Hi Greg,
On 2021-02-01 12:41, gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 139bc8a6146d92822c866cf2fd410159c56b3648 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
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
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 4e5316ed10e9..c347b7083abf 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -1269,6 +1269,9 @@ 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 2541a17ff1c4..a9abaf5f8e53 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1290,6 +1290,7 @@ 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))
I'll post a revised patch for 5.4. No need to go beyond that as that's the point where we allowed tagged addresses at the syscall boundary.
Thanks,
M.