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 01E1B1CFEDC; Wed, 23 Oct 2024 14:35:42 +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=1729694145; cv=none; b=Tkr1nEm2QM4Do9jPv93ntXPKJaC2UGYSPsoC9wPOqz4RGhBUJxHtFWAkxb/zPA8KxRCMkQc7+Qv84jFl9epN/2pUfq01U5cCoWkuh8A5d0uZBB9X8FJ6k/Xq3o4ehQca0EihcenxXczpOCDsrkWgSq/5rCpyaDzNf6tlN4Gbm6A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729694145; c=relaxed/simple; bh=l68G4xs/wglFkcKCnUp2kdZ0MOFIFNVe7VqWRN/gcjE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ZFTStzpOEpBDOPc3PCHkOBQyyz3HhzqjfWnZNBWhlvnYdDQu3t1C6v5FEUdrxsbeZe87SE3BV4iWzVu/ubggOluhGj7pd3oONfcl57kEVoptrrKa0dkt2TzGVUSwBRw3KIX9xOrqpUtAAG220ulvfgnV6lvt/rIEtpHpk0mYIN8= 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 E145E339; Wed, 23 Oct 2024 07:36:11 -0700 (PDT) Received: from [10.57.23.17] (unknown [10.57.23.17]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 045763F71E; Wed, 23 Oct 2024 07:35:37 -0700 (PDT) Message-ID: <7d02ed25-7618-4920-8f35-9e480cdf709f@arm.com> Date: Wed, 23 Oct 2024 15:35:35 +0100 Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 02/43] kvm: arm64: pgtable: Track the number of pages in the entry level To: Gavin Shan , kvm@vger.kernel.org, kvmarm@lists.linux.dev Cc: Suzuki K Poulose , 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 , Shanker Donthineni , Alper Gun , "Aneesh Kumar K . V" References: <20241004152804.72508-1-steven.price@arm.com> <20241004152804.72508-3-steven.price@arm.com> <032d29e7-b6a3-4493-833b-a9b6d9496a75@redhat.com> From: Steven Price Content-Language: en-GB In-Reply-To: <032d29e7-b6a3-4493-833b-a9b6d9496a75@redhat.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 23/10/2024 05:03, Gavin Shan wrote: > On 10/5/24 1:27 AM, Steven Price wrote: >> From: Suzuki K Poulose >> >> Keep track of the number of pages allocated for the top level PGD, >> rather than computing it every time (though we need it only twice now). >> This will be used later by Arm CCA KVM changes. >> >> Signed-off-by: Suzuki K Poulose >> Signed-off-by: Steven Price >> --- >>   arch/arm64/include/asm/kvm_pgtable.h | 2 ++ >>   arch/arm64/kvm/hyp/pgtable.c         | 5 +++-- >>   2 files changed, 5 insertions(+), 2 deletions(-) >> > > If we really want to have the number of pages for the top level PGDs, > the existing helpers kvm_pgtable_stage2_pgd_size() for the same purpose > needs to replaced by (struct kvm_pgtable::pgd_pages << PAGE_SHIFT) and > then removed. > > The alternative would be just to use kvm_pgtable_stage2_pgd_size() > instead of > introducing struct kvm_pgtable::pgd_pages, which will be used in the slow > paths where realm is created or destroyed. I think just dropping this patch and using kvm_pgtable_stage2_pgd_size() in the slow paths makes sense. I think originally there had been some issue with the value being hard to obtain in the relevant path, but I can't see any problem now. Thanks, Steve >> diff --git a/arch/arm64/include/asm/kvm_pgtable.h >> b/arch/arm64/include/asm/kvm_pgtable.h >> index 03f4c3d7839c..25b512756200 100644 >> --- a/arch/arm64/include/asm/kvm_pgtable.h >> +++ b/arch/arm64/include/asm/kvm_pgtable.h >> @@ -404,6 +404,7 @@ static inline bool kvm_pgtable_walk_lock_held(void) >>    * struct kvm_pgtable - KVM page-table. >>    * @ia_bits:        Maximum input address size, in bits. >>    * @start_level:    Level at which the page-table walk starts. >> + * @pgd_pages:        Number of pages in the entry level of the >> page-table. >>    * @pgd:        Pointer to the first top-level entry of the page-table. >>    * @mm_ops:        Memory management callbacks. >>    * @mmu:        Stage-2 KVM MMU struct. Unused for stage-1 page-tables. >> @@ -414,6 +415,7 @@ static inline bool kvm_pgtable_walk_lock_held(void) >>   struct kvm_pgtable { >>       u32                    ia_bits; >>       s8                    start_level; >> +    u8                    pgd_pages; >>       kvm_pteref_t                pgd; >>       struct kvm_pgtable_mm_ops        *mm_ops; >>   diff --git a/arch/arm64/kvm/hyp/pgtable.c >> b/arch/arm64/kvm/hyp/pgtable.c >> index b11bcebac908..9e1be28c3dc9 100644 >> --- a/arch/arm64/kvm/hyp/pgtable.c >> +++ b/arch/arm64/kvm/hyp/pgtable.c >> @@ -1534,7 +1534,8 @@ int __kvm_pgtable_stage2_init(struct kvm_pgtable >> *pgt, struct kvm_s2_mmu *mmu, >>       u32 sl0 = FIELD_GET(VTCR_EL2_SL0_MASK, vtcr); >>       s8 start_level = VTCR_EL2_TGRAN_SL0_BASE - sl0; >>   -    pgd_sz = kvm_pgd_pages(ia_bits, start_level) * PAGE_SIZE; >> +    pgt->pgd_pages = kvm_pgd_pages(ia_bits, start_level); >> +    pgd_sz = pgt->pgd_pages * PAGE_SIZE; >>       pgt->pgd = (kvm_pteref_t)mm_ops->zalloc_pages_exact(pgd_sz); >>       if (!pgt->pgd) >>           return -ENOMEM; >> @@ -1586,7 +1587,7 @@ void kvm_pgtable_stage2_destroy(struct >> kvm_pgtable *pgt) >>       }; >>         WARN_ON(kvm_pgtable_walk(pgt, 0, BIT(pgt->ia_bits), &walker)); >> -    pgd_sz = kvm_pgd_pages(pgt->ia_bits, pgt->start_level) * PAGE_SIZE; >> +    pgd_sz = pgt->pgd_pages * PAGE_SIZE; >>       pgt->mm_ops->free_pages_exact(kvm_dereference_pteref(&walker, >> pgt->pgd), pgd_sz); >>       pgt->pgd = NULL; >>   } > > Thanks, > Gavin >