[RFC PATCH v2 2/8] lib: sbi: Preserve optional H-extension state across domain switches

[Theodorus Wensan Februanto]

Preserve hypervisor interrupt enable state provided by Smaia and
hypervisor state-enable CSRs provided by Smstateen.

Use extension checks so systems without these CSRs are unaffected.
The 64-bit helper preserves the corresponding high-half CSRs on RV32.

Link: https://github.com/riscv-software-src/opensbi/issues/433
Signed-off-by: Theodorus Wensan Februanto <theodoruswensanfebruanto025 at gmail.com>
---
 lib/sbi/sbi_domain_context.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/lib/sbi/sbi_domain_context.c b/lib/sbi/sbi_domain_context.c
index 4bafda5b..79419edc 100644
--- a/lib/sbi/sbi_domain_context.c
+++ b/lib/sbi/sbi_domain_context.c
@@ -32,6 +32,9 @@ struct hart_context_hext {
 	unsigned long htinst;
 	unsigned long hvip;
 	unsigned long hgatp;
+	/** Optional hypervisor state */
+	u64 hvien;
+	u64 hstateen[4];
 #if __riscv_xlen == 32
 	unsigned long hidelegh;
 	unsigned long hviph;
@@ -208,6 +211,19 @@ static int switch_to_next_domain_context(struct hart_context *ctx,
 			ctx->hext.hviph = csr_swap(CSR_HVIPH, dom_ctx->hext.hviph);
 		}
 #endif
+		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMAIA))
+			ctx->hext.hvien = csr_swap64(CSR_HVIEN, dom_ctx->hext.hvien);
+
+		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMSTATEEN)) {
+			ctx->hext.hstateen[0] = csr_swap64(CSR_HSTATEEN0,
+						dom_ctx->hext.hstateen[0]);
+			ctx->hext.hstateen[1] = csr_swap64(CSR_HSTATEEN1,
+						dom_ctx->hext.hstateen[1]);
+			ctx->hext.hstateen[2] = csr_swap64(CSR_HSTATEEN2,
+						dom_ctx->hext.hstateen[2]);
+			ctx->hext.hstateen[3] = csr_swap64(CSR_HSTATEEN3,
+						dom_ctx->hext.hstateen[3]);
+		}
 	}
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10)
 		ctx->scounteren = csr_swap(CSR_SCOUNTEREN, dom_ctx->scounteren);
-- 
2.43.0