[PULL 28/28] tcg: move interrupt caching and single step masking closer to user

Paolo Bonzini posted 28 patches 1 month ago
Maintainers: Richard Henderson <richard.henderson@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Riku Voipio <riku.voipio@iki.fi>, "Michael S. Tsirkin" <mst@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Ani Sinha <anisinha@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Eduardo Habkost <eduardo@habkost.net>, Thomas Huth <thuth@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@linux.ibm.com>, David Hildenbrand <david@redhat.com>, Jason Herne <jjherne@linux.ibm.com>, Stafford Horne <shorne@gmail.com>, "Philippe Mathieu-Daudé" <philmd@linaro.org>, Yanan Wang <wangyanan55@huawei.com>, Zhao Liu <zhao1.liu@intel.com>, Peter Xu <peterx@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Alexander Graf <agraf@csgraf.de>, Mads Ynddal <mads@ynddal.dk>, Michael Rolnik <mrolnik@gmail.com>, Helge Deller <deller@gmx.de>, Cameron Esfahani <dirty@apple.com>, Roman Bolshakov <rbolshakov@ddn.com>, Phil Dennis-Jordan <phil@philjordan.eu>, Marcelo Tosatti <mtosatti@redhat.com>, Reinoud Zandijk <reinoud@netbsd.org>, Sunil Muthuswamy <sunilmut@microsoft.com>, Song Gao <gaosong@loongson.cn>, Laurent Vivier <laurent@vivier.eu>, "Edgar E. Iglesias" <edgar.iglesias@gmail.com>, Aurelien Jarno <aurelien@aurel32.net>, Jiaxun Yang <jiaxun.yang@flygoat.com>, Aleksandar Rikalo <arikalo@gmail.com>, Huacai Chen <chenhuacai@kernel.org>, Nicholas Piggin <npiggin@gmail.com>, Chinmay Rath <rathc@linux.ibm.com>, Harsh Prateek Bora <harshpb@linux.ibm.com>, Yoshinori Sato <yoshinori.sato@nifty.com>, Ilya Leoshkevich <iii@linux.ibm.com>, Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>, Artyom Tarasenko <atar4qemu@gmail.com>
[PULL 28/28] tcg: move interrupt caching and single step masking closer to user
Posted by Paolo Bonzini 1 month ago
From: Igor Mammedov <imammedo@redhat.com>

in cpu_handle_interrupt() the only place where cached interrupt_request
might have effect is when CPU_INTERRUPT_SSTEP_MASK applied and
cached interrupt_request handed over to cpu_exec_interrupt() and
need_replay_interrupt().

Simplify code by moving interrupt_request caching and CPU_INTERRUPT_SSTEP_MASK
masking into the block where it actually matters and drop reloading cached value
from CPUState:interrupt_request as the rest of the code directly uses
CPUState:interrupt_request.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Link: https://lore.kernel.org/r/20250814160600.2327672-9-imammedo@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 accel/tcg/cpu-exec.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/accel/tcg/cpu-exec.c b/accel/tcg/cpu-exec.c
index 96c124aa720..8491e5badd1 100644
--- a/accel/tcg/cpu-exec.c
+++ b/accel/tcg/cpu-exec.c
@@ -782,13 +782,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
     assert(!cpu_test_interrupt(cpu, ~0));
 #else
     if (unlikely(cpu_test_interrupt(cpu, ~0))) {
-        int interrupt_request;
         bql_lock();
-        interrupt_request = cpu->interrupt_request;
-        if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
-            /* Mask out external interrupts for this step. */
-            interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
-        }
         if (cpu_test_interrupt(cpu, CPU_INTERRUPT_DEBUG)) {
             cpu->interrupt_request &= ~CPU_INTERRUPT_DEBUG;
             cpu->exception_index = EXCP_DEBUG;
@@ -806,6 +800,7 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
             return true;
         } else {
             const TCGCPUOps *tcg_ops = cpu->cc->tcg_ops;
+            int interrupt_request = cpu->interrupt_request;
 
             if (cpu_test_interrupt(cpu, CPU_INTERRUPT_RESET)) {
                 replay_interrupt();
@@ -814,6 +809,11 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
                 return true;
             }
 
+            if (unlikely(cpu->singlestep_enabled & SSTEP_NOIRQ)) {
+                /* Mask out external interrupts for this step. */
+                interrupt_request &= ~CPU_INTERRUPT_SSTEP_MASK;
+            }
+
             /*
              * The target hook has 3 exit conditions:
              * False when the interrupt isn't processed,
@@ -838,9 +838,6 @@ static inline bool cpu_handle_interrupt(CPUState *cpu,
                 cpu->exception_index = -1;
                 *last_tb = NULL;
             }
-            /* The target hook may have updated the 'cpu->interrupt_request';
-             * reload the 'interrupt_request' value */
-            interrupt_request = cpu->interrupt_request;
         }
         if (cpu_test_interrupt(cpu, CPU_INTERRUPT_EXITTB)) {
             cpu->interrupt_request &= ~CPU_INTERRUPT_EXITTB;
-- 
2.51.0