Hi Greg,
On 2021-02-01 12:41, gregkh@xxxxxxxxxxxxxxxxxxx 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@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 139bc8a6146d92822c866cf2fd410159c56b3648 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <maz@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Reported-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
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))
return -EINVAL;
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.
--
Jazz is not dead. It just smells funny...
