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 7382723BCEE; Fri, 19 Jun 2026 00:31:48 +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=1781829108; cv=none; b=bqpgDdZH0lHVZN+nOutRFVzlZ1/IbMFqKhDY1RoUz51fp5qyI/n8f9NYDXpANULDm5Aci8fMyn9C7F2IcCgNpUmUjJzTZZiSq/15YaT9nkg9FEFKTE0Onm63/+MwgDOeQut9F7ugdTOJEIBCMOfGZVFgcBYN+g07tQSVuK4b15U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781829108; c=relaxed/simple; bh=77tno+1BEzOBJ5VyiPmvluDUJLKSOaYf+ccqqrV2opE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=XU6+GJJg6Z0fcGTTxPV1W9FeTAIlruATnTbpXRuriosXsVHZUlIy1g13nGmSKwcjhYtuh2BKGnQdmYGj4ELsUCfa3QC8kYJUa+bjebc4TjOi8u5ncMmGZ0io0BWSwFHLcausuje1+88m5BlXdhrUUI5ge9YiBp2GEFMYDo5xb4U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jiXcLSdQ; 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="jiXcLSdQ" Received: by smtp.kernel.org (Postfix) with ESMTPS id 4FFFEC4AF63; Fri, 19 Jun 2026 00:31:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1781829108; bh=77tno+1BEzOBJ5VyiPmvluDUJLKSOaYf+ccqqrV2opE=; h=From:Date:Subject:References:In-Reply-To:To:Cc:Reply-To:From; b=jiXcLSdQVJ5yO4ecfWTvDsnDGky5JHVZcLf3y5slRlbHhD2/VGTRFoT8hPXhodcwM fYPLFIF72Y6W7m37/DQiD4xR+Kj/VIGnp08F9Awxk+oN/T7WS6irTQv84K4Ngn9y7L DZp0aDz1fBzQ8Xi2phYIhUN6YzuGfFvcj5j8eO8znmoJcAR6FGMM6FQ9ALCKnoQfe1 y3oUws0G8Smc5A9hX3iFwhbl+fspjJRmoOgkFzfzeQdfZ58ks/K9Y283WILEJtmIjs VzbcYzy0+EZ9/5k6IrepB+w1FbZtebPMMfbaiBe/xJ3Fx2zpnKofg6WPX8QnLNk2ec zJ+mOk3sk3gcg== 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 410CDCD98FA; Fri, 19 Jun 2026 00:31:48 +0000 (UTC) From: Ackerley Tng via B4 Relay Date: Thu, 18 Jun 2026 17:31:53 -0700 Subject: [PATCH v8 16/46] KVM: guest_memfd: Return early if range already has requested attributes Precedence: bulk X-Mailing-List: linux-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: <20260618-gmem-inplace-conversion-v8-16-9d2959357853@google.com> References: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> In-Reply-To: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@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 , 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=1781829104; l=2581; i=ackerleytng@google.com; s=20260225; h=from:subject:message-id; bh=XtB3xaNYZoGgLjv/gUxy02ochDW78D95+vPEFAYFilQ=; b=8DN2flcUdZvH8IsUjtTwKQwrPHe3JRoPhgMeWB3OXFnqBo/oCJQj5p5x5PXtVI47Jk7xP3NoS AvdvXpAVzJeBJFJ3PPfPlZOPbVNtUoRPW7WV6NpG4Zt7fl73nxNK7BC 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 Signed-off-by: Ackerley Tng --- virt/kvm/guest_memfd.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 3c94442bc8131..cec8fa26ece17 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -86,6 +86,23 @@ 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) { @@ -653,12 +670,15 @@ 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(mt, start, nr_pages, attrs)) + goto out; + mas_init(&mas, mt, start); r = kvm_gmem_mas_preallocate(&mas, attrs, start, nr_pages); if (r) { @@ -1148,19 +1168,14 @@ static bool kvm_gmem_range_is_private(struct file *file, pgoff_t index, size_t nr_pages, struct kvm *kvm, gfn_t gfn) { struct maple_tree *mt = &GMEM_I(file_inode(file))->attributes; - pgoff_t end = index + nr_pages - 1; - 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_for_each(mt, entry, index, end) { - if (xa_to_value(entry) != KVM_MEMORY_ATTRIBUTE_PRIVATE) - return false; - } - return true; + return kvm_gmem_range_has_attributes(mt, index, nr_pages, + KVM_MEMORY_ATTRIBUTE_PRIVATE); } static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, -- 2.55.0.rc0.738.g0c8ab3ebcc-goog