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[2003:d8:2f27:ec00:4f4d:d38:ba97:9aa2]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3a5298a2c1esm2270925f8f.5.2025.06.05.10.35.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 05 Jun 2025 10:35:16 -0700 (PDT) Message-ID: <8782284c-0ffc-489d-adfe-b25d5ccb77b3@redhat.com> Date: Thu, 5 Jun 2025 19:35:14 +0200 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v11 12/18] KVM: x86: Enable guest_memfd shared memory for SW-protected VMs To: Fuad Tabba Cc: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev, pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com References: <20250605153800.557144-1-tabba@google.com> <20250605153800.557144-13-tabba@google.com> <4909d6dc-09f5-4960-b8be-5150b2a03e45@redhat.com> From: David Hildenbrand Content-Language: en-US Autocrypt: addr=david@redhat.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 05.06.25 18:11, Fuad Tabba wrote: > On Thu, 5 Jun 2025 at 16:49, David Hildenbrand wrote: >> >> On 05.06.25 17:37, Fuad Tabba wrote: >>> Define the architecture-specific macro to enable shared memory support >>> in guest_memfd for relevant software-only VM types, specifically >>> KVM_X86_DEFAULT_VM and KVM_X86_SW_PROTECTED_VM. >>> >>> Enable the KVM_GMEM_SHARED_MEM Kconfig option if KVM_SW_PROTECTED_VM is >>> enabled. >>> >>> Co-developed-by: Ackerley Tng >>> Signed-off-by: Ackerley Tng >>> Signed-off-by: Fuad Tabba >>> --- >>> arch/x86/include/asm/kvm_host.h | 10 ++++++++++ >>> arch/x86/kvm/Kconfig | 1 + >>> arch/x86/kvm/x86.c | 3 ++- >>> 3 files changed, 13 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h >>> index 709cc2a7ba66..ce9ad4cd93c5 100644 >>> --- a/arch/x86/include/asm/kvm_host.h >>> +++ b/arch/x86/include/asm/kvm_host.h >>> @@ -2255,8 +2255,18 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, >>> >>> #ifdef CONFIG_KVM_GMEM >>> #define kvm_arch_supports_gmem(kvm) ((kvm)->arch.supports_gmem) >>> + >>> +/* >>> + * CoCo VMs with hardware support that use guest_memfd only for backing private >>> + * memory, e.g., TDX, cannot use guest_memfd with userspace mapping enabled. >>> + */ >>> +#define kvm_arch_supports_gmem_shared_mem(kvm) \ >>> + (IS_ENABLED(CONFIG_KVM_GMEM_SHARED_MEM) && \ >>> + ((kvm)->arch.vm_type == KVM_X86_SW_PROTECTED_VM || \ >>> + (kvm)->arch.vm_type == KVM_X86_DEFAULT_VM)) >>> #else >>> #define kvm_arch_supports_gmem(kvm) false >>> +#define kvm_arch_supports_gmem_shared_mem(kvm) false >>> #endif >>> >>> #define kvm_arch_has_readonly_mem(kvm) (!(kvm)->arch.has_protected_state) >>> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig >>> index b37258253543..fdf24b50af9d 100644 >>> --- a/arch/x86/kvm/Kconfig >>> +++ b/arch/x86/kvm/Kconfig >>> @@ -47,6 +47,7 @@ config KVM_X86 >>> select KVM_GENERIC_HARDWARE_ENABLING >>> select KVM_GENERIC_PRE_FAULT_MEMORY >>> select KVM_GENERIC_GMEM_POPULATE if KVM_SW_PROTECTED_VM >>> + select KVM_GMEM_SHARED_MEM if KVM_SW_PROTECTED_VM >>> select KVM_WERROR if WERROR >> >> Is $subject and this still true, given that it's now also supported for >> KVM_X86_DEFAULT_VM? > > True, just not the whole truth :) > > I guess a better one would be, for Software VMs (remove protected)? Now I am curious, what is a Hardware VM? :) -- Cheers, David / dhildenb