From 256a0040c6c9f6d342044897e33f280426a4e315 Mon Sep 17 00:00:00 2001 From: Marc Zyngier <maz@kernel.org> Date: Thu, 21 Jan 2021 12:08:15 +0000 Subject: [PATCH] KVM: Forbid the use of tagged userspace addresses for memslots commit 139bc8a6146d92822c866cf2fd410159c56b3648 upstream. The use of a tagged address could be pretty confusing for the whole memslot infrastructure as well as the MMU notifiers. Forbid it altogether, as it never quite worked the first place. Cc: stable@vger.kernel.org Reported-by: Rick Edgecombe <rick.p.edgecombe@intel.com> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Marc Zyngier <maz@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- Documentation/virt/kvm/api.rst | 3 +++ virt/kvm/kvm_main.c | 1 + 2 files changed, 4 insertions(+) diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index e00a66d7237285..de70ba5ff8d332 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1264,6 +1264,9 @@ field userspace_addr, which must point at user addressable memory for the entire memory slot size. Any object may back this memory, including anonymous memory, ordinary files, and hugetlbfs. +On architectures that support a form of address tagging, userspace_addr must +be an untagged address. + It is recommended that the lower 21 bits of guest_phys_addr and userspace_addr be identical. This allows large pages in the guest to be backed by large pages in the host. diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 3083fb53861dfe..cf9cc0ed7e9955 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1289,6 +1289,7 @@ int __kvm_set_memory_region(struct kvm *kvm, return -EINVAL; /* We can read the guest memory with __xxx_user() later on. */ if ((mem->userspace_addr & (PAGE_SIZE - 1)) || + (mem->userspace_addr != untagged_addr(mem->userspace_addr)) || !access_ok((void __user *)(unsigned long)mem->userspace_addr, mem->memory_size)) return -EINVAL; -- GitLab