riscv: use mret to invoke M-mode payload and disable interrupts

Fixes a logic error that sets MPIE, but didn't use mret to return to the payload.
This left MIE set to an undefined value.

Now all modes are handled the same way:
- Trap vector base address point to the payload
- Disable Interrupt
- Return to payload using mret

TEST=Run an M-mode payload

Change-Id: Iaab595f916949c57104ec00f8b06ea047fe76bba
Signed-off-by: Xiang Wang <wxjstz@126.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33462
Reviewed-by: Philipp Hug <philipp@hug.cx>
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Patrick Rudolph <siro@das-labor.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 20 insertions, 5 deletions

diff --git a/src/arch/riscv/payload.c b/src/arch/riscv/payload.c
index f3ed5a44a6..903e8a6ab6 100644
--- a/src/arch/riscv/payload.c
+++ b/src/arch/riscv/payload.c
@@ -19,23 +19,38 @@
 #include <arch/boot.h>
 #include <arch/encoding.h>
 #include <console/console.h>
+#include <vm.h>
 
 void run_payload(struct prog *prog, void *fdt, int payload_mode)
 {
 	void (*doit)(int hart_id, void *fdt) = prog_entry(prog);
 	int hart_id = read_csr(mhartid);
 	uintptr_t status = read_csr(mstatus);
-	status &= ~MSTATUS_MPIE;
-	status &= ~MSTATUS_MPP;
+	status = INSERT_FIELD(status, MSTATUS_MPIE, 0);
 	switch (payload_mode) {
 	case RISCV_PAYLOAD_MODE_U:
+		status = INSERT_FIELD(status, MSTATUS_MPP, PRV_U);
+		/* Trap vector base address point to the payload */
+		write_csr(utvec, doit);
+		/* disable U-Mode interrupt */
+		write_csr(uie, 0);
 		break;
 	case RISCV_PAYLOAD_MODE_S:
-		status |= MSTATUS_SPP;
+		status = INSERT_FIELD(status, MSTATUS_MPP, PRV_S);
+		/* Trap vector base address point to the payload */
+		write_csr(stvec, doit);
+		/* disable S-Mode interrupt */
+		write_csr(sie, 0);
+		/* disable MMU */
+		write_csr(satp, 0);
 		break;
 	case RISCV_PAYLOAD_MODE_M:
-		doit(hart_id, fdt);
-		return;
+		status = INSERT_FIELD(status, MSTATUS_MPP, PRV_M);
+		/* Trap vector base address point to the payload */
+		write_csr(mtvec, doit);
+		/* disable M-Mode interrupt */
+		write_csr(mie, 0);
+		break;
 	default:
 		die("wrong privilege level for payload");
 		break;