From: Alexandru Elisei <alexandru.elisei@arm.com> To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, drjones@redhat.com Cc: eric.auger@redhat.com, andre.przywara@arm.com Subject: [kvm-unit-tests PATCH 04/10] arm/arm64: gic: Remove unnecessary synchronization with stats_reset() Date: Wed, 25 Nov 2020 15:51:07 +0000 [thread overview] Message-ID: <20201125155113.192079-5-alexandru.elisei@arm.com> (raw) In-Reply-To: <20201125155113.192079-1-alexandru.elisei@arm.com> The GICv3 driver executes a DSB barrier before sending an IPI, which ensures that memory accesses have completed. This removes the need to enforce ordering with respect to stats_reset() in the IPI handler. For GICv2, we still need the DMB to ensure ordering between the read of the GICC_IAR MMIO register and the read from the acked array. It also matches what the Linux GICv2 driver does in gic_handle_irq(). Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- arm/gic.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arm/gic.c b/arm/gic.c index 4e947e8516a2..7befda2a8673 100644 --- a/arm/gic.c +++ b/arm/gic.c @@ -60,7 +60,6 @@ static void stats_reset(void) bad_sender[i] = -1; bad_irq[i] = -1; } - smp_wmb(); } static void check_acked(const char *testname, cpumask_t *mask) @@ -150,7 +149,13 @@ static void ipi_handler(struct pt_regs *regs __unused) if (irqnr != GICC_INT_SPURIOUS) { gic_write_eoir(irqstat); - smp_rmb(); /* pairs with wmb in stats_reset */ + /* + * Make sure data written before the IPI was triggered is + * observed after the IAR is read. Pairs with the smp_wmb + * when sending the IPI. + */ + if (gic_version() == 2) + smp_rmb(); ++acked[smp_processor_id()]; check_ipi_sender(irqstat); check_irqnr(irqnr); -- 2.29.2
WARNING: multiple messages have this Message-ID (diff)
From: Alexandru Elisei <alexandru.elisei@arm.com> To: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, drjones@redhat.com Cc: andre.przywara@arm.com Subject: [kvm-unit-tests PATCH 04/10] arm/arm64: gic: Remove unnecessary synchronization with stats_reset() Date: Wed, 25 Nov 2020 15:51:07 +0000 [thread overview] Message-ID: <20201125155113.192079-5-alexandru.elisei@arm.com> (raw) In-Reply-To: <20201125155113.192079-1-alexandru.elisei@arm.com> The GICv3 driver executes a DSB barrier before sending an IPI, which ensures that memory accesses have completed. This removes the need to enforce ordering with respect to stats_reset() in the IPI handler. For GICv2, we still need the DMB to ensure ordering between the read of the GICC_IAR MMIO register and the read from the acked array. It also matches what the Linux GICv2 driver does in gic_handle_irq(). Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com> --- arm/gic.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arm/gic.c b/arm/gic.c index 4e947e8516a2..7befda2a8673 100644 --- a/arm/gic.c +++ b/arm/gic.c @@ -60,7 +60,6 @@ static void stats_reset(void) bad_sender[i] = -1; bad_irq[i] = -1; } - smp_wmb(); } static void check_acked(const char *testname, cpumask_t *mask) @@ -150,7 +149,13 @@ static void ipi_handler(struct pt_regs *regs __unused) if (irqnr != GICC_INT_SPURIOUS) { gic_write_eoir(irqstat); - smp_rmb(); /* pairs with wmb in stats_reset */ + /* + * Make sure data written before the IPI was triggered is + * observed after the IAR is read. Pairs with the smp_wmb + * when sending the IPI. + */ + if (gic_version() == 2) + smp_rmb(); ++acked[smp_processor_id()]; check_ipi_sender(irqstat); check_irqnr(irqnr); -- 2.29.2 _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply other threads:[~2020-11-25 15:50 UTC|newest] Thread overview: 78+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-25 15:51 [kvm-unit-tests PATCH 00/10] GIC fixes and improvements Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-11-25 15:51 ` [kvm-unit-tests PATCH 01/10] lib: arm/arm64: gicv3: Add missing barrier when sending IPIs Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-01 16:37 ` Auger Eric 2020-12-01 16:37 ` Auger Eric 2020-12-01 17:37 ` Alexandru Elisei 2020-12-01 17:37 ` Alexandru Elisei 2020-11-25 15:51 ` [kvm-unit-tests PATCH 02/10] lib: arm/arm64: gicv2: " Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-01 16:37 ` Auger Eric 2020-12-01 16:37 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 03/10] arm/arm64: gic: Remove memory synchronization from ipi_clear_active_handler() Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-01 16:37 ` Auger Eric 2020-12-01 16:37 ` Auger Eric 2020-12-02 14:02 ` Alexandru Elisei 2020-12-02 14:02 ` Alexandru Elisei 2020-12-02 14:14 ` Alexandru Elisei 2020-12-02 14:14 ` Alexandru Elisei 2020-12-03 9:41 ` Auger Eric 2020-12-03 9:41 ` Auger Eric 2020-11-25 15:51 ` Alexandru Elisei [this message] 2020-11-25 15:51 ` [kvm-unit-tests PATCH 04/10] arm/arm64: gic: Remove unnecessary synchronization with stats_reset() Alexandru Elisei 2020-12-01 16:48 ` Auger Eric 2020-12-01 16:48 ` Auger Eric 2020-12-02 14:06 ` Alexandru Elisei 2020-12-02 14:06 ` Alexandru Elisei 2020-12-03 13:10 ` Auger Eric 2020-12-03 13:10 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 05/10] arm/arm64: gic: Use correct memory ordering for the IPI test Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-03 13:10 ` Auger Eric 2020-12-03 13:10 ` Auger Eric 2020-12-03 13:21 ` Alexandru Elisei 2020-12-03 13:21 ` Alexandru Elisei 2020-11-25 15:51 ` [kvm-unit-tests PATCH 06/10] arm/arm64: gic: Check spurious and bad_sender in the active test Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-03 13:10 ` Auger Eric 2020-12-03 13:10 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 07/10] arm/arm64: gic: Wait for writes to acked or spurious to complete Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-03 13:21 ` Auger Eric 2020-12-03 13:21 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 08/10] arm/arm64: gic: Split check_acked() into two functions Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-03 13:39 ` Auger Eric 2020-12-03 13:39 ` Auger Eric 2020-12-10 14:45 ` Alexandru Elisei 2020-12-10 14:45 ` Alexandru Elisei 2020-12-15 13:58 ` Auger Eric 2020-12-15 13:58 ` Auger Eric 2020-12-16 11:40 ` Alexandru Elisei 2020-12-16 11:40 ` Alexandru Elisei 2020-12-16 12:37 ` Auger Eric 2020-12-16 12:37 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 09/10] arm/arm64: gic: Make check_acked() more generic Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-12-03 14:59 ` Auger Eric 2020-12-03 14:59 ` Auger Eric 2020-11-25 15:51 ` [kvm-unit-tests PATCH 10/10] arm64: gic: Use IPI test checking for the LPI tests Alexandru Elisei 2020-11-25 15:51 ` Alexandru Elisei 2020-11-26 9:30 ` Zenghui Yu 2020-11-26 9:30 ` Zenghui Yu 2020-11-27 14:50 ` Alexandru Elisei 2020-11-27 14:50 ` Alexandru Elisei 2020-11-30 13:59 ` Zenghui Yu 2020-11-30 13:59 ` Zenghui Yu 2020-11-30 14:19 ` Alexandru Elisei 2020-11-30 14:19 ` Alexandru Elisei 2020-12-01 15:09 ` Alexandru Elisei 2020-12-01 15:09 ` Alexandru Elisei 2020-11-30 17:48 ` Auger Eric 2020-11-30 17:48 ` Auger Eric 2020-12-03 14:59 ` Auger Eric 2020-12-03 14:59 ` Auger Eric 2020-12-09 10:29 ` Alexandru Elisei 2020-12-09 10:29 ` Alexandru Elisei
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