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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b503191a43sm1796185c88.10.2026.11.12.15.28.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 12 Nov 2026 15:28:39 -0800 (PST) Message-ID: <8804ae3a-8dac-4f4a-98b5-06b2a7524d12@redhat.com> Date: Fri, 13 Nov 2026 09:28:34 +1000 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 1/3] arm_mpam: resctrl: Leave CDP off when there are too few PARTIDs To: Jinjie Ruan , 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 References: <20261111081316.3828283-1-ruanjinjie@huawei.com> <20261111081316.3828283-2-ruanjinjie@huawei.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20261111081316.3828283-2-ruanjinjie@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 > Cc: # 7.1+ > --- > drivers/resctrl/mpam_resctrl.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > Reviewed-by: Gavin Shan