From: Will Deacon Date: Mon, 30 Mar 2026 14:48:10 +0000 (+0100) Subject: KVM: arm64: Prevent unsupported memslot operations on protected VMs X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0877a1455cc6a93be14e4da741ce26ac0d6ca6d;p=thirdparty%2Fkernel%2Fstable.git KVM: arm64: Prevent unsupported memslot operations on protected VMs Protected VMs do not support deleting or moving memslots after first run nor do they support read-only or dirty logging. Return -EPERM to userspace if such an operation is attempted. Reviewed-by: Fuad Tabba Tested-by: Fuad Tabba Tested-by: Mostafa Saleh Signed-off-by: Will Deacon Link: https://patch.msgid.link/20260330144841.26181-10-will@kernel.org Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c index 5e7821fe0fc4..b3cc5dfe5723 100644 --- a/arch/arm64/kvm/mmu.c +++ b/arch/arm64/kvm/mmu.c @@ -2414,6 +2414,19 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, hva_t hva, reg_end; int ret = 0; + if (kvm_vm_is_protected(kvm)) { + /* Cannot modify memslots once a pVM has run. */ + if (pkvm_hyp_vm_is_created(kvm) && + (change == KVM_MR_DELETE || change == KVM_MR_MOVE)) { + return -EPERM; + } + + if (new && + new->flags & (KVM_MEM_LOG_DIRTY_PAGES | KVM_MEM_READONLY)) { + return -EPERM; + } + } + if (change != KVM_MR_CREATE && change != KVM_MR_MOVE && change != KVM_MR_FLAGS_ONLY) return 0; diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c index dd93dfdfe52d..94b70eb80aa8 100644 --- a/arch/arm64/kvm/pkvm.c +++ b/arch/arm64/kvm/pkvm.c @@ -192,10 +192,16 @@ int pkvm_create_hyp_vm(struct kvm *kvm) { int ret = 0; + /* + * Synchronise with kvm_arch_prepare_memory_region(), as we + * prevent memslot modifications on a pVM that has been run. + */ + mutex_lock(&kvm->slots_lock); mutex_lock(&kvm->arch.config_lock); if (!pkvm_hyp_vm_is_created(kvm)) ret = __pkvm_create_hyp_vm(kvm); mutex_unlock(&kvm->arch.config_lock); + mutex_unlock(&kvm->slots_lock); return ret; }