[xen master] xen/bitops: Convert 'hweight(x) > 1' to new multiple_bits_set()

[patchbot@xxxxxxx]

commit d35fb45d3c7b6d80f290ea6feea978d6ac6cca89
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Thu Aug 22 17:01:53 2024 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Sep 3 20:22:18 2024 +0100

    xen/bitops: Convert 'hweight(x) > 1' to new multiple_bits_set()
    
    Using hweight() is an especially expensive way of determining simply if
    multiple bits are set in a value.  Worse, 4 of the 10 hweight() calls in Xen
    are of this form.
    
    Switch to the new multiple_bits_set() helper.  This is far more efficient 
than
    the longhand hweight() algorithm and, owing to its simplicity, likely more
    efficient than even a dedicated instruction on a superscalar processor.
    
    No functional change.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/cpu/vpmu.c   |  2 +-
 xen/arch/x86/hvm/vlapic.c | 10 ++++++----
 xen/common/numa.c         |  2 +-
 3 files changed, 8 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/cpu/vpmu.c b/xen/arch/x86/cpu/vpmu.c
index b2ba999412..a5bb1689c7 100644
--- a/xen/arch/x86/cpu/vpmu.c
+++ b/xen/arch/x86/cpu/vpmu.c
@@ -673,7 +673,7 @@ long do_xenpmu_op(
     {
         if ( (pmu_params.val &
               ~(XENPMU_MODE_SELF | XENPMU_MODE_HV | XENPMU_MODE_ALL)) ||
-             (hweight64(pmu_params.val) > 1) )
+             multiple_bits_set(pmu_params.val) )
             return -EINVAL;
 
         /* 32-bit dom0 can only sample itself. */
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 2ec9594271..4a3e21a65f 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -467,12 +467,14 @@ static bool is_multicast_dest(struct vlapic *vlapic, 
unsigned int short_hand,
         return short_hand != APIC_DEST_SELF;
 
     if ( vlapic_x2apic_mode(vlapic) )
-        return dest_mode ? hweight16(dest) > 1 : dest == 0xffffffffU;
+        return dest_mode ? multiple_bits_set((uint16_t)dest)
+                         : dest == 0xffffffffU;
 
     if ( dest_mode )
-        return hweight8(dest &
-                        GET_xAPIC_DEST_FIELD(vlapic_get_reg(vlapic,
-                                                            APIC_DFR))) > 1;
+    {
+        dest &= GET_xAPIC_DEST_FIELD(vlapic_get_reg(vlapic, APIC_DFR));
+        return multiple_bits_set((uint8_t)dest);
+    }
 
     return dest == 0xff;
 }
diff --git a/xen/common/numa.c b/xen/common/numa.c
index 28a09766fa..ce3991929c 100644
--- a/xen/common/numa.c
+++ b/xen/common/numa.c
@@ -546,7 +546,7 @@ static int __init numa_emulation(unsigned long start_pfn,
     uint64_t sz = pfn_to_paddr(end_pfn - start_pfn) / numa_fake;
 
     /* Kludge needed for the hash function */
-    if ( hweight64(sz) > 1 )
+    if ( multiple_bits_set(sz) )
     {
         uint64_t x = 1;
 
--
generated by git-patchbot for /home/xen/git/xen.git#master