From: Sean Christopherson <[email protected]> Now that guest_memfd supports tracking private vs. shared within gmem itself, allow userspace to specify INIT_SHARED on a guest_memfd instance for x86 Confidential Computing (CoCo) VMs, so long as per-VM attributes are disabled, i.e. when it's actually possible for a guest_memfd instance to contain shared memory.
Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Ackerley Tng <[email protected]> --- arch/x86/kvm/x86.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 1560de1e95be0..6609957ecfea3 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -14172,14 +14172,13 @@ bool kvm_arch_no_poll(struct kvm_vcpu *vcpu) } #ifdef CONFIG_KVM_GUEST_MEMFD -/* - * KVM doesn't yet support initializing guest_memfd memory as shared for VMs - * with private memory (the private vs. shared tracking needs to be moved into - * guest_memfd). - */ bool kvm_arch_supports_gmem_init_shared(struct kvm *kvm) { - return !kvm_arch_has_private_mem(kvm); + /* + * INIT_SHARED isn't supported if the memory attributes are per-VM, + * in which case guest_memfd can _only_ be used for private memory. + */ + return !vm_memory_attributes || !kvm_arch_has_private_mem(kvm); } #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_PREPARE -- 2.54.0.545.g6539524ca2-goog
