[Xen-devel] [PATCH v2 11/19] xen: arm: Annotate handlers for CPTR_EL2.Tx

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

Also expand on the comment when writing CPTR_EL2 to mention that most
of the bits we are setting are RES1 on arm64 anyway.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v2: s/PCTR/CPTR/
    Expand the comment when writing to CPTR_EL2
---
 xen/arch/arm/traps.c |   23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index afa8a95..a2bae51 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -110,8 +110,13 @@ void __cpuinit init_traps(void)
     /* Trap CP15 c15 used for implementation defined registers */
     WRITE_SYSREG(HSTR_T(15), HSTR_EL2);
 
-    /* Trap all coprocessor registers (0-13) except cp10 and cp11 for VFP
-     * /!\ All processors except cp10 and cp11 cannot be used in Xen
+    /* Trap all coprocessor registers (0-13) except cp10 and
+     * cp11 for VFP.
+     *
+     * /!\ All coprocessors except cp10 and cp11 cannot be used in Xen.
+     *
+     * On ARM64 the TCPx bits which we set here (0..9,12,13) are all
+     * RES1, i.e. they would trap whether we did this write or not.
      */
     WRITE_SYSREG((HCPTR_CP_MASK & ~(HCPTR_CP(10) | HCPTR_CP(11))) | HCPTR_TTA,
                  CPTR_EL2);
@@ -1710,6 +1715,11 @@ static void do_cp15_32(struct cpu_user_regs *regs,
      * ARMv7 (DDI 0406C.b): B1.14.3
      * ARMv8 (DDI 0487A.d): D1-1501 Table D1-43
      *
+     * CPTR_EL2.T{0..9,12..13}
+     *
+     * ARMv7 (DDI 0406C.b): B1.14.12
+     * ARMv8 (DDI 0487A.d): N/A
+     *
      * And all other unknown registers.
      */
     default:
@@ -1741,6 +1751,15 @@ static void do_cp15_64(struct cpu_user_regs *regs,
         if ( !vtimer_emulate(regs, hsr) )
             return inject_undef_exception(regs, hsr);
         break;
+
+    /*
+     * CPTR_EL2.T{0..9,12..13}
+     *
+     * ARMv7 (DDI 0406C.b): B1.14.12
+     * ARMv8 (DDI 0487A.d): N/A
+     *
+     * And all other unknown registers.
+     */
     default:
         {
             const struct hsr_cp64 cp64 = hsr.cp64;
-- 
1.7.10.4


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