sh_trace_gfn_va() is very similar to sh_trace_gl1e_va(), and a rather shorter
name than trace_shadow_emulate_other().  Like sh_trace_gl1e_va(), there is no
need to pack the trace record.

No functional change.

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

v2:
 * New
---
 xen/arch/x86/mm/shadow/multi.c | 40 ++++++++++++++++------------------
 1 file changed, 19 insertions(+), 21 deletions(-)

diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c
index f0a9cc527c0b..d2fe4e148fe0 100644
--- a/xen/arch/x86/mm/shadow/multi.c
+++ b/xen/arch/x86/mm/shadow/multi.c
@@ -2010,29 +2010,30 @@ static void sh_trace_gl1e_va(uint32_t event, guest_l1e_t gl1e, guest_va_t va)
     }
 }
 
-static inline void trace_shadow_emulate_other(u32 event,
-                                                 guest_va_t va,
-                                                 gfn_t gfn)
+/* Shadow trace event with a gfn, linear address and flags. */
+static void sh_trace_gfn_va(uint32_t event, gfn_t gfn, guest_va_t 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. */
+        struct {
+            /*
+             * For GUEST_PAGING_LEVELS=3 (PAE paging), gfn is 64 while
+             * guest_va is 32.  Put it first to avoid padding.
+             */
 #if GUEST_PAGING_LEVELS == 2
-            u32 gfn;
+            uint32_t gfn;
 #else
-            u64 gfn;
+            uint64_t gfn;
 #endif
             guest_va_t va;
-        } d;
-
-        event |= ((GUEST_PAGING_LEVELS-2)<<8);
-
-        d.gfn=gfn_x(gfn);
-        d.va = va;
+            uint32_t flags;
+        } d = {
+            .gfn = gfn_x(gfn),
+            .va = va,
+            .flags = this_cpu(trace_shadow_path_flags),
+        };
 
-        trace(event, sizeof(d), &d);
+        sh_trace(event, sizeof(d), &d);
     }
 }
 
@@ -2603,8 +2604,7 @@ static int cf_check sh_page_fault(
                       mfn_x(gmfn));
         perfc_incr(shadow_fault_emulate_failed);
         shadow_remove_all_shadows(d, gmfn);
-        trace_shadow_emulate_other(TRC_SHADOW_EMULATE_UNSHADOW_USER,
-                                      va, gfn);
+        sh_trace_gfn_va(TRC_SHADOW_EMULATE_UNSHADOW_USER, gfn, va);
         goto done;
     }
 
@@ -2683,8 +2683,7 @@ static int cf_check sh_page_fault(
         }
 #endif
         shadow_remove_all_shadows(d, gmfn);
-        trace_shadow_emulate_other(TRC_SHADOW_EMULATE_UNSHADOW_EVTINJ,
-                                   va, gfn);
+        sh_trace_gfn_va(TRC_SHADOW_EMULATE_UNSHADOW_EVTINJ, gfn, va);
         return EXCRET_fault_fixed;
     }
 
@@ -2739,8 +2738,7 @@ static int cf_check sh_page_fault(
          * though, this is a hint that this page should not be shadowed. */
         shadow_remove_all_shadows(d, gmfn);
 
-        trace_shadow_emulate_other(TRC_SHADOW_EMULATE_UNSHADOW_UNHANDLED,
-                                   va, gfn);
+        sh_trace_gfn_va(TRC_SHADOW_EMULATE_UNSHADOW_UNHANDLED, gfn, va);
         goto emulate_done;
     }
 
-- 
2.30.2

On 22.05.2024 15:17, Andrew Cooper wrote:
> sh_trace_gfn_va() is very similar to sh_trace_gl1e_va(), and a rather shorter
> name than trace_shadow_emulate_other().  Like sh_trace_gl1e_va(), there is no
> need to pack the trace record.

Provided record size can freely change (here for the 3-level case) without
breaking consumers, i.e. similar to patch 2.

> --- a/xen/arch/x86/mm/shadow/multi.c
> +++ b/xen/arch/x86/mm/shadow/multi.c
> @@ -2010,29 +2010,30 @@ static void sh_trace_gl1e_va(uint32_t event, guest_l1e_t gl1e, guest_va_t va)
>      }
>  }
>  
> -static inline void trace_shadow_emulate_other(u32 event,
> -                                                 guest_va_t va,
> -                                                 gfn_t gfn)
> +/* Shadow trace event with a gfn, linear address and flags. */
> +static void sh_trace_gfn_va(uint32_t event, gfn_t gfn, guest_va_t 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. */
> +        struct {
> +            /*
> +             * For GUEST_PAGING_LEVELS=3 (PAE paging), gfn is 64 while
> +             * guest_va is 32.  Put it first to avoid padding.
> +             */
>  #if GUEST_PAGING_LEVELS == 2
> -            u32 gfn;
> +            uint32_t gfn;
>  #else
> -            u64 gfn;
> +            uint64_t gfn;
>  #endif
>              guest_va_t va;
> -        } d;
> -
> -        event |= ((GUEST_PAGING_LEVELS-2)<<8);
> -
> -        d.gfn=gfn_x(gfn);
> -        d.va = va;
> +            uint32_t flags;
> +        } d = {
> +            .gfn = gfn_x(gfn),
> +            .va = va,
> +            .flags = this_cpu(trace_shadow_path_flags),
> +        };

There's again no function call involved here, so having tb_init_done checked
only in (inlined) sh_trace() ought to again be enough?

Jan