[PATCH 07/19] cpu-common: use atomic access for interrupt_request

[Paolo Bonzini <pbonzini@redhat.com>]

Writes to interrupt_request used non-atomic accesses, but there are a
few cases where the access was not protected by the BQL.  Now that
there is a full set of helpers, it's easier to guarantee that
interrupt_request accesses are fully atomic, so just drop the
requirement instead of fixing them.

Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/hw/core/cpu.h |  1 -
 hw/core/cpu-common.c  | 12 +-----------
 system/cpus.c         |  3 +--
 3 files changed, 2 insertions(+), 14 deletions(-)

diff --git a/include/hw/core/cpu.h b/include/hw/core/cpu.h
index b01a0cffd64..23bd02277f4 100644
--- a/include/hw/core/cpu.h
+++ b/include/hw/core/cpu.h
@@ -495,7 +495,6 @@ struct CPUState {
     bool exit_request;
     int exclusive_context_count;
     uint32_t cflags_next_tb;
-    /* updates protected by BQL */
     uint32_t interrupt_request;
     int singlestep_enabled;
     int64_t icount_budget;
diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
index 259cf2a3c36..152abc9024b 100644
--- a/hw/core/cpu-common.c
+++ b/hw/core/cpu-common.c
@@ -67,19 +67,9 @@ CPUState *cpu_create(const char *typename)
     return cpu;
 }
 
-/* Resetting the IRQ comes from across the code base so we take the
- * BQL here if we need to.  cpu_interrupt assumes it is held.*/
 void cpu_reset_interrupt(CPUState *cpu, int mask)
 {
-    bool need_lock = !bql_locked();
-
-    if (need_lock) {
-        bql_lock();
-    }
-    cpu->interrupt_request &= ~mask;
-    if (need_lock) {
-        bql_unlock();
-    }
+    qatomic_and(&cpu->interrupt_request, ~mask);
 }
 
 void cpu_exit(CPUState *cpu)
diff --git a/system/cpus.c b/system/cpus.c
index 437848b5eb4..9bfbe2b0607 100644
--- a/system/cpus.c
+++ b/system/cpus.c
@@ -257,8 +257,7 @@ int64_t cpus_get_elapsed_ticks(void)
 void cpu_set_interrupt(CPUState *cpu, int mask)
 {
     /* Pairs with cpu_test_interrupt(). */
-    qatomic_store_release(&cpu->interrupt_request,
-        cpu->interrupt_request | mask);
+    qatomic_or(&cpu->interrupt_request, mask);
 }
 
 void generic_handle_interrupt(CPUState *cpu, int mask)
-- 
2.51.0