From 6fa3555cc501ab1dfb034061e991e065e2e54253 Mon Sep 17 00:00:00 2001
From: Andrew Waterman <andrew@sifive.com>
Date: Mon, 13 Jan 2020 12:14:04 -0800
Subject: Enable vector unit if present (continuation of
 77a5df569451571d608650a34183d53df99790ec)

---
 machine/encoding.h | 1 +
 machine/minit.c    | 8 ++++++--
 pk/pk.c            | 2 +-
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/machine/encoding.h b/machine/encoding.h
index 20c44b9..1953f56 100644
--- a/machine/encoding.h
+++ b/machine/encoding.h
@@ -33,6 +33,7 @@
 #define SSTATUS_UPIE        0x00000010
 #define SSTATUS_SPIE        0x00000020
 #define SSTATUS_SPP         0x00000100
+#define SSTATUS_VS          0x01800000
 #define SSTATUS_FS          0x00006000
 #define SSTATUS_XS          0x00018000
 #define SSTATUS_SUM         0x00040000
diff --git a/machine/minit.c b/machine/minit.c
index 8c98e2b..a1befd1 100644
--- a/machine/minit.c
+++ b/machine/minit.c
@@ -23,13 +23,17 @@ void* kernel_end;
 
 static void mstatus_init()
 {
+  uintptr_t mstatus = 0;
+
   // Enable FPU
   if (supports_extension('F'))
-    write_csr(mstatus, MSTATUS_FS);
+    mstatus |= MSTATUS_FS;
 
   // Enable vector extension
   if (supports_extension('V'))
-    write_csr(mstatus, MSTATUS_VS);
+    mstatus |= MSTATUS_VS;
+
+  write_csr(mstatus, mstatus);
 
   // Enable user/supervisor use of perf counters
   if (supports_extension('S'))
diff --git a/pk/pk.c b/pk/pk.c
index a2be365..bce11a5 100644
--- a/pk/pk.c
+++ b/pk/pk.c
@@ -187,7 +187,7 @@ void boot_loader(uintptr_t dtb)
   write_csr(stvec, &trap_entry);
   write_csr(sscratch, 0);
   write_csr(sie, 0);
-  set_csr(sstatus, SSTATUS_SUM | SSTATUS_FS);
+  set_csr(sstatus, SSTATUS_SUM | SSTATUS_FS | SSTATUS_VS);
 
   file_init();
   enter_supervisor_mode(rest_of_boot_loader, pk_vm_init(), 0);
-- 
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