xen/arch/riscv/include/asm/riscv_encoding.h | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/xen/arch/riscv/include/asm/riscv_encoding.h 
b/xen/arch/riscv/include/asm/riscv_encoding.h
index c63e5e304691..2d2e7e11b3ef 100644
--- a/xen/arch/riscv/include/asm/riscv_encoding.h
+++ b/xen/arch/riscv/include/asm/riscv_encoding.h
@@ -839,25 +839,17 @@
 #define INSN_MASK_FENCE_TSO            0xffffffff
 #define INSN_MATCH_FENCE_TSO           0x8330000f
 
-#if __riscv_xlen == 64
-
 /* 64-bit read for VS-stage address translation (RV64) */
-#define INSN_PSEUDO_VS_LOAD            0x00003000
+#define INSN_PSEUDO_VS_LOAD64          0x00003000
 
 /* 64-bit write for VS-stage address translation (RV64) */
-#define INSN_PSEUDO_VS_STORE   0x00003020
-
-#elif __riscv_xlen == 32
+#define INSN_PSEUDO_VS_STORE64         0x00003020
 
 /* 32-bit read for VS-stage address translation (RV32) */
-#define INSN_PSEUDO_VS_LOAD            0x00002000
+#define INSN_PSEUDO_VS_LOAD32          0x00002000
 
 /* 32-bit write for VS-stage address translation (RV32) */
-#define INSN_PSEUDO_VS_STORE   0x00002020
-
-#else
-#error "Unexpected __riscv_xlen"
-#endif
+#define INSN_PSEUDO_VS_STORE32         0x00002020
 
 #define INSN_16BIT_MASK                        0x3
 #define INSN_32BIT_MASK                        0x1c
-- 
2.55.0