No bits, other than arithmetic ones and the resume flag (which will most
likely change from 1 to 0), can be changed by the instructions we permit.
Extend the check to cover other flags.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
v2:
* Extend to all unexpected bits.
---
xen/arch/x86/traps.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 4f29c3a..ea0ce52 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -3012,9 +3012,11 @@ static int emulate_privileged_op(struct cpu_user_regs
*regs)
/*
* Un-mirror virtualized state from EFLAGS.
- * Nothing we allow to be emulated can change TF, IF, or IOPL.
+ * Nothing we allow to be emulated can change anything other than the
+ * arithmetic bits, and the resume flag.
*/
- ASSERT(!((regs->_eflags ^ eflags) & (X86_EFLAGS_IF | X86_EFLAGS_IOPL)));
+ ASSERT(!((regs->_eflags ^ eflags) &
+ ~(X86_EFLAGS_RF | X86_EFLAGS_ARITH_MASK)));
regs->_eflags |= X86_EFLAGS_IF;
regs->_eflags &= ~X86_EFLAGS_IOPL;
--
2.1.4
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