[xen staging] x86/shadow: Don't leave trace record field uninitialized

[patchbot@xxxxxxx]

commit 6a17e1199332c24b41bacccdc91dbeaf22653588
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed May 22 12:17:30 2024 +0200
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Jun 24 16:22:59 2024 +0100

    x86/shadow: Don't leave trace record field uninitialized
    
    The emulation_count field is set only conditionally right now. Convert
    all field setting to an initializer, thus guaranteeing that field to be
    set to 0 (default initialized) when GUEST_PAGING_LEVELS != 3.
    
    Rework trace_shadow_emulate() to be consistent with the other trace helpers.
    
    Coverity-ID: 1598430
    Fixes: 9a86ac1aa3d2 ("xentrace 5/7: Additional tracing for the shadow code")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
    Release-acked-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/x86/mm/shadow/multi.c | 29 ++++++++++++++---------------
 1 file changed, 14 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index a1caae9127..8e0046ae69 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -2064,30 +2064,29 @@ static void cf_check trace_emulate_write_val(
 #endif
 }
 
-static inline void trace_shadow_emulate(guest_l1e_t gl1e, unsigned long va)
+static inline void sh_trace_emulate(guest_l1e_t gl1e, unsigned long va)
 {
     if ( tb_init_done )
     {
         struct __packed {
-            /* for PAE, guest_l1e may be 64 while guest_va may be 32;
-               so put it first for alignment sake. */
+            /*
+             * For GUEST_PAGING_LEVELS=3 (PAE paging), guest_l1e is 64 while
+             * guest_va is 32.  Put it first to avoid padding.
+             */
             guest_l1e_t gl1e, write_val;
             guest_va_t va;
             uint32_t flags:29, emulation_count:3;
-        } d;
-        u32 event;
-
-        event = TRC_SHADOW_EMULATE | ((GUEST_PAGING_LEVELS-2)<<8);
-
-        d.gl1e = gl1e;
-        d.write_val.l1 = this_cpu(trace_emulate_write_val);
-        d.va = va;
+        } d = {
+            .gl1e            = gl1e,
+            .write_val.l1    = this_cpu(trace_emulate_write_val),
+            .va              = va,
 #if GUEST_PAGING_LEVELS == 3
-        d.emulation_count = this_cpu(trace_extra_emulation_count);
+            .emulation_count = this_cpu(trace_extra_emulation_count),
 #endif
-        d.flags = this_cpu(trace_shadow_path_flags);
+            .flags           = this_cpu(trace_shadow_path_flags),
+        };
 
-        trace(event, sizeof(d), &d);
+        sh_trace(TRC_SHADOW_EMULATE, sizeof(d), &d);
     }
 }
 #endif /* CONFIG_HVM */
@@ -2816,7 +2815,7 @@ static int cf_check sh_page_fault(
     }
 #endif /* PAE guest */
 
-    trace_shadow_emulate(gw.l1e, va);
+    sh_trace_emulate(gw.l1e, va);
  emulate_done:
     SHADOW_PRINTK("emulated\n");
     return EXCRET_fault_fixed;
--
generated by git-patchbot for /home/xen/git/xen.git#staging