From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.13]) (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 630B53F0765; Tue, 30 Jun 2026 12:19:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.13 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782821985; cv=none; b=idRnb0hbETsmokcU1Y/YiKnp7inS78YQbmrZUNBM/uuwTOUCT+f6xYIC8SIHnXk1Rx6ZQyrfDS8s4SXrNxgVmsZZNkWQU1VKP+PPZvWKKztSBS8yv7YzV032KqZf/G4IEcCExZwZIs+/+/PCCIbfrrQEwcPPQd1ABvkuEYRu/bE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782821985; c=relaxed/simple; bh=eazOhytQrFMvUq1ReP67qLKPgCSBV6aajIEIlT27i24=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=Y2DTPpnn4xof2jwePa5r0PuOg7ZXk3X1+I7CciAc5p8Ge1s9h+yx3zpFF8+hWZ4pVCkO0CeG8ONl1nLh/FmoPokMwnZcxG6R0nH5N7YpIhyNBpo3XGJRJoiu6wJ0qiwGIIsew/szDipYu+GvhiQbdJxAnvxp55D6QbhEOFipS7A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=FGJaBBIF; arc=none smtp.client-ip=198.175.65.13 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="FGJaBBIF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1782821984; x=1814357984; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=eazOhytQrFMvUq1ReP67qLKPgCSBV6aajIEIlT27i24=; b=FGJaBBIFz6yvBo2f2TDAFh0t9d7AI//1zWaI3NCu6PKQLGp3tAP6Id8G +KV99JMcVrm+DAzVSDMMHDfzFRi5EQ3QHqZmXoGo4lcAAbFTwWsKdjK8e 1HpP45qFSO2o7kz5Xgd3r4+AZaiV/dmA7XFZamR6ZhNM55Xx0VVPlxAFb Dj3MFQqx6GWO0qG/blCOb8m3GXrYtmqOUDtMjuA3FjPR6KSXUcydXNV/r 6WokWulxqzoDW/eM/upNg4+BwqMxan8CK4dnxMoVFOPIp10ObdBpfFudd d/N2513uEySoDvsj7XIxicTJiqA2r2jT7yD+PmIMWDX8blSN8dSXoc3G6 w==; X-CSE-ConnectionGUID: caNl5UQ1SRuRB/eovcqpvg== X-CSE-MsgGUID: a3FKF91CS0GeysoFxyXfoA== X-IronPort-AV: E=McAfee;i="6800,10657,11832"; a="94683316" X-IronPort-AV: E=Sophos;i="6.24,233,1774335600"; d="scan'208";a="94683316" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jun 2026 05:19:44 -0700 X-CSE-ConnectionGUID: B7OjnqsRQEixcvKJEwnbxg== X-CSE-MsgGUID: dfLIyfHYTAKDobdyePXMlQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.24,233,1774335600"; d="scan'208";a="254160487" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.239.158.70]) ([10.239.158.70]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Jun 2026 05:19:30 -0700 Message-ID: Date: Tue, 30 Jun 2026 20:19:27 +0800 Precedence: bulk X-Mailing-List: linux-trace-kernel@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, 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 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 References: <20260618-gmem-inplace-conversion-v8-0-9d2959357853@google.com> <20260618-gmem-inplace-conversion-v8-9-9d2959357853@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20260618-gmem-inplace-conversion-v8-9-9d2959357853@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed 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 > memory at a given GFN. > > This will be used in a later patch. > > Signed-off-by: Ackerley Tng > Co-developed-by: Sean Christopherson > Signed-off-by: Sean Christopherson With binbin's comment resolved, Reviewed-by: Xiaoyao Li BTW, it looks better to move the patch 01 just behind this one. > --- > include/linux/kvm_host.h | 2 ++ > virt/kvm/guest_memfd.c | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 33 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index 3915da2a61778..27687fb9d5201 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -2575,6 +2575,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) > #endif /* CONFIG_KVM_VM_MEMORY_ATTRIBUTES */ > > #ifdef CONFIG_KVM_GUEST_MEMFD > +bool kvm_gmem_is_private(struct kvm *kvm, gfn_t gfn); > + > int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, > gfn_t gfn, kvm_pfn_t *pfn, struct page **page, > int *max_order); > diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c > index 8101f64e0366f..bca912db5be6e 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -510,6 +510,37 @@ static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma) > return 0; > } > > +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, 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, >