From: Gavin Shan <gshan@redhat.com>
To: Jinjie Ruan <ruanjinjie@huawei.com>,
james.morse@arm.com, ben.horgan@arm.com,
reinette.chatre@intel.com, fenghuay@nvidia.com,
zengheng4@huawei.com, tan.shaopeng@jp.fujitsu.com,
jic23@kernel.org, linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 1/3] arm_mpam: resctrl: Leave CDP off when there are too few PARTIDs
Date: Fri, 13 Nov 2026 09:28:34 +1000 [thread overview]
Message-ID: <8804ae3a-8dac-4f4a-98b5-06b2a7524d12@redhat.com> (raw)
In-Reply-To: <20261111081316.3828283-2-ruanjinjie@huawei.com>
On 11/11/26 6:13 PM, Jinjie Ruan wrote:
> Enabling CDP requires at least 2 PARTIDs. If there are too few PARTIDs,
> resctrl_arch_set_cdp_enabled() returns -EINVAL, but only after it has
> recorded CDP as enabled, halved the monitor count and turned off the
> mbw_max MBA control. resctrl then believes CDP is off, which leaves the
> two sides out of step and the halved monitor count and the missing MBA
> control are not undone.
>
> Check the PARTID limit before anything is changed so a failed enable has
> no effect.
>
> Fixes: 6789fb99282c ("arm_mpam: resctrl: Add CDP emulation")
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> Cc: <stable@vger.kernel.org> # 7.1+
> ---
> drivers/resctrl/mpam_resctrl.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
Reviewed-by: Gavin Shan <gshan@redhat.com>
next prev parent reply other threads:[~2026-11-12 23:28 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-11 8:13 [PATCH v4 0/3] arm_mpam: resctrl: Fix several CDP bugs Jinjie Ruan
2026-11-11 8:13 ` [PATCH v4 1/3] arm_mpam: resctrl: Leave CDP off when there are too few PARTIDs Jinjie Ruan
2026-11-12 23:28 ` Gavin Shan [this message]
2026-11-11 8:13 ` [PATCH v4 2/3] arm_mpam: resctrl: Only enable CDP on a resource that supports it Jinjie Ruan
2026-11-12 23:42 ` Gavin Shan
2026-11-11 8:13 ` [PATCH v4 3/3] arm_mpam: resctrl: Limit num_rmids to the CLOSIDs in use Jinjie Ruan
2026-11-12 23:46 ` Gavin Shan
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