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From: Alexandru Elisei <alexandru.elisei@arm.com>
To: drjones@redhat.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: andre.przywara@arm.com, eric.auger@redhat.com, yuzenghui@huawei.com
Subject: [kvm-unit-tests PATCH v2 03/12] arm/arm64: gic: Remove SMP synchronization from ipi_clear_active_handler()
Date: Thu, 17 Dec 2020 14:13:51 +0000	[thread overview]
Message-ID: <20201217141400.106137-4-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20201217141400.106137-1-alexandru.elisei@arm.com>

The gicv{2,3}-active test sends an IPI from the boot CPU to itself, then
checks that the interrupt has been received as expected. There is no need
to use inter-processor memory synchronization primitives on code that runs
on the same CPU, so remove the unneeded memory barriers.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arm/gic.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arm/gic.c b/arm/gic.c
index ca61dba2986c..1c9f4a01b6e4 100644
--- a/arm/gic.c
+++ b/arm/gic.c
@@ -364,6 +364,7 @@ static struct gic gicv3 = {
 	},
 };
 
+/* Runs on the same CPU as the sender, no need for memory synchronization */
 static void ipi_clear_active_handler(struct pt_regs *regs __unused)
 {
 	u32 irqstat = gic_read_iar();
@@ -380,13 +381,10 @@ static void ipi_clear_active_handler(struct pt_regs *regs __unused)
 
 		writel(val, base + GICD_ICACTIVER);
 
-		smp_rmb(); /* pairs with wmb in stats_reset */
 		++acked[smp_processor_id()];
 		check_irqnr(irqnr);
-		smp_wmb(); /* pairs with rmb in check_acked */
 	} else {
 		++spurious[smp_processor_id()];
-		smp_wmb();
 	}
 }
 
-- 
2.29.2


WARNING: multiple messages have this Message-ID (diff)
From: Alexandru Elisei <alexandru.elisei@arm.com>
To: drjones@redhat.com, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu
Cc: andre.przywara@arm.com
Subject: [kvm-unit-tests PATCH v2 03/12] arm/arm64: gic: Remove SMP synchronization from ipi_clear_active_handler()
Date: Thu, 17 Dec 2020 14:13:51 +0000	[thread overview]
Message-ID: <20201217141400.106137-4-alexandru.elisei@arm.com> (raw)
In-Reply-To: <20201217141400.106137-1-alexandru.elisei@arm.com>

The gicv{2,3}-active test sends an IPI from the boot CPU to itself, then
checks that the interrupt has been received as expected. There is no need
to use inter-processor memory synchronization primitives on code that runs
on the same CPU, so remove the unneeded memory barriers.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
---
 arm/gic.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/arm/gic.c b/arm/gic.c
index ca61dba2986c..1c9f4a01b6e4 100644
--- a/arm/gic.c
+++ b/arm/gic.c
@@ -364,6 +364,7 @@ static struct gic gicv3 = {
 	},
 };
 
+/* Runs on the same CPU as the sender, no need for memory synchronization */
 static void ipi_clear_active_handler(struct pt_regs *regs __unused)
 {
 	u32 irqstat = gic_read_iar();
@@ -380,13 +381,10 @@ static void ipi_clear_active_handler(struct pt_regs *regs __unused)
 
 		writel(val, base + GICD_ICACTIVER);
 
-		smp_rmb(); /* pairs with wmb in stats_reset */
 		++acked[smp_processor_id()];
 		check_irqnr(irqnr);
-		smp_wmb(); /* pairs with rmb in check_acked */
 	} else {
 		++spurious[smp_processor_id()];
-		smp_wmb();
 	}
 }
 
-- 
2.29.2

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  parent reply	other threads:[~2020-12-17 14:15 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-17 14:13 [kvm-unit-tests PATCH v2 00/12] GIC fixes and improvements Alexandru Elisei
2020-12-17 14:13 ` Alexandru Elisei
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 01/12] lib: arm/arm64: gicv3: Add missing barrier when sending IPIs Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 12:03   ` André Przywara
2020-12-18 12:03     ` André Przywara
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 02/12] lib: arm/arm64: gicv2: " Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-17 14:13 ` Alexandru Elisei [this message]
2020-12-17 14:13   ` [kvm-unit-tests PATCH v2 03/12] arm/arm64: gic: Remove SMP synchronization from ipi_clear_active_handler() Alexandru Elisei
2020-12-18 12:04   ` André Przywara
2020-12-18 12:04     ` André Przywara
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 04/12] arm/arm64: gic: Remove unnecessary synchronization with stats_reset() Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 05/12] arm/arm64: gic: Use correct memory ordering for the IPI test Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 12:04   ` André Przywara
2020-12-18 12:04     ` André Przywara
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 06/12] arm/arm64: gic: Check spurious and bad_sender in the active test Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 07/12] arm/arm64: gic: Wait for writes to acked or spurious to complete Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 08/12] arm/arm64: gic: Split check_acked() into two functions Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 15:52   ` André Przywara
2020-12-18 15:52     ` André Przywara
2021-01-25 17:27     ` Alexandru Elisei
2021-01-25 17:27       ` Alexandru Elisei
2021-01-27 15:10       ` Andre Przywara
2021-01-27 15:10         ` Andre Przywara
2021-01-27 16:00         ` Alexandru Elisei
2021-01-27 16:00           ` Alexandru Elisei
2021-02-16 18:04           ` Andre Przywara
2021-02-16 18:04             ` Andre Przywara
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 09/12] arm/arm64: gic: Make check_acked() more generic Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 15:52   ` André Przywara
2020-12-18 15:52     ` André Przywara
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 10/12] arm64: gic: its-trigger: Don't trigger the LPI while it is pending Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 18:15   ` André Przywara
2020-12-18 18:15     ` André Przywara
2021-01-25 16:57     ` Alexandru Elisei
2021-01-25 16:57       ` Alexandru Elisei
2020-12-17 14:13 ` [kvm-unit-tests PATCH v2 11/12] lib: arm64: gic-v3-its: Add wmb() barrier before INT command Alexandru Elisei
2020-12-17 14:13   ` Alexandru Elisei
2020-12-18 18:36   ` André Przywara
2020-12-18 18:36     ` André Przywara
2021-01-25 15:16     ` Alexandru Elisei
2021-01-25 15:16       ` Alexandru Elisei
2020-12-17 14:14 ` [kvm-unit-tests PATCH v2 12/12] arm64: gic: Use IPI test checking for the LPI tests Alexandru Elisei
2020-12-17 14:14   ` Alexandru Elisei

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