[xen staging] x86/hvm: Use for_each_set_bit() in hvm_emulate_writeback()

[patchbot@xxxxxxx]

commit e7e0d485e993e97b1c816adcfc610e7c7258ce96
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Tue Jun 11 20:03:32 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Mar 17 16:08:34 2025 +0000

    x86/hvm: Use for_each_set_bit() in hvm_emulate_writeback()
    
    ... which is more consise than the opencoded form, and more efficient when
    compiled.
    
    Furthermore, now that find_{first,next}_bit() are no longer in use, the
    seg_reg_{accessed,dirty} fields aren't forced to be unsigned long, although
    they do need to remain unsigned int because of __set_bit() elsewhere.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/emulate.c             | 15 ++++-----------
 xen/arch/x86/include/asm/hvm/emulate.h |  4 ++--
 2 files changed, 6 insertions(+), 13 deletions(-)

diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 1db14642b3..dbf6b5543a 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -3022,18 +3022,11 @@ void hvm_emulate_init_per_insn(
 void hvm_emulate_writeback(
     struct hvm_emulate_ctxt *hvmemul_ctxt)
 {
-    enum x86_segment seg;
-
-    seg = find_first_bit(&hvmemul_ctxt->seg_reg_dirty,
-                         ARRAY_SIZE(hvmemul_ctxt->seg_reg));
+    struct vcpu *curr = current;
+    unsigned int dirty = hvmemul_ctxt->seg_reg_dirty;
 
-    while ( seg < ARRAY_SIZE(hvmemul_ctxt->seg_reg) )
-    {
-        hvm_set_segment_register(current, seg, &hvmemul_ctxt->seg_reg[seg]);
-        seg = find_next_bit(&hvmemul_ctxt->seg_reg_dirty,
-                            ARRAY_SIZE(hvmemul_ctxt->seg_reg),
-                            seg+1);
-    }
+    for_each_set_bit ( seg, dirty )
+        hvm_set_segment_register(curr, seg, &hvmemul_ctxt->seg_reg[seg]);
 }
 
 /*
diff --git a/xen/arch/x86/include/asm/hvm/emulate.h 
b/xen/arch/x86/include/asm/hvm/emulate.h
index d61eacfaa7..c7a2d2a5be 100644
--- a/xen/arch/x86/include/asm/hvm/emulate.h
+++ b/xen/arch/x86/include/asm/hvm/emulate.h
@@ -37,8 +37,8 @@ struct hvm_emulate_ctxt {
     unsigned int insn_buf_bytes;
 
     struct segment_register seg_reg[10];
-    unsigned long seg_reg_accessed;
-    unsigned long seg_reg_dirty;
+    unsigned int seg_reg_accessed;
+    unsigned int seg_reg_dirty;
 
     /*
      * MFNs behind temporary mappings in the write callback.  The length is
--
generated by git-patchbot for /home/xen/git/xen.git#staging