[Xen-devel] [PATCH v8 2/6] arm: filter SMC exceptions with failed condition checks

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>]

In AArch32 state, the ARMv8-A architecture permits, but does not require,
this trap to apply to conditional SMC instructions that fail their condition
code check, in the same way as with traps on other conditional instructions.

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
Suggested-by: Julien Grall <julien.grall@xxxxxxx>
---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
---
 xen/arch/arm/traps.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index 44926ca..627e8c9 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -2507,6 +2507,17 @@ bad_data_abort:
     inject_dabt_exception(regs, info.gva, hsr.len);
 }
 
+static void do_trap_smc(struct cpu_user_regs *regs, const union hsr hsr)
+{
+    if ( !check_conditional_instr(regs, hsr) )
+    {
+        advance_pc(regs, hsr);
+        return;
+    }
+
+    inject_undef_exception(regs, hsr);
+}
+
 static void enter_hypervisor_head(struct cpu_user_regs *regs)
 {
     if ( guest_mode(regs) )
@@ -2582,7 +2593,7 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
*regs)
          */
         GUEST_BUG_ON(!psr_mode_is_32bit(regs->cpsr));
         perfc_incr(trap_smc32);
-        inject_undef32_exception(regs);
+        do_trap_smc(regs, hsr);
         break;
     case HSR_EC_HVC32:
         GUEST_BUG_ON(!psr_mode_is_32bit(regs->cpsr));
@@ -2615,7 +2626,7 @@ asmlinkage void do_trap_hypervisor(struct cpu_user_regs 
*regs)
          */
         GUEST_BUG_ON(psr_mode_is_32bit(regs->cpsr));
         perfc_incr(trap_smc64);
-        inject_undef64_exception(regs, hsr.len);
+        do_trap_smc(regs, hsr);
         break;
     case HSR_EC_SYSREG:
         GUEST_BUG_ON(psr_mode_is_32bit(regs->cpsr));
-- 
2.8.1


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