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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39b08bcc081sm30955490a91.6.2026.09.08.00.04.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Sep 2026 00:04:19 -0700 (PDT) Message-ID: <10893135-4757-44de-91b5-180a9774d868@redhat.com> Date: Tue, 8 Sep 2026 17:04:08 +1000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v17 3/7] firmware: arm_rmm: Configure the RMM with the host's page size To: Suzuki K Poulose , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: maz@kernel.org, will@kernel.org, catalin.marinas@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, steven.price@arm.com, aneesh.kumar@kernel.org, oupton@kernel.org, joey.gouly@arm.com, tabba@google.com, yuzenghui@huawei.com, linux-coco@lists.linux.dev, gankulkarni@os.amperecomputing.com, sdonthineni@nvidia.com, alpergun@google.com, fj0570is@fujitsu.com, WeiLin.Chang@arm.com, lpieralisi@kernel.org, enju.kohei@fujitsu.com References: <20260907095942.1140734-1-suzuki.poulose@arm.com> <20260907095942.1140734-4-suzuki.poulose@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20260907095942.1140734-4-suzuki.poulose@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Suzuki, On 9/7/26 7:59 PM, Suzuki K Poulose wrote: > From: Steven Price > > RMM v2.0 brings the ability to set the RMM's granule size. Check the > feature registers and configure the RMM so that it matches the host's > page size. This means that operations can be done with a granularity > equal to PAGE_SIZE. > > Signed-off-by: Steven Price > Signed-off-by: Suzuki K Poulose > --- > Changes since v15: > * Actually check the feature register for the host's page-size support. > Changes since v14: > * Move the implementation into drivers/firmware/arm_rmm. > Changes since v13: > * Moved out of KVM. > --- > drivers/firmware/arm_rmm/rmi.c | 58 ++++++++++++++++++++++++++++++++++ > include/linux/arm-rmi-cmds.h | 17 ++++++++++ > 2 files changed, 75 insertions(+) > > diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/arm_rmm/rmi.c > index 008a783407b4e..76f91c145e1fd 100644 > --- a/drivers/firmware/arm_rmm/rmi.c > +++ b/drivers/firmware/arm_rmm/rmi.c > @@ -77,6 +77,60 @@ static int rmi_read_features(void) > return 0; > } > > +static int rmi_configure(void) > +{ > + unsigned long granule_feature; > + unsigned long granule_size; > + int ret = 0; > + struct rmm_config *config; > + > + switch (PAGE_SIZE) { > + case SZ_4K: > + granule_size = RMI_GRANULE_SIZE_4KB; > + granule_feature = RMI_FEATURE_REGISTER_1_RMI_GRAN_SZ_4KB; > + break; > + case SZ_16K: > + granule_size = RMI_GRANULE_SIZE_16KB; > + granule_feature = RMI_FEATURE_REGISTER_1_RMI_GRAN_SZ_16KB; > + break; > + case SZ_64K: > + granule_size = RMI_GRANULE_SIZE_64KB; > + granule_feature = RMI_FEATURE_REGISTER_1_RMI_GRAN_SZ_64KB; > + break; > + default: > + BUILD_BUG(); > + } > + > + if (!(rmi_feat_reg(1) & granule_feature)) { > + pr_err("RMM does not support %luKB granules\n", > + PAGE_SIZE >> 10); > + return -ENXIO; > + } > + > + config = (struct rmm_config *)get_zeroed_page(GFP_KERNEL); > + if (!config) > + return -ENOMEM; An error message is needed here. if (!config) { pr_err("Unable to alloc RMM config memory\n"); return -ENOMEM; } > + > + config->rmi_granule_size = granule_size; > + > + /* > + * For now we set the tracking_region_size to 0 which is the only option > + * for 4KB PAGE_SIZE (1GB for 4KB PAGE_SIZE, 32MB/512MB for 16KB/64KB). > + * TODO: Support other tracking sizes via Kconfig option for other > + * PAGE_SIZES > + */ > + config->tracking_region_size = 0; > + > + ret = rmi_rmm_config_set(virt_to_phys(config)); > + if (ret) { > + pr_err("RMM config set failed\n"); > + ret = -EINVAL; > + } The error code from rmi_rmm_config_set() is indicative sometimes. Also, -ENXIO would be more appropriate than -EINVAL? if (ret) { pr_err("RMM config set failed (%d)\n", ret); ret = -ENXIO; } > + > + free_page((unsigned long)config); > + return ret; > +} > + > static int __init arm64_init_rmi(void) > { > int ret; > @@ -90,6 +144,10 @@ static int __init arm64_init_rmi(void) > if (ret) > return ret; > > + ret = rmi_configure(); > + if (ret) > + return ret; > + > return 0; > } > > diff --git a/include/linux/arm-rmi-cmds.h b/include/linux/arm-rmi-cmds.h > index 2fb1f7f86d71e..9aa27697e2377 100644 > --- a/include/linux/arm-rmi-cmds.h > +++ b/include/linux/arm-rmi-cmds.h > @@ -12,6 +12,23 @@ > > unsigned long rmi_feat_reg(unsigned long id); > > +/** > + * rmi_rmm_config_set() - Configure the RMM > + * @cfg_ptr: PA of a struct rmm_config > + * > + * Sets configuration options on the RMM. > + * > + * Return: RMI return code > + */ > +static inline int rmi_rmm_config_set(unsigned long cfg_ptr) > +{ > + struct arm_smccc_res res; > + > + arm_smccc_1_1_invoke(SMC_RMI_RMM_CONFIG_SET, cfg_ptr, &res); > + > + return res.a0; > +} > + rmi_rmm_config_set() is used for once by rmi.c::rmi_configure(), I would not expose rmi_rmm_config_set() by combining the logic to rmi.c::rmi_configure(). > /** > * rmi_features() - Read feature register > * @index: Feature register index Thanks, Gavin