From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 3226D46F497; Mon, 14 Sep 2026 14:02:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789394559; cv=none; b=fD+SWYx/I7wDem19nSHdtoIe8ugiP/JRUtYzaeVzVIzUL9VYhzAxe19xkj1rBlzN6vCB1BhBI71M/OzYgCRFmsmoB0B1limweMMuIp3c8asxaSIgYaMzo/+LEBIpjwJ5odzol3F/8QMIJUrQsj0WoCIOOT8ChE4OpdQbWrfQnpA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789394559; c=relaxed/simple; bh=DFYtcB/Oi+25lkKqGHoqBfdSqnw6tByCRDZwTC/jjuI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=MudTkFx9rufgmon/UmKGuSlUhzUB4fPjdrjIsOqZ+/8B2VwUxnO3WVZok/gBw61ZmTttPJELzOqQ4rOkQJC00b1OrP2qPGsP5JY4kqqxsxMhmIh4TtpFebUI1do2cpEPPhKuo3vcK7UDliL9j/R+Yus+xlfAoxuk8pGCb9iArW8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=J2DNkFqm; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="J2DNkFqm" 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 DE99B1570; Mon, 14 Sep 2026 07:02:31 -0700 (PDT) Received: from [10.0.128.139] (unknown [10.0.128.139]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 46F533F882; Mon, 14 Sep 2026 07:02:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1789394555; bh=DFYtcB/Oi+25lkKqGHoqBfdSqnw6tByCRDZwTC/jjuI=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=J2DNkFqmdAiXns7yDGCaFHwY8+MPmxxjgt9Snm1UwvQlYakyn6BB2oxIq1rBTjCIH FdEDRRxKwxS1Jcc6S1Sxuh21VJWfmDFFXBO9vsG8aT15x4/yCn7US+Qkxxo0jiZqy4 Y2hcEdw0cSqvDxWgRPcZlKLynkxxaLcdLy5rGLfY= Message-ID: <657e69c2-d0e9-433a-b0d2-4f16bc94ee2c@arm.com> Date: Mon, 14 Sep 2026 15:02:30 +0100 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 v18 4/7] firmware: arm_rmm: Add support for SRO 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 References: <20260912083611.2513845-1-suzuki.poulose@arm.com> <20260912083611.2513845-5-suzuki.poulose@arm.com> <20260914-talkative-healthy-pogona-334c03@sudeepholla> From: Suzuki K Poulose In-Reply-To: <20260914-talkative-healthy-pogona-334c03@sudeepholla> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 14/09/2026 13:50, Sudeep Holla wrote: > On Sat, Sep 12, 2026 at 09:36:07AM +0100, Suzuki K Poulose wrote: >> RMM v2.0 introduces the concept of "Stateful RMI Operations" (SRO). This >> means that an SMC can return with an operation still in progress. The >> host is expected to continue the operation until it reaches a conclusion >> (either success or failure). During this process the RMM can request >> additional memory ('donate') or hand memory back to the host >> ('reclaim'). The host can request an in progress operation is cancelled, >> but still continue the operation until it has completed (otherwise the >> incomplete operation may cause future RMM operations to fail). >> >> The SRO is tracked using a struct rmi_sro_state object which keeps track >> of any memory which has been allocated but not yet consumed by the RMM >> or reclaimed from the RMM. This allows the memory to be reused in a >> future request within the same operation. It will also permit an >> operation to be done in a context where memory allocation may be >> difficult (e.g. atomic context) with the option to abort the operation >> and retry the memory allocation outside of the atomic context. The >> memory stored in the struct rmi_sro_state object can then be reused on >> the subsequent attempt. >> >> Wrappers for SRO RMI commands are also provided here because they depend >> on the rmi_sro_execute() implementation added by this patch. >> Delegate/undelegate handles are also added here because they now use the >> SRO/stateful command infrastructure and are also used for the memory >> DONATE/RECLAIM flows. >> >> Signed-off-by: Steven Price >> Co-Developed-by: Suzuki K Poulose >> Signed-off-by: Suzuki K Poulose > > [...] > >> +static int rmi_sro_donate_noncontig(struct rmi_sro_state *sro, >> + unsigned long sro_handle, >> + unsigned long donatereq, >> + struct arm_smccc_1_2_regs *out_regs, >> + gfp_t gfp) >> +{ >> + unsigned long block_size_fld = RMI_DONATE_BLOCK_SIZE(donatereq); >> + unsigned long block_size = rmi_addr_block_size_to_bytes(block_size_fld); >> + unsigned long count = RMI_DONATE_COUNT(donatereq); >> + unsigned long state = RMI_DONATE_STATE(donatereq); >> + unsigned long found = 0; >> + unsigned long donated_granules; >> + unsigned long granules_per_block = block_size >> PAGE_SHIFT; >> + unsigned long consumed_blocks; >> + int addr_list_start = sro->addr_count; >> + >> + int ret; >> + >> + for (int i = 0; i < addr_list_start && found < count; i++) { >> + unsigned long entry = sro->addr_list[i]; >> + >> + if (RMI_ADDR_RANGE_BLOCK_SIZE(entry) == block_size_fld && >> + RMI_ADDR_RANGE_COUNT(entry) == 1 && >> + RMI_ADDR_RANGE_STATE(entry) == state) { >> + addr_list_start--; >> + swap(sro->addr_list[addr_list_start], >> + sro->addr_list[i]); >> + found++; >> + i--; >> + } >> + } >> + >> + ret = rmi_sro_ensure_capacity(sro, count - found); >> + if (ret) >> + return ret; >> + >> + while (found < count) { >> + unsigned long addr_range; >> + void *virt = alloc_pages_exact(block_size, gfp); >> + phys_addr_t phys; >> + >> + if (!virt) >> + return -ENOMEM; >> + >> + phys = virt_to_phys(virt); >> + >> + if (state == RMI_OP_MEM_DELEGATED) { > > Based on my understanding, rmi_sro_memxfer_execute() is an exported function > and can be invoked by any module. The donatereq argument appears to accept one > of three operations: > > RMI_OP_MEM_DELEGATED > RMI_OP_MEM_UNDELEGATED > RMI_OP_MEM_CONDITIONAL Ack > > Currently, the check confirming the state is RMI_OP_MEM_DELEGATED occurs > relatively late in the function execution. It seems this function is > explicitly designed to handle only RMI_OP_MEM_DELEGATED. No, that is not correct. The function handles both OP_MEM_DELEGATED and OP_MEM_UNDELEGATED. In the former case, we explicitly "delegate" the pages before donating. The "UNDELEGATED" case doesn't need to do that extra step. > > Given that this is an exported interface, would it make sense to > fail-fast by moving this validation to the very beginning of the function? > Even if RMI_OP_MEM_CONDITIONAL is intended for future use, it should Yep, agree. We can rejec the CONDITIONAL ones. > probably be rejected as invalid for now. Also, it is not clear why the > current check is inside the loop while the state itself doesn't get > modified. As above, that check is additionally preparing the memory for RMM consumption. > > If this is a valid concern, the same architectural pattern should likely be > applied to rmi_sro_donate_contig(). > Ack, we can reject the CONDITIONAL ones. Suzuki