[RFC PATCH 2/5] lib: sbi: Save core hypervisor state across domain switches

[whensun]

From: Theodorus Wensan Februanto <theodoruswensanfebruanto025 at gmail.com>

The domain context switch saves several supervisor CSRs but leaves
hypervisor trap, delegation, interrupt, and translation state shared
between domains.

Exchange core writable H-extension CSRs when H is available. Use a
64-bit exchange for henvcfg and check Smaia before accessing RV32
high-half AIA registers.

The domain protection reconfiguration performs SFENCE/HFENCE after
the CSR exchange.

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 | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/lib/sbi/sbi_domain_context.c b/lib/sbi/sbi_domain_context.c
index 26980658..caec5486 100644
--- a/lib/sbi/sbi_domain_context.c
+++ b/lib/sbi/sbi_domain_context.c
@@ -44,6 +44,22 @@ struct hart_context {
 	unsigned long sip;
 	/** Supervisor address translation and protection register */
 	unsigned long satp;
+
+	/** Hypervisor state */
+	unsigned long hstatus;
+	unsigned long hedeleg;
+	unsigned long hideleg;
+	unsigned long hie;
+	unsigned long hgeie;
+	u64 henvcfg;
+	unsigned long htval;
+	unsigned long htinst;
+	unsigned long hvip;
+	unsigned long hgatp;
+#if __riscv_xlen == 32
+	unsigned long hidelegh;
+	unsigned long hviph;
+#endif
 	/** Counter-enable register */
 	unsigned long scounteren;
 	/** Supervisor environment configuration register */
@@ -141,6 +157,26 @@ static int switch_to_next_domain_context(struct hart_context *ctx,
 	ctx->stval	= csr_swap(CSR_STVAL, dom_ctx->stval);
 	ctx->sip	= csr_swap(CSR_SIP, dom_ctx->sip);
 	ctx->satp	= csr_swap(CSR_SATP, dom_ctx->satp);
+
+	if (misa_extension('H')) {
+		ctx->hstatus = csr_swap(CSR_HSTATUS, dom_ctx->hstatus);
+		ctx->hedeleg = csr_swap(CSR_HEDELEG, dom_ctx->hedeleg);
+		ctx->hideleg = csr_swap(CSR_HIDELEG, dom_ctx->hideleg);
+		ctx->hie = csr_swap(CSR_HIE, dom_ctx->hie);
+		ctx->hgeie = csr_swap(CSR_HGEIE, dom_ctx->hgeie);
+		ctx->henvcfg = csr_swap64(CSR_HENVCFG, dom_ctx->henvcfg);
+		ctx->htval = csr_swap(CSR_HTVAL, dom_ctx->htval);
+		ctx->htinst = csr_swap(CSR_HTINST, dom_ctx->htinst);
+		ctx->hvip = csr_swap(CSR_HVIP, dom_ctx->hvip);
+		ctx->hgatp = csr_swap(CSR_HGATP, dom_ctx->hgatp);
+#if __riscv_xlen == 32
+		if (sbi_hart_has_extension(scratch, SBI_HART_EXT_SMAIA)) {
+			ctx->hidelegh = csr_swap(CSR_HIDELEGH,
+						dom_ctx->hidelegh);
+			ctx->hviph = csr_swap(CSR_HVIPH, dom_ctx->hviph);
+		}
+#endif
+	}
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_10)
 		ctx->scounteren = csr_swap(CSR_SCOUNTEREN, dom_ctx->scounteren);
 	if (sbi_hart_priv_version(scratch) >= SBI_HART_PRIV_VER_1_12)
-- 
2.43.0