[PATCH v3 17/22] x86/entry: Rework the comment about SYSCALL and DF

[Andrew Cooper <andrew.cooper3@citrix.com>]

It's soon going to be needed in a second location.

Right now it's misleading saying that nothing else would be cleared.  It's
missing the more important point that SYSCALLs are treated like all other
interrupts and exceptions, and undergo normal flags handling there.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
CC: Jan Beulich <JBeulich@suse.com>
CC: Roger Pau Monné <roger.pau@citrix.com>

v2:
 * New
---
 xen/arch/x86/x86_64/entry.S | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 01b431793b7b..ca446c6ff0ce 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -39,10 +39,9 @@ FUNC_LOCAL(switch_to_kernel)
         leal  (,%rcx,TBF_INTERRUPT),%ecx
 
         /*
-         * The PV ABI hardcodes the (guest-inaccessible and virtual)
-         * SYSCALL_MASK MSR such that DF (and nothing else) would be cleared.
-         * Note that the equivalent of IF (VGCF_syscall_disables_events) is
-         * dealt with separately above.
+         * The PV ABI, given no virtual SYSCALL_MASK, hardcodes that DF is
+         * cleared.  Other flags are handled in the same way as interrupts and
+         * exceptions in create_bounce_frame().
          */
         mov   $~X86_EFLAGS_DF, %esi
 
-- 
2.39.5