From: Marc Zyngier <maz@kernel.org>
To: Alexandru Elisei <alexandru.elisei@arm.com>
Cc: Eric Auger <eric.auger@redhat.com>,
eric.auger.pro@gmail.com, kvm@vger.kernel.org,
kvmarm@lists.linux.dev, andrew.jones@linux.dev, will@kernel.org,
oliver.upton@linux.dev, ricarkol@google.com, reijiw@google.com
Subject: Re: [kvm-unit-tests PATCH 4/6] arm: pmu: Fix chain counter enable/disable sequences
Date: Fri, 21 Apr 2023 12:24:51 +0100 [thread overview]
Message-ID: <651289b765b20d6e2dc32f71c5d7b5b5@kernel.org> (raw)
In-Reply-To: <ZEJq_XNHi8Mx3CBy@monolith.localdoman>
On 2023-04-21 11:52, Alexandru Elisei wrote:
> Hi,
>
> On Wed, Mar 15, 2023 at 12:07:23PM +0100, Eric Auger wrote:
>> In some ARM ARM ddi0487 revisions it is said that
>> disabling/enabling a pair of counters that are paired
>> by a CHAIN event should follow a given sequence:
>>
>> Disable the low counter first, isb, disable the high counter
>> Enable the high counter first, isb, enable low counter
>>
>> This was the case in Fc. However this is not written anymore
>> in Ia revision.
>>
>> Introduce 2 helpers to execute those sequences and replace
>> the existing PMCNTENCLR/ENSET calls.
>>
>> Also fix 2 write_sysreg_s(0x0, PMCNTENSET_EL0) in subtest 5 & 6
>> and replace them by PMCNTENCLR writes since writing 0 in
>> PMCNTENSET_EL0 has no effect.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>> ---
>> arm/pmu.c | 37 ++++++++++++++++++++++++++++---------
>> 1 file changed, 28 insertions(+), 9 deletions(-)
>>
>> diff --git a/arm/pmu.c b/arm/pmu.c
>> index dde399e2..af679667 100644
>> --- a/arm/pmu.c
>> +++ b/arm/pmu.c
>> @@ -730,6 +730,22 @@ static void test_chained_sw_incr(bool unused)
>> read_regn_el0(pmevcntr, 0), \
>> read_sysreg(pmovsclr_el0))
>>
>> +static void enable_chain_counter(int even)
>> +{
>> + write_sysreg_s(BIT(even), PMCNTENSET_EL0); /* Enable the high
>> counter first */
>> + isb();
>> + write_sysreg_s(BIT(even + 1), PMCNTENSET_EL0); /* Enable the low
>> counter */
>> + isb();
>> +}
>
> In ARM DDI 0487F.b, at the bottom of page D7-2727:
>
> "When enabling a pair of counters that are paired by a CHAIN event,
> software must:
>
> 1. Enable the high counter, by setting PMCNTENCLR_EL0[n+1] to 0 and, if
> necessary, setting PMCR_EL0.E to 1.
> 2. Execute an ISB instruction, or perform another Context
> synchronization
> event.
> 3. Enable the low counter by setting PMCNTENCLR_EL0[n] to 0."
This particular text seems to have been removed from the H.a and I.a
revisions of the ARM ARM, and I cannot spot any equivalent requirement.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2023-04-21 11:24 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-15 11:07 [kvm-unit-tests PATCH 0/6] arm: pmu: Fix random failures of pmu-chain-promotion Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 1/6] arm: pmu: pmu-chain-promotion: Improve debug messages Eric Auger
2023-04-21 9:25 ` Alexandru Elisei
2023-04-24 20:09 ` Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 2/6] arm: pmu: pmu-chain-promotion: Introduce defines for count and margin values Eric Auger
2023-04-21 9:55 ` Alexandru Elisei
2023-04-24 20:09 ` Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 3/6] arm: pmu: Add extra DSB barriers in the mem_access loop Eric Auger
2023-04-21 10:25 ` Alexandru Elisei
2023-04-24 20:11 ` Eric Auger
2023-04-25 13:00 ` Alexandru Elisei
2023-05-31 20:14 ` Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 4/6] arm: pmu: Fix chain counter enable/disable sequences Eric Auger
2023-04-21 10:52 ` Alexandru Elisei
2023-04-21 11:24 ` Marc Zyngier [this message]
2023-05-31 20:15 ` Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 5/6] arm: pmu: Add pmu-memaccess-reliability test Eric Auger
2023-04-21 11:13 ` Alexandru Elisei
2023-05-31 20:15 ` Eric Auger
2023-03-15 11:07 ` [kvm-unit-tests PATCH 6/6] arm: pmu-chain-promotion: Increase the count and margin values Eric Auger
2023-04-04 6:23 ` [kvm-unit-tests PATCH 0/6] arm: pmu: Fix random failures of pmu-chain-promotion Eric Auger
2023-04-04 12:47 ` Andrew Jones
2023-04-12 7:34 ` Andrew Jones
2023-04-12 8:55 ` Alexandru Elisei
2023-04-12 8:47 ` Mark Rutland
2023-04-19 7:32 ` Eric Auger
2023-04-19 9:39 ` Alexandru Elisei
2023-04-21 8:11 ` Eric Auger
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