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 7A0EA39C65E; Tue, 28 Apr 2026 23:25:18 +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=1777418718; cv=none; b=Et0m3sR6+bJQZb4IK58dEpchrc4t+Fr6Z4/rpd1y2TgjGE5REwmBNy0QIkCVPW9uCgOzezRV2FsRJM4OEpk64+RgKTqVXgsai7vCyalZHCBk2gvPyIJqQUHMZs50w0flbUdlgOZ5koyynUud2YaaRRoXV4pkA5/6isqk1JmzwPU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777418718; c=relaxed/simple; bh=hBmKFJnOCs0S5g+APYD+DID3z1acALZDNcnsp4e/ipc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=ZvBD1qcg/O+BOnHQVtOVy5vJDFiPfstJiiVAMrQmqJY8fHSa4KvqVRHD1cArGQNP5yUNSZEIOmz0VBTlocfTeYsGpXyby69HBdG2sBFYJMLYoUTp4LYn4A6Au93LVSup5BmS+z+fzjTTeXoUW2DBAHImI6Sl2D8MKQwGpV++K7E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=g9sRFF7e; 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="g9sRFF7e" Received: by smtp.kernel.org (Postfix) with ESMTPS id 41061C2BCB8; Tue, 28 Apr 2026 23:25:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777418718; bh=hBmKFJnOCs0S5g+APYD+DID3z1acALZDNcnsp4e/ipc=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=g9sRFF7el4fEV5s0maeinfAKTleEfhhp6J904O234x5NF5cP7/mqyGqI1TL3At/cF vc5C0L/C1SObDX9GIcocqJ4y2b9TDFB2yNaVHb2Li98zHzuFPsZOzPLgv2loINQBrG 0fSPZbjBQuQtdG3v6RvTjv4lswKBlby+7Lee9R2FmEotsWpMy9bTpmg34g3JLjEbnP Btu10P464zJ77Y8OpywMRHg+q5yVHUd+X5wRgfeIcmwExg4K7+gjjni2+OTWrc0xmH mTivun07fYtU4dpcmuhiOuQJWqvKXM4+rix+MYgK18rEdjSUrpBoUd4VCQm3N77IEY bCjmjOsrMCaqQ== 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 2391FFF887E; Tue, 28 Apr 2026 23:25:18 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Tue, 28 Apr 2026 16:25:08 -0700 Subject: [PATCH RFC v5 13/53] KVM: guest_memfd: Return early if range already has requested attributes Precedence: bulk X-Mailing-List: linux-trace-kernel@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: <20260428-gmem-inplace-conversion-v5-13-d8608ccfca22@google.com> References: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@google.com> In-Reply-To: <20260428-gmem-inplace-conversion-v5-0-d8608ccfca22@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, ira.weiny@intel.com, 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, 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 , Baoquan He , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Jason Gunthorpe , Vlastimil Babka 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=1777418714; l=2437; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=2jwl4vZPlGQvOmnwH/oYNhanxNv5t/UdBGux+AjU5aQ=; b=1XrRoXlZ6YyE/8zRKL/CERwfqop5gZw5Z1bMhGmpG5iD5nCUiQ9BfUkM3SKtE7wFQPAeWBH9t qnBc56ZHLjWD+SmyF3p6GdHGVRlIhFa7pRDpwx9wFvKpRHafBXps6VW 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. Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 33 ++++++++++++++++++++++++--------- 1 file changed, 24 insertions(+), 9 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index d563d80d4accb..d8bdb51c50cf0 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -92,6 +92,23 @@ 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 maple_tree *mt, + pgoff_t index, size_t nr_pages, + u64 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 (xa_to_value(entry) != attributes) + return false; + } + + return true; +} + static int __kvm_gmem_prepare_folio(struct kvm *kvm, struct kvm_memory_slot *slot, pgoff_t index, struct folio *folio) { @@ -667,6 +684,11 @@ static int __kvm_gmem_set_attributes(struct inode *inode, pgoff_t start, filemap_invalidate_lock(mapping); + if (kvm_gmem_range_has_attributes(mt, start, nr_pages, attrs)) { + r = 0; + goto out; + } + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { @@ -1152,20 +1174,13 @@ EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn); static bool kvm_gmem_range_is_private(struct gmem_inode *gi, pgoff_t index, size_t nr_pages, struct kvm *kvm, gfn_t gfn) { - pgoff_t end = index + nr_pages - 1; - void *entry; - if (vm_memory_attributes) return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, KVM_MEMORY_ATTRIBUTE_PRIVATE, KVM_MEMORY_ATTRIBUTE_PRIVATE); - mt_for_each(&gi->attributes, entry, index, end) { - if (xa_to_value(entry) != KVM_MEMORY_ATTRIBUTE_PRIVATE) - return false; - } - - return true; + return kvm_gmem_range_has_attributes(&gi->attributes, index, nr_pages, + KVM_MEMORY_ATTRIBUTE_PRIVATE); } static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.54.0.545.g6539524ca2-goog