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[175.34.8.244]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2bd5bd5ef1bsm293727375ad.4.2026.05.20.17.51.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 May 2026 17:52:08 -0700 (PDT) Message-ID: <45a953a8-6edc-45c3-b5bd-17f14397ab89@redhat.com> Date: Thu, 21 May 2026 10:51:56 +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 v14 07/44] arm64: RMI: Configure the RMM with the host's page size To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , Suzuki K Poulose , Zenghui Yu , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Joey Gouly , Alexandru Elisei , Christoffer Dall , Fuad Tabba , linux-coco@lists.linux.dev, Ganapatrao Kulkarni , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" , Emi Kisanuki , Vishal Annapurve , WeiLin.Chang@arm.com, Lorenzo.Pieralisi2@arm.com References: <20260513131757.116630-1-steven.price@arm.com> <20260513131757.116630-8-steven.price@arm.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20260513131757.116630-8-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Steven, On 5/13/26 11:17 PM, Steven Price wrote: > 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 granulatity > equal to PAGE_SIZE. > > Signed-off-by: Steven Price > --- > Changes since v13: > * Moved out of KVM. > --- > arch/arm64/kernel/rmi.c | 42 +++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 42 insertions(+) > > diff --git a/arch/arm64/kernel/rmi.c b/arch/arm64/kernel/rmi.c > index 99c1ccc35c11..a14ead5dedda 100644 > --- a/arch/arm64/kernel/rmi.c > +++ b/arch/arm64/kernel/rmi.c > @@ -49,6 +49,45 @@ static int rmi_check_version(void) > return 0; > } > > +static int rmi_configure(void) > +{ > + struct rmm_config *config __free(free_page) = NULL; > + unsigned long ret; > + > + config = (struct rmm_config *)get_zeroed_page(GFP_KERNEL); > + if (!config) > + return -ENOMEM; > + > + switch (PAGE_SIZE) { > + case SZ_4K: > + config->rmi_granule_size = RMI_GRANULE_SIZE_4KB; > + break; > + case SZ_16K: > + config->rmi_granule_size = RMI_GRANULE_SIZE_16KB; > + break; > + case SZ_64K: > + config->rmi_granule_size = RMI_GRANULE_SIZE_64KB; > + break; > + default: > + pr_err("Unsupported PAGE_SIZE for RMM\n"); > + return -EINVAL; > + } > + > + ret = rmi_rmm_config_set(virt_to_phys(config)); > + if (ret) { > + pr_err("RMM config set failed\n"); > + return -EINVAL; > + } > + Looking at branch 'topics/rmm-v2.0-poc_2' of RMM implementation, the granule size is fixed to be 4KB at present. I'm not sure if I have looked into correct RMM implementation, but 'topics/rmm-v2.0-poc_2' is recommended one in the cover letter. Besides, there has checks in the handler of the RMI command to make sure that struct rmm_config::tracking_region_size to be 1GB, indicated by zero. It maybe worthy to set it before call to rmi_rmm_config_set(). config.tracking_region_size = 0; /* 1GB */ ret = rmi_rmm_config_set(virt_to_phys(config)); > + ret = rmi_rmm_activate(); > + if (ret) { > + pr_err("RMM activate failed\n"); > + return -ENXIO; > + } > + > + return 0; > +} > + > static int __init arm64_init_rmi(void) > { > /* Continue without realm support if we can't agree on a version */ > @@ -60,6 +99,9 @@ static int __init arm64_init_rmi(void) > if (WARN_ON(rmi_features(1, &rmm_feat_reg1))) > return 0; > > + if (rmi_configure()) > + return 0; > + > return 0; > } > subsys_initcall(arm64_init_rmi); Thanks, Gavin