From: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Date: Mon, 20 Mar 2023 16:10:34 +0000 (+0100)
Subject: xen/riscv: disable fpu
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=d1e67674591c262e7cedfcd42547a3f64caec251;p=people%2Froyger%2Fxen.git

xen/riscv: disable fpu

Disable FPU to detect illegal usage of floating point in kernel
space.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Bobby Eshleman <bobbyeshleman@gmail.com>
---

diff --git a/xen/arch/riscv/riscv64/head.S b/xen/arch/riscv/riscv64/head.S
index ffd95f9f89..52fa41c778 100644
--- a/xen/arch/riscv/riscv64/head.S
+++ b/xen/arch/riscv/riscv64/head.S
@@ -6,6 +6,13 @@ ENTRY(start)
         /* Mask all interrupts */
         csrw    CSR_SIE, zero
 
+        /*
+         * Disable FPU to detect illegal usage of
+         * floating point in kernel space
+         */
+        li      t0, SSTATUS_FS
+        csrc    CSR_SSTATUS, t0
+
         la      sp, cpu0_boot_stack
         li      t0, STACK_SIZE
         add     sp, sp, t0