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[PATCH v4 4/8] hpet: move out main counter read into a separate block

Igor Mammedov posted 8 patches 2 months, 2 weeks 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>, 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>, Eduardo Habkost <eduardo@habkost.net>, Marcel Apfelbaum <marcel.apfelbaum@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>
[PATCH v4 4/8] hpet: move out main counter read into a separate block
Posted by Igor Mammedov 2 months, 2 weeks ago 
Follow up patche will switch main counter read to
lock-less mode. As preparation for that move relevant
branch into a separate top level block to make followup
patch cleaner/simplier by reducing contextual noise
when lock-less read is introduced.

no functional changes.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
v3:
  * drop 'addr <= 0xff' as addr == HPET_COUNTER is sufficient
     Peter Xu <peterx@redhat.com>
---
 hw/timer/hpet.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/hw/timer/hpet.c b/hw/timer/hpet.c
index ab5aa59ae4..c776afc0f2 100644
--- a/hw/timer/hpet.c
+++ b/hw/timer/hpet.c
@@ -431,6 +431,16 @@ static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
     addr &= ~4;
 
     QEMU_LOCK_GUARD(&s->lock);
+    if (addr == HPET_COUNTER) {
+        if (hpet_enabled(s)) {
+            cur_tick = hpet_get_ticks(s);
+        } else {
+            cur_tick = s->hpet_counter;
+        }
+        trace_hpet_ram_read_reading_counter(addr & 4, cur_tick);
+        return cur_tick >> shift;
+    }
+
     /*address range of all global regs*/
     if (addr <= 0xff) {
         switch (addr) {
@@ -438,14 +448,6 @@ static uint64_t hpet_ram_read(void *opaque, hwaddr addr,
             return s->capability >> shift;
         case HPET_CFG:
             return s->config >> shift;
-        case HPET_COUNTER:
-            if (hpet_enabled(s)) {
-                cur_tick = hpet_get_ticks(s);
-            } else {
-                cur_tick = s->hpet_counter;
-            }
-            trace_hpet_ram_read_reading_counter(addr & 4, cur_tick);
-            return cur_tick >> shift;
         case HPET_STATUS:
             return s->isr >> shift;
         default:
-- 
2.47.1
Re: [PATCH v4 4/8] hpet: move out main counter read into a separate block
Posted by Zhao Liu 2 months ago 
On Thu, Aug 14, 2025 at 06:05:56PM +0200, Igor Mammedov wrote:
> Date: Thu, 14 Aug 2025 18:05:56 +0200
> From: Igor Mammedov <imammedo@redhat.com>
> Subject: [PATCH v4 4/8] hpet: move out main counter read into a separate
>  block
> 
> Follow up patche will switch main counter read to
> lock-less mode. As preparation for that move relevant
> branch into a separate top level block to make followup
> patch cleaner/simplier by reducing contextual noise
> when lock-less read is introduced.
> 
> no functional changes.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> ---
> v3:
>   * drop 'addr <= 0xff' as addr == HPET_COUNTER is sufficient
>      Peter Xu <peterx@redhat.com>
> ---
>  hw/timer/hpet.c | 18 ++++++++++--------
>  1 file changed, 10 insertions(+), 8 deletions(-)

Reviewed-by: Zhao Liu <zhao1.liu@intel.com>

Patchew 2.1-devel-b67e4c2

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