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Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.99.2 #2 (Red Hat Linux)) id 1xBweo-0000000429a-1Wjy for linux-arm-kernel@lists.infradead.org; Wed, 30 Sep 2026 15:55:48 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A554C2F; Wed, 30 Sep 2026 08:55:39 -0700 (PDT) Received: from [10.57.9.178] (unknown [10.57.9.178]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ADFAF3F86F; Wed, 30 Sep 2026 08:55:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1790783743; bh=Bc5mWey1FMzal2RQfaDFWEDiyRbRNQu+XKVSnU+udT4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=pTyBwWCdjrYPTJJSYO92B4a1mS3MpLniYzgmdympuLvTm1K6xYAkgDEYfr1yvjVgt q/y+ffzRccdbw11Z4sxKlJWU2Z8rQwyBLJiTwd+lucIgdcuxmmZI6Y/vMdyE6KYcHB 0dgbg4WFuEyRcOmFkUu0RPcCwQ1GUN6EPm+GPTis= Message-ID: <210c0b27-c7cb-447a-b6ee-bf6b3fb63acc@arm.com> Date: Wed, 30 Sep 2026 16:55:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v20 6/9] firmware: arm_rmm: Ensure the RMM has GPT entries for memory Content-Language: en-GB To: Sudeep Holla Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, 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, gshan@redhat.com, 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, jonathan.cameron@oss.qualcomm.com References: <20260929221623.1342076-1-suzuki.poulose@arm.com> <20260929221623.1342076-7-suzuki.poulose@arm.com> <20260930-judicious-loris-of-will-dea0a3@sudeepholla> From: Suzuki K Poulose In-Reply-To: <20260930-judicious-loris-of-will-dea0a3@sudeepholla> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260930_165546_816183_B52BF1B4 X-CRM114-Status: GOOD ( 27.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Sudeep On 30/09/2026 15:44, Sudeep Holla wrote: > On Tue, Sep 29, 2026 at 11:16:20PM +0100, Suzuki K Poulose wrote: >> From: Steven Price >> >> The RMM maintains the state of all the granules in the system to make >> sure that the host is abiding by the rules. This state can be maintained >> at different granularity, per page (TRACKING_FINE) or per region >> (TRACKING_COARSE or TRACKING_INTERMEDIATE). The region size depends on the >> underlying "RMI_GRANULE_SIZE". For a "coarse"/"intermediate" region, >> all pages in the region must be of the same state, this implies we need to >> have "fine" tracking for DRAM, so that we can delegate individual pages. >> >> For now we only support a statically carved out memory for tracking >> granules for the "fine" regions. This can be extended in the future to >> allow modifying the tracking granularity and remove the need for a >> static allocation by the firmware. >> >> Similarly, the firmware may create L0 GPT entries describing the total >> address space. But if we change the "PAS" (Physical Address Space) of a >> granule, then the firmware may need to create L1 tables to track the PAS >> at a finer granularity. Linux therefore checks if the platform firmware >> manages the PAR region. i.e., the firmware is in charge of managing the >> L1 GPTs (creation and the required memory for the GPT tables - via static >> carveouts) without host intervention. Support for dynamic GPT creation by >> the host will be added later. >> >> If the firmware requires us to manage the tracking or GPT memory, >> deactivate the RMM and reclaim any memory donated at RMM activation. >> >> Apply the same checks when hotplugged memory is brought online. >> ... >> --- >> drivers/firmware/arm_rmm/rmi.c | 247 ++++++++++++++++++++++++++++++++- >> include/linux/arm-rmi-cmds.h | 18 +++ >> 2 files changed, 264 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/firmware/arm_rmm/rmi.c b/drivers/firmware/arm_rmm/rmi.c >> index d982cf158f8da..d4d098448e46e 100644 >> --- a/drivers/firmware/arm_rmm/rmi.c >> +++ b/drivers/firmware/arm_rmm/rmi.c > > [...] > >> +static int rmi_verify_gpt_firmware_managed(phys_addr_t start, phys_addr_t end) >> +{ >> + unsigned long l0gpt_sz; >> + unsigned long next, par_state; >> + >> + l0gpt_sz = 1UL << (30 + FIELD_GET(RMI_FEATURE_REGISTER_1_L0GPTSZ, >> + rmi_feat_reg(1))); >> + start = ALIGN_DOWN(start, l0gpt_sz); >> + end = ALIGN(end, l0gpt_sz); >> + > > Is it guaranteed that end with not be = PASZ ? The spec says RMI_GPT_INFO > will return RMI_GPT_INFO when top >= pasz. Unlike start, end for good > reason is aligned up(ceil) instead of aligned down, but that also means > end will become PASZ when we reach end of memory, no ? Good point. The RMM spec needs to be fixed to make the condition top > pasz as the top, is really the top the region and is not inclusive. This is already a known issue, tracked by FENIMORE-1807. The proposed fix is : pre: UInt(top) > rmm.static.pasz > > Sorry if I am missing something, trying to understand bits and piece of > RME still, just getting started. Thanks for looking ! Cheers Suzuki > >> + while (start < end) { >> + long ret = rmi_gpt_info(start, end, &next, &par_state); >> + >> + if (ret != RMI_SUCCESS) { >> + pr_err("RMI_GPT_INFO failed for %llx-%llx: (%ld)\n", >> + start, end, ret); >> + return -ENXIO; >> + } >> + >> + if (WARN_ON(next <= start)) >> + return -ENXIO; >> + >> + if (par_state != RMI_GPT_PAR_PLAT) { >> + pr_err("GPT for the region is not managed by firmware %llx-%lx\n", >> + start, next); >> + return -ENODEV; >> + } >> + start = next; >> + } >> + >> + return 0; >> +} >> + >