From: Auger Eric <eric.auger@redhat.com>
To: Alexandru Elisei <alexandru.elisei@arm.com>,
kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu,
drjones@redhat.com
Cc: andre.przywara@arm.com
Subject: Re: [kvm-unit-tests PATCH 04/10] arm/arm64: gic: Remove unnecessary synchronization with stats_reset()
Date: Thu, 3 Dec 2020 14:10:05 +0100 [thread overview]
Message-ID: <46af2717-6da7-3ea1-5ac0-1283b1d842cf@redhat.com> (raw)
In-Reply-To: <20201125155113.192079-5-alexandru.elisei@arm.com>
Hi,
On 11/25/20 4:51 PM, Alexandru Elisei wrote:
> 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>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Eric
> ---
> 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);
>
next prev parent reply other threads:[~2020-12-03 13:11 UTC|newest]
Thread overview: 39+ 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 ` [kvm-unit-tests PATCH 01/10] lib: arm/arm64: gicv3: Add missing barrier when sending IPIs Alexandru Elisei
2020-12-01 16:37 ` Auger Eric
2020-12-01 17:37 ` Alexandru Elisei
2020-11-25 15:51 ` [kvm-unit-tests PATCH 02/10] lib: arm/arm64: gicv2: " Alexandru Elisei
2020-12-01 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
2020-12-01 16:37 ` Auger Eric
2020-12-02 14:02 ` Alexandru Elisei
2020-12-02 14:14 ` Alexandru Elisei
2020-12-03 9:41 ` Auger Eric
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
2020-12-02 14:06 ` Alexandru Elisei
2020-12-03 13:10 ` Auger Eric [this message]
2020-11-25 15:51 ` [kvm-unit-tests PATCH 05/10] arm/arm64: gic: Use correct memory ordering for the IPI test Alexandru Elisei
2020-12-03 13:10 ` Auger Eric
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
2020-12-03 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
2020-12-03 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
2020-12-03 13:39 ` Auger Eric
2020-12-10 14:45 ` Alexandru Elisei
2020-12-15 13:58 ` Auger Eric
2020-12-16 11:40 ` Alexandru Elisei
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
2020-12-03 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
2020-11-26 9:30 ` Zenghui Yu
2020-11-27 14:50 ` Alexandru Elisei
2020-11-30 13:59 ` Zenghui Yu
2020-11-30 14:19 ` Alexandru Elisei
2020-12-01 15:09 ` Alexandru Elisei
2020-11-30 17:48 ` Auger Eric
2020-12-03 14:59 ` Auger Eric
2020-12-09 10:29 ` Alexandru Elisei
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