From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f197.google.com (mail-pg1-f197.google.com [209.85.215.197]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CE923B71A5 for ; Tue, 25 Aug 2026 18:55:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787684162; cv=none; b=YitZJka4p6HRdZXjNskTtvbiHxROesCrALNvbH7NepJwPLhmClJKsmtvZ1UGqn0kDKSUcaHXDRd7z157a8apNLUDfpu8d4DOU18JRfoXGV84Em6f9k86bK+tyEN9A5UCMtnQGwBaeof+KThib90EreRPqUsYmNpTZRJ7Xu9Xg5s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787684162; c=relaxed/simple; bh=v81i0R08OhPbKwodLqy3PT8ECRERns8YsJia2mMgPmU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Mr+FNlYb8qbAYgnXrWYUWbmeLLQ0Ukcmjfz+le+6eYNdT/IqFSdrzaxxhiHDfSsmDP4af+nXmFAW28kQ8KMVYgQf+9+iZ4AE5/Qot6bUFkJEr7i30vLWT+bBzdf1aQdAvZi8Jq0m9sbO9MnzRlQHNB0FjG7Nn5IofJLmo4KQNGc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=sGgIdWUb; arc=none smtp.client-ip=209.85.215.197 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="sGgIdWUb" Received: by mail-pg1-f197.google.com with SMTP id 41be03b00d2f7-ca124bf0189so1167374a12.0 for ; Tue, 25 Aug 2026 11:55:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1787684155; x=1788288955; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=xccKXo6SW1SbkIzehhqjd8J3GgWcAs1E82/+Xs14ta0=; b=sGgIdWUb73c/AqT0Od7PZttUhmzl/K1z+Trk9csyZZTKUuB9AJnfgvEciFEwGi2GSz r40w0dHoz+sUI0NWkw1RQXLydLHvEi7GAXsiSumQgC5I0EoON9A8hxXKHMuejhs/0Abq RVGBMjwVtxoy+hrGodz7hw+PoWJSzgw0HTjuZfU8jz1igt09Fegq5v72EnhUTCytzoiB xiuwfnRG+RNbYiqfTr6temxrgoUkWNxzshhGu4S2eqU0qg7v0V6FjenYa8nlyBbdcuw3 DDlrTqsQefJ+ZzvwXKAFV1vwcQ2NdPqnl/BXZmxYJ0sj9t8c2ygKLxORrssa4VVA8e18 3xYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787684155; x=1788288955; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=xccKXo6SW1SbkIzehhqjd8J3GgWcAs1E82/+Xs14ta0=; b=IogGkVlouUbwvWZfC2f37oY7sod7VDGI3//HCojY1qEmtCH+BvSFcqrR9maCiuZVIu zCwlX7CNxDP+8+2yQKPcSTGrKmU3CPbssa2GC1XfLl/y1H0scQyrQEvhsxhsWfsgLaFr eFizv5zwKqrWhCCWFTJx82GSwkWlv1Ekbr0fNTehhH60h2UrKZg9AmZVAQlN53UL7lLo Zy8WQc44foZvpLP25gmmk9xY51BAuWc5bTm5DtdJBv7nAkIsnm1zld2R0s17/07ZB+qy 3GHTkn9rR6eXE0gg/KygjYCbqBcJpSD4Nw9XfkMct8Q8cDDG8lgD205YPz3v1U3EmzFV J5Cw== X-Forwarded-Encrypted: i=1; AHgh+RobxHnSIT+bri5FDnEUuhj5lIVkfv6bs9uhSdy3pdZ4lDDOMfZTalGxCdtjozxl4Pexvc54ABsVUVE=@vger.kernel.org X-Gm-Message-State: AFuF++kEIPk5kzHckgz0AMmxA98pregdrfhbVehs//m75qTeMB6Jio43 RzdLrRM6QIfFakSPSKfAHeh0hI4+4c/hN+SMiB/8FvokpJsozeCEPD0kse9JOsq7+Br9sTg5j3n b2424YQ== X-Received: from pgbdm4.prod.google.com ([2002:a05:6a02:d84:b0:c79:39f0:12f2]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:1398:b0:3bf:8de9:c64e with SMTP id adf61e73a8af0-3ceed381cdcmr1617377637.2.1787684154733; Tue, 25 Aug 2026 11:55:54 -0700 (PDT) Date: Tue, 25 Aug 2026 11:55:54 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> <20260807-gmem-inplace-conversion-v10-9-2fc18ee6d3ba@google.com> <13ca60c6-e154-4397-8092-09f861e90fe0@kernel.org> <7eba513d-cdae-4832-abac-038dcdd88517@intel.com> Message-ID: Subject: Re: [PATCH v10 09/41] KVM: guest_memfd: Filter both shared and private when invalidating From: Sean Christopherson To: Michael Roth Cc: Xiaoyao Li , Ackerley Tng , Suzuki K Poulose , "David Hildenbrand (Arm)" , aik@amd.com, andrew.jones@linux.dev, binbin.wu@linux.intel.com, brauner@kernel.org, chao.p.peng@linux.intel.com, jmattson@google.com, jthoughton@google.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, aneesh.kumar@kernel.org, liam@infradead.org, Paolo Bonzini , 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 , tarunsahu@google.com, 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 Content-Type: text/plain; charset="us-ascii" On Tue, Aug 25, 2026, Michael Roth wrote: > On Wed, Aug 26, 2026 at 12:13:47AM +0800, Xiaoyao Li wrote: > > On 8/20/2026 9:32 AM, Sean Christopherson wrote: > > > And vice versa, a PUNCH_HOLE on a SHARED gmem (if userspace is > > > using an INIT_SHARED gmem for the shared branch of a memslot) could invalidate the > > > PRIVATE mappings (of a different gmem instance). > > > > I'm wondering now how this could happen. > > > > the requirement for PUNCH_HOLE on gmem to trigger mapping invalidation is > > the gmem is bound with the memslot. But how can a memslot bound with two > > gmem instances? > > I think this is for when userspace uses an mmap'able guest_memfd instance > to handle shared memory, and a 'normal' guest_memfd instance for private > memory. Each instance is bound to the same memslot/GPA range, and > KVM_SET_MEMORY_ATTRIBUTES handles switching between the 2. Yep, exactly.