Re: [PATCH v4] hw/rtc/mc146818rtc: Make this rtc device target independent

[Bernhard Beschow]

Am 29. Dezember 2022 10:58:48 UTC schrieb Thomas Huth <thuth@redhat.com>:
>The only reason for this code being target dependent is the apic-related
>code in rtc_policy_slew_deliver_irq(). Since these apic functions are rather
>simple, we can easily move them into a new, separate file (apic_irqcount.c)
>which will always be compiled and linked if either APIC or the mc146818 device
>are required. This way we can get rid of the #ifdef TARGET_I386 switches in
>mc146818rtc.c and declare it in the softmmu_ss instead of specific_ss, so
>that the code only gets compiled once for all targets.
>
>Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>Reviewed-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
>Signed-off-by: Thomas Huth <thuth@redhat.com>
>---
> v4: Check for QEMU_ARCH_I386 instead of looking for an APIC

Can we find a more appropriate name for the helpers than "apic" then? If the 
slew tick policy is a workaround for (x86-) KVM I propose to do s/apic/kvm/ 
while still compiling for every target.

>
> include/hw/i386/apic.h          |  1 +
> include/hw/i386/apic_internal.h |  1 -
> include/hw/rtc/mc146818rtc.h    |  1 +
> hw/intc/apic_common.c           | 27 -----------------
> hw/intc/apic_irqcount.c         | 53 +++++++++++++++++++++++++++++++++
> hw/rtc/mc146818rtc.c            | 26 +++++-----------
> hw/intc/meson.build             |  6 +++-
> hw/rtc/meson.build              |  3 +-
> 8 files changed, 69 insertions(+), 49 deletions(-)
> create mode 100644 hw/intc/apic_irqcount.c
>
>diff --git a/include/hw/i386/apic.h b/include/hw/i386/apic.h
>index da1d2fe155..96b9939425 100644
>--- a/include/hw/i386/apic.h
>+++ b/include/hw/i386/apic.h
>@@ -9,6 +9,7 @@ int apic_accept_pic_intr(DeviceState *s);
> void apic_deliver_pic_intr(DeviceState *s, int level);
> void apic_deliver_nmi(DeviceState *d);
> int apic_get_interrupt(DeviceState *s);
>+void apic_report_irq_delivered(int delivered);
> void apic_reset_irq_delivered(void);
> int apic_get_irq_delivered(void);
> void cpu_set_apic_base(DeviceState *s, uint64_t val);
>diff --git a/include/hw/i386/apic_internal.h b/include/hw/i386/apic_internal.h
>index c175e7e718..e61ad04769 100644
>--- a/include/hw/i386/apic_internal.h
>+++ b/include/hw/i386/apic_internal.h
>@@ -199,7 +199,6 @@ typedef struct VAPICState {
> 
> extern bool apic_report_tpr_access;
> 
>-void apic_report_irq_delivered(int delivered);
> bool apic_next_timer(APICCommonState *s, int64_t current_time);
> void apic_enable_tpr_access_reporting(DeviceState *d, bool enable);
> void apic_enable_vapic(DeviceState *d, hwaddr paddr);
>diff --git a/include/hw/rtc/mc146818rtc.h b/include/hw/rtc/mc146818rtc.h
>index 1db0fcee92..45bcd6f040 100644
>--- a/include/hw/rtc/mc146818rtc.h
>+++ b/include/hw/rtc/mc146818rtc.h
>@@ -55,5 +55,6 @@ ISADevice *mc146818_rtc_init(ISABus *bus, int base_year,
>                              qemu_irq intercept_irq);
> void rtc_set_memory(ISADevice *dev, int addr, int val);
> int rtc_get_memory(ISADevice *dev, int addr);
>+void qmp_rtc_reset_reinjection(Error **errp);
> 
> #endif /* HW_RTC_MC146818RTC_H */
>diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c
>index 2a20982066..b0f85f9384 100644
>--- a/hw/intc/apic_common.c
>+++ b/hw/intc/apic_common.c
>@@ -33,7 +33,6 @@
> #include "hw/sysbus.h"
> #include "migration/vmstate.h"
> 
>-static int apic_irq_delivered;
> bool apic_report_tpr_access;
> 
> void cpu_set_apic_base(DeviceState *dev, uint64_t val)
>@@ -122,32 +121,6 @@ void apic_handle_tpr_access_report(DeviceState *dev, 
>target_ulong ip,
>     vapic_report_tpr_access(s->vapic, CPU(s->cpu), ip, access);
> }
> 
>-void apic_report_irq_delivered(int delivered)
>-{
>-    apic_irq_delivered += delivered;
>-
>-    trace_apic_report_irq_delivered(apic_irq_delivered);
>-}
>-
>-void apic_reset_irq_delivered(void)
>-{
>-    /* Copy this into a local variable to encourage gcc to emit a plain
>-     * register for a sys/sdt.h marker.  For details on this workaround, see:
>-     * https://sourceware.org/bugzilla/show_bug.cgi?id=13296
>-     */
>-    volatile int a_i_d = apic_irq_delivered;
>-    trace_apic_reset_irq_delivered(a_i_d);
>-
>-    apic_irq_delivered = 0;
>-}
>-
>-int apic_get_irq_delivered(void)
>-{
>-    trace_apic_get_irq_delivered(apic_irq_delivered);
>-
>-    return apic_irq_delivered;
>-}
>-
> void apic_deliver_nmi(DeviceState *dev)
> {
>     APICCommonState *s = APIC_COMMON(dev);
>diff --git a/hw/intc/apic_irqcount.c b/hw/intc/apic_irqcount.c
>new file mode 100644
>index 0000000000..0aadef1cb5
>--- /dev/null
>+++ b/hw/intc/apic_irqcount.c
>@@ -0,0 +1,53 @@
>+/*
>+ * APIC support - functions for counting the delivered IRQs.
>+ * (this code is in a separate file since it is used from the
>+ * mc146818rtc code on targets without APIC, too)
>+ *
>+ *  Copyright (c) 2011      Jan Kiszka, Siemens AG
>+ *
>+ * This library is free software; you can redistribute it and/or
>+ * modify it under the terms of the GNU Lesser General Public
>+ * License as published by the Free Software Foundation; either
>+ * version 2.1 of the License, or (at your option) any later version.
>+ *
>+ * This library is distributed in the hope that it will be useful,
>+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
>+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>+ * Lesser General Public License for more details.
>+ *
>+ * You should have received a copy of the GNU Lesser General Public
>+ * License along with this library; if not, see <http://www.gnu.org/licenses/>
>+ */
>+
>+#include "qemu/osdep.h"
>+#include "hw/i386/apic.h"
>+#include "trace.h"
>+
>+static int apic_irq_delivered;
>+
>+void apic_report_irq_delivered(int delivered)
>+{
>+    apic_irq_delivered += delivered;
>+
>+    trace_apic_report_irq_delivered(apic_irq_delivered);
>+}
>+
>+void apic_reset_irq_delivered(void)
>+{
>+    /*
>+     * Copy this into a local variable to encourage gcc to emit a plain
>+     * register for a sys/sdt.h marker.  For details on this workaround, see:
>+     * https://sourceware.org/bugzilla/show_bug.cgi?id=13296
>+     */
>+    volatile int a_i_d = apic_irq_delivered;
>+    trace_apic_reset_irq_delivered(a_i_d);
>+
>+    apic_irq_delivered = 0;
>+}
>+
>+int apic_get_irq_delivered(void)
>+{
>+    trace_apic_get_irq_delivered(apic_irq_delivered);
>+
>+    return apic_irq_delivered;
>+}
>diff --git a/hw/rtc/mc146818rtc.c b/hw/rtc/mc146818rtc.c
>index 1ebb412479..5477ff6dbb 100644
>--- a/hw/rtc/mc146818rtc.c
>+++ b/hw/rtc/mc146818rtc.c
>@@ -31,6 +31,7 @@
> #include "hw/qdev-properties.h"
> #include "hw/qdev-properties-system.h"
> #include "qemu/timer.h"
>+#include "sysemu/arch_init.h"
> #include "sysemu/sysemu.h"
> #include "sysemu/replay.h"
> #include "sysemu/reset.h"
>@@ -43,11 +44,7 @@
> #include "qapi/qapi-events-misc.h"
> #include "qapi/visitor.h"
> #include "hw/rtc/mc146818rtc_regs.h"
>-
>-#ifdef TARGET_I386
>-#include "qapi/qapi-commands-misc-target.h"
> #include "hw/i386/apic.h"
>-#endif
> 
> //#define DEBUG_CMOS
> //#define DEBUG_COALESCED
>@@ -112,7 +109,6 @@ static void rtc_coalesced_timer_update(RTCState *s)
> static QLIST_HEAD(, RTCState) rtc_devices =
>     QLIST_HEAD_INITIALIZER(rtc_devices);
> 
>-#ifdef TARGET_I386
> void qmp_rtc_reset_reinjection(Error **errp)
> {
>     RTCState *s;
>@@ -145,13 +141,6 @@ static void rtc_coalesced_timer(void *opaque)
> 
>     rtc_coalesced_timer_update(s);
> }
>-#else
>-static bool rtc_policy_slew_deliver_irq(RTCState *s)
>-{
>-    assert(0);
>-    return false;
>-}
>-#endif
> 
> static uint32_t rtc_periodic_clock_ticks(RTCState *s)
> {
>@@ -922,14 +911,15 @@ static void rtc_realizefn(DeviceState *dev, Error **errp)
>     rtc_set_date_from_host(isadev);
> 
>     switch (s->lost_tick_policy) {
>-#ifdef TARGET_I386
>-    case LOST_TICK_POLICY_SLEW:
>-        s->coalesced_timer =
>-            timer_new_ns(rtc_clock, rtc_coalesced_timer, s);
>-        break;
>-#endif
>     case LOST_TICK_POLICY_DISCARD:
>         break;
>+    case LOST_TICK_POLICY_SLEW:
>+        /* Slew tick policy is only available on x86 */
>+        if (arch_type == QEMU_ARCH_I386) {

This reflects the intention much better than before, which is nice.

How does `arch_type` play together with qemu-system-all? IIUC it should be 
possible to load all arch backends simultaneously while `arch_type` is an 
external symbol defined by each arch backend differently. So this seems to 
conflict.

Can we just add a property such as "slew-tick-policy-available" instead? It 
should default to false and all x86 machines would need to opt in explicitly. 
We could even error out in rtc_realize() if an attempt is made to enable the 
workaround although not available.

I still wonder if the slew tick policy is a workaround specific for x86-KVM. If 
so, we might only set the property to true if KVM is enabled.

Best regards,
Bernhard

>+            s->coalesced_timer = timer_new_ns(rtc_clock, rtc_coalesced_timer, 
>s);
>+            break;
>+        }
>+        /* fallthrough */
>     default:
>         error_setg(errp, "Invalid lost tick policy.");
>         return;
>diff --git a/hw/intc/meson.build b/hw/intc/meson.build
>index bcbf22ff51..036ad1936b 100644
>--- a/hw/intc/meson.build
>+++ b/hw/intc/meson.build
>@@ -25,8 +25,12 @@ softmmu_ss.add(when: 'CONFIG_XILINX', if_true: 
>files('xilinx_intc.c'))
> softmmu_ss.add(when: 'CONFIG_XLNX_ZYNQMP', if_true: 
> files('xlnx-zynqmp-ipi.c'))
> softmmu_ss.add(when: 'CONFIG_XLNX_ZYNQMP_PMU', if_true: 
> files('xlnx-pmu-iomod-intc.c'))
> 
>-specific_ss.add(when: 'CONFIG_ALLWINNER_A10_PIC', if_true: 
>files('allwinner-a10-pic.c'))
>+if config_all_devices.has_key('CONFIG_APIC') or 
>config_all_devices.has_key('CONFIG_MC146818RTC')
>+    softmmu_ss.add(files('apic_irqcount.c'))
>+endif
> specific_ss.add(when: 'CONFIG_APIC', if_true: files('apic.c', 
> 'apic_common.c'))
>+
>+specific_ss.add(when: 'CONFIG_ALLWINNER_A10_PIC', if_true: 
>files('allwinner-a10-pic.c'))
> specific_ss.add(when: 'CONFIG_ARM_GIC', if_true: 
> files('arm_gicv3_cpuif_common.c'))
> specific_ss.add(when: 'CONFIG_ARM_GICV3_TCG', if_true: 
> files('arm_gicv3_cpuif.c'))
> specific_ss.add(when: 'CONFIG_ARM_GIC_KVM', if_true: files('arm_gic_kvm.c'))
>diff --git a/hw/rtc/meson.build b/hw/rtc/meson.build
>index dc33973384..34a4d316fa 100644
>--- a/hw/rtc/meson.build
>+++ b/hw/rtc/meson.build
>@@ -13,5 +13,4 @@ softmmu_ss.add(when: 'CONFIG_ASPEED_SOC', if_true: 
>files('aspeed_rtc.c'))
> softmmu_ss.add(when: 'CONFIG_GOLDFISH_RTC', if_true: files('goldfish_rtc.c'))
> softmmu_ss.add(when: 'CONFIG_LS7A_RTC', if_true: files('ls7a_rtc.c'))
> softmmu_ss.add(when: 'CONFIG_ALLWINNER_H3', if_true: files('allwinner-rtc.c'))
>-
>-specific_ss.add(when: 'CONFIG_MC146818RTC', if_true: files('mc146818rtc.c'))
>+softmmu_ss.add(when: 'CONFIG_MC146818RTC', if_true: files('mc146818rtc.c'))