From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.11]) (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 EEB9033938B; Fri, 14 Aug 2026 06:30:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786689046; cv=none; b=SXYALi1RyEFyMknmd52YvXXJDMn0BMnpT1tlgnFj9/xw7A9ZCpvELgav618Bx+V0kzlRB5mVvVqfBCuFE7UILLcqKfccDbmWlo8XKyvZwgNjKSYhTpFPaGpj3Tb1iEdmWUGia/7ZzF+kZ3lUNZtbo9YmlI4wMqmylyD3qOFKGa0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786689046; c=relaxed/simple; bh=lvF7pJW1VM34mjkgORqlnrodCT6IZU0t2OrgLf/yWf8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=tls+K1PHbNiKail8H61Et+lOl8G2MFg9DV4CCOrkfJtJ9fMZaZOHujXrclNp3w41fiOrKFyPGGqmXpOMlJORfxuuU/kvHQOjh+H7OqK27MrgSRRaJfYE7yzHufTsW/gbkQ4+OHqiLHj1VvQzIV5qrf6RIwI1zgHDMerSSlJ0a0g= 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=kQ7IW8DF; arc=none smtp.client-ip=192.198.163.11 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="kQ7IW8DF" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1786689044; x=1818225044; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=lvF7pJW1VM34mjkgORqlnrodCT6IZU0t2OrgLf/yWf8=; b=kQ7IW8DFgLX/G6UnC204lEgH5RYrAe15GlpDH434/7r0wUnr74bD0f+u J7Uf6VH2bnWYj6mX1SdLgg7GfvAGx6+HIWKJ+Q2Vo0yKM3I5ze9Gg2L1r qzIRxy8kDD9sC4u4YdtpjWht0SFzDbQt8Q+6KjBgdZY+pHdUVlWh+jSBQ HFfCeV0jVILNngbWGdm30ZHD55uEWQk8jXcBqf5mCv0E3Ex3IYzZGzv95 zobKO//Fkoihr42/m3deash/K7kC9tTYm3oqVJmnZPaTOFD3mDfyCXi6p EmLSfQqOneABR/I2bJbI1SzFe53C+gy0CycHmwAAxu460UFgvNaqVZ0he g==; X-CSE-ConnectionGUID: fCCMCUfeRqO027pG2/7MHg== X-CSE-MsgGUID: G4BjdzIITQGo5vX1VvWtnw== X-IronPort-AV: E=McAfee;i="6800,10657,11874"; a="97858860" X-IronPort-AV: E=Sophos;i="6.25,222,1779174000"; d="scan'208";a="97858860" Received: from fmviesa001.fm.intel.com ([10.60.135.141]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2026 23:30:41 -0700 X-CSE-ConnectionGUID: Dbj20DsZSw+g4w0B3MfgWw== X-CSE-MsgGUID: TWw3KlovS5Ot+mNiNFDdEg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,222,1779174000"; d="scan'208";a="288934258" Received: from binbinwu-mobl.ccr.corp.intel.com (HELO [10.124.245.162]) ([10.124.245.162]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Aug 2026 23:30:26 -0700 Message-ID: Date: Fri, 14 Aug 2026 14:30:23 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 20/41] KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes 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 , 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, Xiaoyao Li References: <20260807-gmem-inplace-conversion-v10-0-2fc18ee6d3ba@google.com> <20260807-gmem-inplace-conversion-v10-20-2fc18ee6d3ba@google.com> Content-Language: en-US From: Binbin Wu In-Reply-To: <20260807-gmem-inplace-conversion-v10-20-2fc18ee6d3ba@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 8/8/2026 5:52 AM, Ackerley Tng via B4 Relay wrote: > From: Ackerley Tng > > Make gmem_in_place_conversion a module parameter so that userspace can > configure enable or disable the use of VM-level memory attributes. The > module parameter is only available if CONFIG_KVM_VM_MEMORY_ATTRIBUTES is > enabled. > > To avoid inconsistencies in the way memory attributes are tracked in KVM > and guest_memfd, the vm_memory_attributes module_param is made The description is stale, since there is no module_param called vm_memory_attributes? > read-only (0444). > > Since selecting CONFIG_KVM_VM_MEMORY_ATTRIBUTES disables in-place > conversion, "selecting CONFIG_KVM_VM_MEMORY_ATTRIBUTES" doesn't necessarily disable in-place conversion, it also depends on the setting of gmem_in_place_conversion. To be accurate, maybe add "by default"? actually make CONFIG_KVM_VM_MEMORY_ATTRIBUTES selectable. Make > the config only selectable for (CoCo) VM types that might use > vm_memory_attributes. > > Since memory attributes are trackable in guest_memfd, the concept of having > private memory is no longer dependent on > CONFIG_KVM_VM_MEMORY_ATTRIBUTES. Define kvm_arch_has_private_mem() based on > platform config, so that having private memory is dependent on (CoCo) VM > type. > > Signed-off-by: Sean Christopherson > Reviewed-by: Fuad Tabba > Tested-by: Shivank Garg > [Define module_param only if CONFIG_KVM_VM_MEMORY_ATTRIBUTES is enabled] > Suggested-by: Xiaoyao Li > Reviewed-by: Xiaoyao Li > Signed-off-by: Ackerley Tng > --- > arch/x86/include/asm/kvm_host.h | 4 +++- > arch/x86/kvm/Kconfig | 14 ++++++++++---- > virt/kvm/kvm_main.c | 5 ++++- > 3 files changed, 17 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 497da6aaf2942..bb2c1ade62cf9 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1851,7 +1851,9 @@ enum kvm_intr_type { > ((vcpu) && (vcpu)->arch.handling_intr_from_guest && \ > (!!in_nmi() == ((vcpu)->arch.handling_intr_from_guest == KVM_HANDLING_NMI))) > > -#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES > +#if defined(CONFIG_KVM_SW_PROTECTED_VM) || \ > + defined(CONFIG_KVM_INTEL_TDX) || \ > + defined(CONFIG_KVM_AMD_SEV) > #define kvm_arch_has_private_mem(kvm) ((kvm)->arch.has_private_mem) > #endif > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > index abb108886733a..2c3c22aeafa54 100644 > --- a/arch/x86/kvm/Kconfig > +++ b/arch/x86/kvm/Kconfig > @@ -81,13 +81,21 @@ config KVM_WERROR > If in doubt, say "N". > > config KVM_VM_MEMORY_ATTRIBUTES > - bool > + bool "Enable per-VM PRIVATE vs. SHARED attributes (for CoCo VMs)" > + depends on KVM_SW_PROTECTED_VM || KVM_INTEL_TDX || KVM_AMD_SEV > + help > + Enable support for tracking PRIVATE vs. SHARED memory using per-VM > + memory attributes. Using per-VM attributes is deprecated in favor of > + tracking PRIVATE state in guest_memfd. Select this if you need to run > + CoCo VMs using a VMM that doesn't support guest_memfd memory > + attributes. > + > + If unsure, say N. > > config KVM_SW_PROTECTED_VM > bool "Enable support for KVM software-protected VMs" > depends on EXPERT > depends on KVM_X86 && X86_64 > - select KVM_VM_MEMORY_ATTRIBUTES > help > Enable support for KVM software-protected VMs. Currently, software- > protected VMs are purely a development and testing vehicle for > @@ -138,7 +146,6 @@ config KVM_INTEL_TDX > bool "Intel Trust Domain Extensions (TDX) support" > default y > depends on INTEL_TDX_HOST > - select KVM_VM_MEMORY_ATTRIBUTES > select HAVE_KVM_ARCH_GMEM_POPULATE > help > Provides support for launching Intel Trust Domain Extensions (TDX) > @@ -162,7 +169,6 @@ config KVM_AMD_SEV > depends on KVM_AMD && X86_64 > depends on CRYPTO_DEV_SP_PSP && !(KVM_AMD=y && CRYPTO_DEV_CCP_DD=m) > select ARCH_HAS_CC_PLATFORM > - select KVM_VM_MEMORY_ATTRIBUTES > select HAVE_KVM_ARCH_GMEM_CONVERT > select HAVE_KVM_ARCH_GMEM_RECLAIM > select HAVE_KVM_ARCH_GMEM_INVALIDATE > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index c8faf1cb82167..85dfc3f5af805 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -103,7 +103,10 @@ static bool __ro_after_init allow_unsafe_mappings; > module_param(allow_unsafe_mappings, bool, 0444); > > #ifdef kvm_arch_has_private_mem > -bool __ro_after_init gmem_in_place_conversion = false; > +bool __ro_after_init gmem_in_place_conversion = !IS_ENABLED(CONFIG_KVM_VM_MEMORY_ATTRIBUTES); > +#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES > +module_param(gmem_in_place_conversion, bool, 0444); > +#endif > EXPORT_SYMBOL_FOR_KVM_INTERNAL(gmem_in_place_conversion); > #endif > >