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 BDB7C13BAE5; Wed, 17 Apr 2024 10:19:47 +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=1713349189; cv=none; b=e8BHqSomPqrmFk9Rmo48I787jKX/fNrsPWvxQN6V9Y7kq0z1RCu+IbRuQ8vWKdRXzFAVe5enZjM8r4UooDVZEW41ugnudCQFfH0SUcWujEdevbEfTaa58MH0LOPgTxYs0/sCZA6ahOHg74QMMd4Ibl6OByxANd6qqDVeAm6YPgk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713349189; c=relaxed/simple; bh=KpH/GhjCXXgVAzGKKcfwNjiWuVqRoJLtjOgyw/WOkf4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FQ43uaDRNiYx/418go/BoNLHHimBIKjaOz7TPdEebcdloW4NgHTZc/sqWhmDekLQAXH0+3tMgKX22AZgztGo3UdJ/fK+8ETaDxiuJMG7g9rhMeSDmHnuXggR4ig9E36XNkxSolLlS0pzxowp0JN25knLkAiCfpInoX+yzqUqHfo= 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; 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 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 0D734339; Wed, 17 Apr 2024 03:20:15 -0700 (PDT) Received: from [10.1.39.28] (FVFF763DQ05P.cambridge.arm.com [10.1.39.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BCD063F64C; Wed, 17 Apr 2024 03:19:44 -0700 (PDT) Message-ID: Date: Wed, 17 Apr 2024 11:19:42 +0100 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 12/43] arm64: RME: Keep a spare page delegated to the RMM Content-Language: en-GB To: Steven Price , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Catalin Marinas , Marc Zyngier , Will Deacon , James Morse , Oliver Upton , 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 References: <20240412084056.1733704-1-steven.price@arm.com> <20240412084309.1733783-1-steven.price@arm.com> <20240412084309.1733783-13-steven.price@arm.com> From: Suzuki K Poulose In-Reply-To: <20240412084309.1733783-13-steven.price@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Steven On 12/04/2024 09:42, Steven Price wrote: > Pages can only be populated/destroyed on the RMM at the 4KB granule, > this requires creating the full depth of RTTs. However if the pages are > going to be combined into a 4MB huge page the last RTT is only minor nit: 2MB huge page. > temporarily needed. Similarly when freeing memory the huge page must be > temporarily split requiring temporary usage of the full depth oF RTTs. > > To avoid needing to perform a temporary allocation and delegation of a > page for this purpose we keep a spare delegated page around. In > particular this avoids the need for memory allocation while destroying > the realm guest. > > Signed-off-by: Steven Price > --- > arch/arm64/include/asm/kvm_rme.h | 5 +++++ > arch/arm64/kvm/rme.c | 8 ++++++++ > 2 files changed, 13 insertions(+) > > diff --git a/arch/arm64/include/asm/kvm_rme.h b/arch/arm64/include/asm/kvm_rme.h > index cf8cc4d30364..fba85e9ce3ae 100644 > --- a/arch/arm64/include/asm/kvm_rme.h > +++ b/arch/arm64/include/asm/kvm_rme.h > @@ -50,6 +50,9 @@ enum realm_state { > * @state: The lifetime state machine for the realm > * @rd: Kernel mapping of the Realm Descriptor (RD) > * @params: Parameters for the RMI_REALM_CREATE command > + * @spare_page: A physical page that has been delegated to the Realm world but > + * is otherwise free. Used to avoid temporary allocation during > + * RTT operations. > * @num_aux: The number of auxiliary pages required by the RMM > * @vmid: VMID to be used by the RMM for the realm > * @ia_bits: Number of valid Input Address bits in the IPA > @@ -60,6 +63,8 @@ struct realm { > void *rd; > struct realm_params *params; > > + phys_addr_t spare_page; > + > unsigned long num_aux; > unsigned int vmid; > unsigned int ia_bits; > diff --git a/arch/arm64/kvm/rme.c b/arch/arm64/kvm/rme.c > index 658d14e8d87d..9652ec6ab2fd 100644 > --- a/arch/arm64/kvm/rme.c > +++ b/arch/arm64/kvm/rme.c > @@ -103,6 +103,7 @@ static int realm_create_rd(struct kvm *kvm) > } > > realm->rd = rd; > + realm->spare_page = PHYS_ADDR_MAX; > > if (WARN_ON(rmi_rec_aux_count(rd_phys, &realm->num_aux))) { > WARN_ON(rmi_realm_destroy(rd_phys)); > @@ -283,6 +284,13 @@ void kvm_destroy_realm(struct kvm *kvm) > > rme_vmid_release(realm->vmid); > > + if (realm->spare_page != PHYS_ADDR_MAX) { > + /* Leak the page if the undelegate fails */ > + if (!WARN_ON(rmi_granule_undelegate(realm->spare_page))) > + free_page((unsigned long)phys_to_virt(realm->spare_page)); > + realm->spare_page = PHYS_ADDR_MAX; > + } > + > for (i = 0; i < pgt->pgd_pages; i++) { > phys_addr_t pgd_phys = kvm->arch.mmu.pgd_phys + i * PAGE_SIZE; > Reviewed-by: Suzuki K Poulose