[PATCH] lib: sbi: Preserve vl and vtype during domain switches

[whensun]

Save vl and vtype as part of the Vector domain context.

Restore both CSRs using vsetvl after restoring the Vector register
file. Restore vstart after vsetvl because Vector configuration
instructions reset vstart.

Link: https://github.com/riscv-software-src/opensbi/issues/434
Signed-off-by: whensun <theodoruswensanfebruanto025 at gmail.com>
---
 include/sbi/sbi_vector.h |  2 ++
 lib/sbi/sbi_vector.c     | 11 +++++++++++
 2 files changed, 13 insertions(+)

diff --git a/include/sbi/sbi_vector.h b/include/sbi/sbi_vector.h
index c14f3174..480f9ac3 100644
--- a/include/sbi/sbi_vector.h
+++ b/include/sbi/sbi_vector.h
@@ -15,6 +15,8 @@
 struct sbi_vector_context {
 	unsigned long vcsr;
 	unsigned long vstart;
+	unsigned long vl;
+	unsigned long vtype;
 
 	/* size depends on VLEN */
 	uint8_t vregs[];
diff --git a/lib/sbi/sbi_vector.c b/lib/sbi/sbi_vector.c
index 1f9e01cf..53c2e5a7 100644
--- a/lib/sbi/sbi_vector.c
+++ b/lib/sbi/sbi_vector.c
@@ -33,6 +33,8 @@ void sbi_vector_save(struct sbi_vector_context *dst)
 	/* Step 2: Save CSRs */
 	dst->vcsr = csr_read(vcsr);
 	dst->vstart = csr_read(vstart);
+	dst->vl = csr_read(vl);
+	dst->vtype = csr_read(vtype);
 
 	/* Step 3: Save vector registers */
 #define SAVE_VREG(i)							\
@@ -86,6 +88,15 @@ void sbi_vector_restore(const struct sbi_vector_context *src)
 
 	/* Step 3: Restore CSR's last */
 	/* Restore CSRs first */
+	asm volatile(
+		".option push\n\t"
+		".option arch, +v\n\t"
+		"vsetvl zero, %0, %1\n\t"
+		".option pop\n\t"
+		:
+		: "r"(src->vl), "r"(src->vtype)
+		: "memory");
+
 	csr_write(vcsr,   src->vcsr);
 	csr_write(vstart, src->vstart);
 
-- 
2.43.0