migration/postcopy: Drop all atomic ops in blocktime feature

Now with the mutex protection it's not needed anymore.

Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250613141217.474825-4-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c
index 32fa06dabd54900ade9643b803a12c3cab51f4b5..81925532deecfd1dc631f510b900e64ee67907e6 100644 (file)
--- a/migration/postcopy-ram.c
+++ b/migration/postcopy-ram.c
@@ -849,12 +849,12 @@ void mark_postcopy_blocktime_begin(uintptr_t addr, uint32_t ptid,
 
     low_time_offset = get_low_time_offset(dc);
     if (dc->vcpu_addr[cpu] == 0) {
-        qatomic_inc(&dc->smp_cpus_down);
+        dc->smp_cpus_down++;
     }
 
-    qatomic_xchg(&dc->last_begin, low_time_offset);
-    qatomic_xchg(&dc->page_fault_vcpu_time[cpu], low_time_offset);
-    qatomic_xchg(&dc->vcpu_addr[cpu], addr);
+    dc->last_begin = low_time_offset;
+    dc->page_fault_vcpu_time[cpu] = low_time_offset;
+    dc->vcpu_addr[cpu] = addr;
 
     /*
      * The caller should only inject a blocktime entry when the page is
@@ -915,29 +915,26 @@ static void mark_postcopy_blocktime_end(uintptr_t addr)
     for (i = 0; i < smp_cpus; i++) {
         uint32_t vcpu_blocktime = 0;
 
-        read_vcpu_time = qatomic_fetch_add(&dc->page_fault_vcpu_time[i], 0);
-        if (qatomic_fetch_add(&dc->vcpu_addr[i], 0) != addr ||
-            read_vcpu_time == 0) {
+        read_vcpu_time = dc->page_fault_vcpu_time[i];
+        if (dc->vcpu_addr[i] != addr || read_vcpu_time == 0) {
             continue;
         }
-        qatomic_xchg(&dc->vcpu_addr[i], 0);
+        dc->vcpu_addr[i] = 0;
         vcpu_blocktime = low_time_offset - read_vcpu_time;
         affected_cpu += 1;
         /* we need to know is that mark_postcopy_end was due to
          * faulted page, another possible case it's prefetched
          * page and in that case we shouldn't be here */
-        if (!vcpu_total_blocktime &&
-            qatomic_fetch_add(&dc->smp_cpus_down, 0) == smp_cpus) {
+        if (!vcpu_total_blocktime && dc->smp_cpus_down == smp_cpus) {
             vcpu_total_blocktime = true;
         }
         /* continue cycle, due to one page could affect several vCPUs */
         dc->vcpu_blocktime[i] += vcpu_blocktime;
     }
 
-    qatomic_sub(&dc->smp_cpus_down, affected_cpu);
+    dc->smp_cpus_down -= affected_cpu;
     if (vcpu_total_blocktime) {
-        dc->total_blocktime += low_time_offset - qatomic_fetch_add(
-                &dc->last_begin, 0);
+        dc->total_blocktime += low_time_offset - dc->last_begin;
     }
     trace_mark_postcopy_blocktime_end(addr, dc, dc->total_blocktime,
                                       affected_cpu);