[PATCH] xen/riscv: dump CSRs on unexpected traps

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

Provide more context on the exception state when an unexpected
exception occurs by dumping various Supervisor, Virtual Supervisor
and Hypervisor CSRs.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/riscv/traps.c | 55 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/xen/arch/riscv/traps.c b/xen/arch/riscv/traps.c
index e9c967786312..d6c92588ea47 100644
--- a/xen/arch/riscv/traps.c
+++ b/xen/arch/riscv/traps.c
@@ -17,6 +17,10 @@
 #include <asm/traps.h>
 #include <asm/vsbi.h>
 
+#define print_csr(csr) do { \
+    printk("\t" #csr ": %#02lx\n", csr_read(csr)); \
+} while ( 0 )
+
 /*
  * Initialize the trap handling.
  *
@@ -99,12 +103,63 @@ static const char *decode_cause(unsigned long cause)
     return decode_trap_cause(cause);
 }
 
+static void dump_csrs(unsigned long cause)
+{
+    unsigned long hstatus;
+    bool gva;
+
+    printk("\nDumping CSRs...\n");
+
+    printk("Supervisor CSRs\n");
+    print_csr(CSR_STVEC);
+    print_csr(CSR_SATP);
+    print_csr(CSR_SEPC);
+
+    hstatus = csr_read(CSR_HSTATUS);
+    gva = !!(hstatus & HSTATUS_GVA);
+
+    printk("\tCSR_STVAL: %#02lx%s\n", csr_read(CSR_STVAL),
+           gva ? ", (guest virtual address)" : "");
+
+    printk("\tCSR_SCAUSE: %#02lx\n", cause);
+    printk("\t\tDescription: %s\n", decode_cause(cause));
+    print_csr(CSR_SSTATUS);
+
+    printk("\nVirtual Supervisor CSRs\n");
+    print_csr(CSR_VSTVEC);
+    print_csr(CSR_VSATP);
+    print_csr(CSR_VSEPC);
+    print_csr(CSR_VSTVAL);
+    cause = csr_read(CSR_VSCAUSE);
+    printk("\tCSR_VSCAUSE: %#02lx\n", cause);
+    printk("\t\tDescription: %s\n", decode_cause(cause));
+    print_csr(CSR_VSSTATUS);
+
+    printk("\nHypervisor CSRs\n");
+
+    print_csr(CSR_HSTATUS);
+    printk("\t\thstatus.VTSR=%d\n", !!(hstatus & HSTATUS_VTSR));
+    printk("\t\thstatus.VTVM=%d\n", !!(hstatus & HSTATUS_VTVM));
+    printk("\t\thstatus.HU=%d\n", !!(hstatus & HSTATUS_HU));
+    printk("\t\thstatus.SPVP=%d\n", !!(hstatus & HSTATUS_SPVP));
+    printk("\t\thstatus.SPV=%d\n", !!(hstatus & HSTATUS_SPV));
+    printk("\t\thstatus.GVA=%d\n", !!(hstatus & HSTATUS_GVA));
+    print_csr(CSR_HGATP);
+    print_csr(CSR_HTVAL);
+    print_csr(CSR_HTINST);
+    print_csr(CSR_HEDELEG);
+    print_csr(CSR_HIDELEG);
+    print_csr(CSR_HSTATEEN0);
+}
+
 static void do_unexpected_trap(const struct cpu_user_regs *regs)
 {
     unsigned long cause = csr_read(CSR_SCAUSE);
 
     printk("Unhandled exception: %s\n", decode_cause(cause));
 
+    dump_csrs(cause);
+
     die();
 }
 
-- 
2.52.0