[xen staging] x86/monitor: allow fast-singlestepping without enabling singlestep monitor

[patchbot@xxxxxxx]

commit 410ef3343924b5a3928bbe8e392491992b322cf0
Author:     Petr Beneš <w1benny@xxxxxxxxx>
AuthorDate: Sun Apr 14 18:21:14 2024 +0000
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Apr 23 22:49:01 2024 +0100

    x86/monitor: allow fast-singlestepping without enabling singlestep monitor
    
    Reorder the condition checks within the HVM_MONITOR_SINGLESTEP_BREAKPOINT
    case to enable fast singlestepping independently of the singlestep monitor
    being enabled. Previously, fast singlestepping required the singlestep
    monitor to be explicitly enabled through xc_monitor_singlestep, even though
    it operates entirely within Xen and does not generate external events.
    
    Signed-off-by: Petr Beneš <w1benny@xxxxxxxxx>
    Acked-by: Tamas K Lengyel <tamas@xxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/monitor.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/monitor.c b/xen/arch/x86/hvm/monitor.c
index 4f500beaf5..2a8ff07ec9 100644
--- a/xen/arch/x86/hvm/monitor.c
+++ b/xen/arch/x86/hvm/monitor.c
@@ -178,8 +178,6 @@ int hvm_monitor_debug(unsigned long rip, enum 
hvm_monitor_debug_type type,
         break;
 
     case HVM_MONITOR_SINGLESTEP_BREAKPOINT:
-        if ( !ad->monitor.singlestep_enabled )
-            return 0;
         if ( curr->arch.hvm.fast_single_step.enabled )
         {
             p2m_altp2m_check(curr, curr->arch.hvm.fast_single_step.p2midx);
@@ -188,6 +186,8 @@ int hvm_monitor_debug(unsigned long rip, enum 
hvm_monitor_debug_type type,
             curr->arch.hvm.fast_single_step.p2midx = 0;
             return 0;
         }
+        if ( !ad->monitor.singlestep_enabled )
+            return 0;
         req.reason = VM_EVENT_REASON_SINGLESTEP;
         req.u.singlestep.gfn = gfn_of_rip(rip);
         sync = true;
--
generated by git-patchbot for /home/xen/git/xen.git#staging