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X-CSE-ConnectionGUID: 0pI5h2alSSu5ytSa8Jw78w== X-CSE-MsgGUID: EU8WDN++RcKNco29SKwkGw== X-IronPort-AV: E=McAfee;i="6800,10657,11860"; a="86062841" X-IronPort-AV: E=Sophos;i="6.25,196,1779174000"; d="scan'208";a="86062841" Received: from fmviesa004.fm.intel.com ([10.60.135.144]) by orvoesa111.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2026 01:48:51 -0700 X-CSE-ConnectionGUID: u7DGKLPZS/eJ51NjhAIFwA== X-CSE-MsgGUID: ExP7CWv0QIW+0DfJQgeuiQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,196,1779174000"; d="scan'208";a="262491487" Received: from xiaoyaol-hp-g830.ccr.corp.intel.com (HELO [10.124.240.248]) ([10.124.240.248]) by fmviesa004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 31 Jul 2026 01:48:35 -0700 Message-ID: <7f23d149-b7f0-465a-a9c0-5c7484e289d2@intel.com> Date: Fri, 31 Jul 2026 16:48:29 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v9 20/41] KVM: Let userspace disable per-VM mem attributes, enable per-gmem attributes 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 , John Hubbard , Peter Xu , 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: <20260728-gmem-inplace-conversion-v9-0-35f9aec2aed2@google.com> <20260728-gmem-inplace-conversion-v9-20-35f9aec2aed2@google.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: <20260728-gmem-inplace-conversion-v9-20-35f9aec2aed2@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: C1C5C180006 X-Stat-Signature: kpxqxmyoydofqriih4qbxdonoee9xnfx X-HE-Tag: 1785487732-112563 X-HE-Meta: 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 TyEMTFFx fIyL74gYjBh7ek60dj0lwzyFplSYFwBPdWcmP0DO0xyWxjWh+5Zgr+SXUnYXwgXuB/y2TG0hoHbeRpp3W8v2G0XJYBd1Zho59tnE8GbyMF92JI/0uLTDwJyyTgOmvQ5BsBVdgqbJpG0o6oPuQfG/aI1JhL5KHjbCmQwDu8i41Qvhvsr+jnDsJMGMX400wYhpm97+lChEkAgCQtq2REgf6uXVlTqNoy22+ZqFOHfBeVtQmuq8RMXTlxjl8Iid7pMh8yYHigjQvMn2G6/JT25SJIQuTEQ+Y3rKCHkCuBDY/8WLsNVc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 7/29/2026 8:35 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 > read-only (0444). > > Since selecting CONFIG_KVM_VM_MEMORY_ATTRIBUTES disables in-place > conversion, 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 > Signed-off-by: Ackerley Tng > --- > arch/x86/include/asm/kvm_host.h | 4 +++- > arch/x86/kvm/Kconfig | 14 ++++++++++---- > virt/kvm/guest_memfd.c | 2 ++ > virt/kvm/kvm_main.c | 5 ++++- > 4 files changed, 19 insertions(+), 6 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index ceb2abf43b76f..766eb094eaae6 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1849,7 +1849,9 @@ 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/guest_memfd.c b/virt/kvm/guest_memfd.c > index ea2752989f8bd..df67a6188aa99 100644 > --- a/virt/kvm/guest_memfd.c > +++ b/virt/kvm/guest_memfd.c > @@ -1137,10 +1137,12 @@ static bool kvm_range_is_private(struct file *file, pgoff_t index, > { > struct inode *inode = file_inode(file); > > +#ifdef CONFIG_KVM_VM_MEMORY_ATTRIBUTES > 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); > +#endif > > return kvm_gmem_range_has_attributes(inode, index, nr_pages, > KVM_MEMORY_ATTRIBUTE_PRIVATE); With my suggestion[1] on patch 7, this diff block can be dropped. [1] https://lore.kernel.org/all/dd4201f2-3660-46ad-958f-c70feb1ab1c3@intel.com/ The code looks good to me, Reviewed-by: Xiaoyao Li > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index e961cc297ba2a..eb9f433278d2f 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -102,7 +102,10 @@ 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 > >