* [stable-5.4][PATCH] KVM: Forbid the use of tagged userspace addresses for memslots
@ 2021-02-01 13:31 Marc Zyngier
2021-02-01 13:38 ` Paolo Bonzini
0 siblings, 1 reply; 3+ messages in thread
From: Marc Zyngier @ 2021-02-01 13:31 UTC (permalink / raw)
To: stable; +Cc: Paolo Bonzini, gregkh, kvm, Rick Edgecombe, Catalin Marinas
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>
---
Documentation/virt/kvm/api.txt | 3 +++
virt/kvm/kvm_main.c | 1 +
2 files changed, 4 insertions(+)
diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
index a18e996fa54b..7064efd3b5ea 100644
--- a/Documentation/virt/kvm/api.txt
+++ b/Documentation/virt/kvm/api.txt
@@ -1132,6 +1132,9 @@ 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 8f3b40ec02b7..f25b5043cbca 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1017,6 +1017,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
/* We can read the guest memory with __xxx_user() later on. */
if ((id < KVM_USER_MEM_SLOTS) &&
((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)))
goto out;
--
2.29.2
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [stable-5.4][PATCH] KVM: Forbid the use of tagged userspace addresses for memslots
2021-02-01 13:31 [stable-5.4][PATCH] KVM: Forbid the use of tagged userspace addresses for memslots Marc Zyngier
@ 2021-02-01 13:38 ` Paolo Bonzini
2021-02-01 13:55 ` Greg KH
0 siblings, 1 reply; 3+ messages in thread
From: Paolo Bonzini @ 2021-02-01 13:38 UTC (permalink / raw)
To: Marc Zyngier, stable; +Cc: gregkh, kvm, Rick Edgecombe, Catalin Marinas
On 01/02/21 14:31, Marc Zyngier wrote:
> 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>
> ---
> Documentation/virt/kvm/api.txt | 3 +++
> virt/kvm/kvm_main.c | 1 +
> 2 files changed, 4 insertions(+)
>
> diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> index a18e996fa54b..7064efd3b5ea 100644
> --- a/Documentation/virt/kvm/api.txt
> +++ b/Documentation/virt/kvm/api.txt
> @@ -1132,6 +1132,9 @@ 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 8f3b40ec02b7..f25b5043cbca 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1017,6 +1017,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> /* We can read the guest memory with __xxx_user() later on. */
> if ((id < KVM_USER_MEM_SLOTS) &&
> ((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)))
> goto out;
>
Indeed untagged_addr was added in 5.3.
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Paolo
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [stable-5.4][PATCH] KVM: Forbid the use of tagged userspace addresses for memslots
2021-02-01 13:38 ` Paolo Bonzini
@ 2021-02-01 13:55 ` Greg KH
0 siblings, 0 replies; 3+ messages in thread
From: Greg KH @ 2021-02-01 13:55 UTC (permalink / raw)
To: Paolo Bonzini; +Cc: Marc Zyngier, stable, kvm, Rick Edgecombe, Catalin Marinas
On Mon, Feb 01, 2021 at 02:38:05PM +0100, Paolo Bonzini wrote:
> On 01/02/21 14:31, Marc Zyngier wrote:
> > 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>
> > ---
> > Documentation/virt/kvm/api.txt | 3 +++
> > virt/kvm/kvm_main.c | 1 +
> > 2 files changed, 4 insertions(+)
> >
> > diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> > index a18e996fa54b..7064efd3b5ea 100644
> > --- a/Documentation/virt/kvm/api.txt
> > +++ b/Documentation/virt/kvm/api.txt
> > @@ -1132,6 +1132,9 @@ 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 8f3b40ec02b7..f25b5043cbca 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1017,6 +1017,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > /* We can read the guest memory with __xxx_user() later on. */
> > if ((id < KVM_USER_MEM_SLOTS) &&
> > ((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)))
> > goto out;
> >
>
> Indeed untagged_addr was added in 5.3.
>
> Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Now queued up, thanks.
greg k-h
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2021-02-01 13:31 [stable-5.4][PATCH] KVM: Forbid the use of tagged userspace addresses for memslots Marc Zyngier
2021-02-01 13:38 ` Paolo Bonzini
2021-02-01 13:55 ` Greg KH
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