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charset="UTF-8" X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: DDDDD40018 X-Stat-Signature: sj317ua7h8jnudnjkr5qn9bx5bk7p6jr X-HE-Tag: 1752058819-103428 X-HE-Meta: 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 rL21+QwA 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Enable host userspace mmap support for guest_memfd-backed memory when running KVM with the KVM_X86_DEFAULT_VM type: * Define kvm_arch_supports_gmem_mmap() for KVM_X86_DEFAULT_VM: Introduce the architecture-specific kvm_arch_supports_gmem_mmap() macro, specifically enabling mmap support for KVM_X86_DEFAULT_VM instances. This macro, gated by CONFIG_KVM_GMEM_SUPPORTS_MMAP, ensures that only the default VM type can leverage guest_memfd mmap functionality on x86. This explicit enablement prevents CoCo VMs, which use guest_memfd primarily for private memory and rely on hardware-enforced privacy, from accidentally exposing guest memory via host userspace mappings. * Select CONFIG_KVM_GMEM_SUPPORTS_MMAP in KVM_X86: Enable the CONFIG_KVM_GMEM_SUPPORTS_MMAP Kconfig option when KVM_X86 is selected. This ensures that the necessary code for guest_memfd mmap support (introduced earlier) is compiled into the kernel for x86. This Kconfig option acts as a system-wide gate for the guest_memfd mmap capability. It implicitly enables CONFIG_KVM_GMEM, making guest_memfd available, and then layers the mmap capability on top specifically for the default VM. These changes make guest_memfd a more versatile memory backing for standard KVM guests, allowing VMMs to use a unified guest_memfd model for both private (CoCo) and non-private (default) VMs. This is a prerequisite for use cases such as running Firecracker guests entirely backed by guest_memfd and implementing direct map removal for non-CoCo VMs. Co-developed-by: Ackerley Tng Signed-off-by: Ackerley Tng Signed-off-by: Fuad Tabba --- arch/x86/include/asm/kvm_host.h | 9 +++++++++ arch/x86/kvm/Kconfig | 1 + arch/x86/kvm/x86.c | 3 ++- 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 4c764faa12f3..4c89feaa1910 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2273,9 +2273,18 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, #ifdef CONFIG_KVM_GMEM #define kvm_arch_has_private_mem(kvm) ((kvm)->arch.has_private_mem) #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_mmap(kvm) \ + (IS_ENABLED(CONFIG_KVM_GMEM_SUPPORTS_MMAP) && \ + (kvm)->arch.vm_type == KVM_X86_DEFAULT_VM) #else #define kvm_arch_has_private_mem(kvm) false #define kvm_arch_supports_gmem(kvm) false +#define kvm_arch_supports_gmem_mmap(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 df1fdbb4024b..239637b663dc 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_SUPPORTS_MMAP select KVM_WERROR if WERROR config KVM diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b34236029383..17c655e5716e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -12779,7 +12779,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) kvm->arch.vm_type = type; kvm->arch.has_private_mem = (type == KVM_X86_SW_PROTECTED_VM); - kvm->arch.supports_gmem = (type == KVM_X86_SW_PROTECTED_VM); + kvm->arch.supports_gmem = + type == KVM_X86_DEFAULT_VM || type == KVM_X86_SW_PROTECTED_VM; /* Decided by the vendor code for other VM types. */ kvm->arch.pre_fault_allowed = type == KVM_X86_DEFAULT_VM || type == KVM_X86_SW_PROTECTED_VM; -- 2.50.0.727.gbf7dc18ff4-goog