From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3962E29DB6C; Wed, 29 Jul 2026 00:35:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785285309; cv=none; b=AzteWNobtL75h+4RVchrkUQUMJnfmCWyuErHPLkwOOKz/Sm76FvkM1Ai2tqgrmke6pEbXMcYtcHHKyadT37Q9aNLgV0jxLkcOod0THWGL5pUBSaFxLfTxWNtT4YSU7b3X5X17ySpRC3eP/40P+RrugvzDmmWdcfzAB2Mjrtakow= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785285309; c=relaxed/simple; bh=VQp8VV/1HjrBbDW4b7xKHc9A6fUmeLHK+Zex8LeUIVk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=GsGtJxX5rWEuT37iEhvmpk3WhScEPMxUnsbKJ+2/N6cyPXkJD/InRZbPatSb4ivl9gT1JmO7hoC1/dx/9IHH3r9icwdBYwOPgnHlgILmL5mf51PYWzr6KwjiOjjGlTScuTgvemRDMPN/5bt7cGok5rDs40Ta17QEuCm5j5v1uKo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HJTKylt0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HJTKylt0" Received: by smtp.kernel.org (Postfix) with ESMTPS id D8C06C4AF68; Wed, 29 Jul 2026 00:35:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1785285308; bh=VQp8VV/1HjrBbDW4b7xKHc9A6fUmeLHK+Zex8LeUIVk=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=HJTKylt03lwuH5+7v5RVmlBfup7e1wj6WuZd61cQatjmZHCmlQswUjFvbTmTaFKDT NZfU3BfZnpUJoxjjagTKC8fmeRg23af3mTtmZn0awfXqeuxVaQgCZqOJrgZrnB0iXT GU1TkIfXmt52Cv1I52hZYGGwjl5tTRWk5GfJPMgwZAkqS8PAPpuQ7HIRzmKS3t5n4R HSwj7ogqTFjzhwTioF1xuscBdh2vW2ePa1eA7Ieezkrssk88GfQDKvDEchBH41yad9 qK6Q5RMqj35UgHxZ76rC2WVrPEYBlYbAYhQYkm6t9U5o7X1O+/VmL7Ybti6h7gqdz/ yAdR/tXxnD9VQ== Received: from aws-us-west-2-korg-lkml-1.web.codeaurora.org (localhost.localdomain [127.0.0.1]) by smtp.lore.kernel.org (Postfix) with ESMTP id C0D15C54F5C; Wed, 29 Jul 2026 00:35:08 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Tue, 28 Jul 2026 17:35:12 -0700 Subject: [PATCH v9 13/41] KVM: guest_memfd: Return early if range already has requested attributes Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260728-gmem-inplace-conversion-v9-13-35f9aec2aed2@google.com> References: <20260728-gmem-inplace-conversion-v9-0-35f9aec2aed2@google.com> In-Reply-To: <20260728-gmem-inplace-conversion-v9-0-35f9aec2aed2@google.com> To: aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, david@kernel.org, jmattson@google.com, jthoughton@google.com, michael.roth@amd.com, oupton@kernel.org, pankaj.gupta@amd.com, qperret@google.com, rick.p.edgecombe@intel.com, rientjes@google.com, shivankg@amd.com, steven.price@arm.com, tabba@google.com, willy@infradead.org, wyihan@google.com, yan.y.zhao@intel.com, forkloop@google.com, pratyush@kernel.org, suzuki.poulose@arm.com, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , Jason Gunthorpe , Vlastimil Babka , Baoquan He Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, Ackerley Tng X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1785285305; l=2782; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=VCw8XceJPrjTLah5c+6aK9kQo6IEla8VXHadDNB1FcI=; b=dcBMZOr0ZBpW+kNZxueejs5pg+E2UIMJT+1ewBhICvI6Vm083tE0K24FdLuoGexaDLE8ccRD+ CED+onKhmkZCsGNLk6P9uXKblDRgo65C2kzAuAT5L5xLYT5Ht370hxA X-Developer-Key: i=ackerleytng@google.com; a=ed25519; pk=sAZDYXdm6Iz8FHitpHeFlCMXwabodTm7p8/3/8xUxuU= X-Endpoint-Received: by B4 Relay for ackerleytng@google.com/20260225 with auth_id=649 X-Original-From: Ackerley Tng Reply-To: ackerleytng@google.com From: Ackerley Tng Extract a helper out of kvm_gmem_range_is_private() that checks that a range has given attributes. Optimize setting memory attributes by returning early if all pages in the requested range already has the requested attributes. Reviewed-by: Fuad Tabba Tested-by: Shivank Garg Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 35 ++++++++++++++++++++++++----------- 1 file changed, 24 insertions(+), 11 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 612fcde4ae8ea..928fc7f4a01e4 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -94,6 +94,24 @@ static bool kvm_gmem_is_shared_mem(struct inode *inode, pgoff_t index) return !kvm_gmem_is_private_mem(inode, index); } +static bool kvm_gmem_range_has_attributes(struct inode *inode, + pgoff_t index, size_t nr_pages, + u64 attributes) +{ + struct maple_tree *mt = &GMEM_I(inode)->attributes; + pgoff_t end = index + nr_pages - 1; + void *entry; + + lockdep_assert(mt_lock_is_held(mt)); + + mt_for_each(mt, entry, index, end) { + if (kvm_gmem_interpret_entry(inode, entry) != attributes) + return false; + } + + return true; +} + /* * Returns a locked folio on success. The caller is responsible for * setting the up-to-date flag before the memory is mapped into the guest. @@ -611,12 +629,15 @@ static int __kvm_gmem_set_attributes(struct inode *inode, pgoff_t start, pgoff_t end = start + nr_pages; struct maple_tree *mt; struct ma_state mas; - int r; + int r = 0; mt = &gi->attributes; filemap_invalidate_lock(mapping); + if (kvm_gmem_range_has_attributes(inode, start, nr_pages, attrs)) + goto out; + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { @@ -1107,22 +1128,14 @@ static bool kvm_range_is_private(struct file *file, pgoff_t index, size_t nr_pages, struct kvm *kvm, gfn_t gfn) { struct inode *inode = file_inode(file); - pgoff_t last = index + nr_pages - 1; - struct maple_tree *mt; - void *entry; if (!gmem_in_place_conversion) return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE, KVM_MEMORY_ATTRIBUTE_PRIVATE); - mt = &GMEM_I(inode)->attributes; - mt_for_each(mt, entry, index, last) { - if (kvm_gmem_interpret_entry(inode, entry) != - KVM_MEMORY_ATTRIBUTE_PRIVATE) - return false; - } - return true; + return kvm_gmem_range_has_attributes(inode, index, nr_pages, + KVM_MEMORY_ATTRIBUTE_PRIVATE); } static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.55.0.508.g3f0d502094-goog