From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.14]) (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 32B033A3E67; Tue, 23 Jun 2026 05:25:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782192342; cv=none; b=u1qfz/l3vPJg7RfmEtWx0oY54OHeG6RkCWytsFjpXKeqJnMk3tozRdSKFn6v2nPJ7gECiYcK/JQk9vaQ8oOF5Kza2dhT8coqJ2zpJORyY9v7TCEBrEjp+H7ATpTI8nLEH8CPCTCKdbmb4+01qZJHN51Ts6xgGCg3kwgk30LACs8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782192342; c=relaxed/simple; bh=Uq5PeCcyAK+bL5pMg1ybj6yxp4BAEe7DhiVVYVptiko=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=rf5b3U1Dt5a4zL+eAtBVGEVlO42NDEwLQwMz+Au/K7CZrHPS1GUZVy2w9+CpepKdGf+C4s0tY2yBSw2eglZ6RmksCU2u/MHyNgPnD/8CzVlXjb6atkbuodTNxtFlJXwAogBMxG3Oq8zfNcpPPdIqTdGYEWUu8GDup7vx93EvNww= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=BgvzCYVT; arc=none smtp.client-ip=198.175.65.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="BgvzCYVT" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782192341; x=1813728341; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=Uq5PeCcyAK+bL5pMg1ybj6yxp4BAEe7DhiVVYVptiko=; b=BgvzCYVT7WekwkghBtpcD1qh2JYOV8asN7CSeE4a0wEjhWbnjOQSZejL dtYHLbQvujqFcyXFqqLJLK/sEk4b8mYRH7x48vvadqeBxTuAhI14vBYBs bqOdUKXjF1DzbStpCPw0f6KxGdaBDnvIB+YYQLJ6xumGDcQaAgZX172fj 8egJBTf4c8Xx0ycpbqOJzQIMEZEgzazZRfptbfZ4D+09MHa30zAMQ7LrQ j7JK7Kse6NYefL+Xe5oEPq4z9S0riyVLJLkNbOwa2DwWVP/aOXgEYdeto JRUtManq0SXxpIXz3q2vePFR6EuQ881u1m75dFdkoi068A/rTaoS0kU/u A==; X-CSE-ConnectionGUID: uNk5dytXQHiYMnaEYhhnzw== X-CSE-MsgGUID: J3dTFPg3RT+es+zT7QTH/Q== X-IronPort-AV: E=McAfee;i="6800,10657,11825"; a="86834044" X-IronPort-AV: E=Sophos;i="6.24,220,1774335600"; d="scan'208";a="86834044" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2026 22:25:40 -0700 X-CSE-ConnectionGUID: +QKs7F9+Ru2ErBNCyvGNzg== X-CSE-MsgGUID: MlbtBeXQTPSGpda7Y/yfxQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,220,1774335600"; d="scan'208";a="245058541" Received: from unknown (HELO [10.238.2.81]) ([10.238.2.81]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 22 Jun 2026 22:25:26 -0700 Message-ID: <1b59fec2-a464-4429-8532-880394912af5@linux.intel.com> Date: Tue, 23 Jun 2026 13:25:24 +0800 Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 09/46] KVM: guest_memfd: Introduce function to check GFN private/shared status To: ackerleytng@google.com Cc: aik@amd.com, andrew.jones@linux.dev, 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 , 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 References: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> <20260618-gmem-inplace-conversion-v8-9-9d2959357853@google.com> Content-Language: en-US From: Binbin Wu In-Reply-To: <20260618-gmem-inplace-conversion-v8-9-9d2959357853@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/19/2026 8:31 AM, Ackerley Tng via B4 Relay wrote: > From: Ackerley Tng > > Introduce function for KVM to check the private/shared status of guest ^ Nit: a > memory at a given GFN. > > This will be used in a later patch. [...] > > +bool kvm_gmem_is_private(struct kvm *kvm, gfn_t gfn) > +{ > + struct kvm_memory_slot *slot = gfn_to_memslot(kvm, gfn); > + struct inode *inode; > + > + /* > + * If this gfn has no associated memslot, there's no chance of the gfn > + * being backed by private memory, since guest_memfd must be used for > + * private memory, "guest_memfd must be used for private memory" is a bit confusing to me. > and guest_memfd must be associated with some memslot. > + */ > + if (!slot) > + return 0; > + > + CLASS(gmem_get_file, file)(slot); > + if (!file) > + return 0; > + > + inode = file_inode(file); > + > + /* > + * Rely on the maple tree's internal RCU lock to ensure a > + * stable result. This result can become stale as soon as the > + * lock is dropped, so the caller _must_ still protect > + * consumption of private vs. shared by checking > + * mmu_invalidate_retry_gfn() under mmu_lock to serialize > + * against ongoing attribute updates. > + */ > + return kvm_gmem_is_private_mem(inode, kvm_gmem_get_index(slot, gfn)); > +} > +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_is_private); > + > static struct file_operations kvm_gmem_fops = { > .mmap = kvm_gmem_mmap, > .open = generic_file_open, >