Re: [PATCH 1/2] KVM: PPC: Book3S HV: check caller of H_SVM_* Hcalls

[Ram Pai]

On Fri, Mar 20, 2020 at 11:26:42AM +0100, Laurent Dufour wrote:
> The Hcall named H_SVM_* are reserved to the Ultravisor. However, nothing
> prevent a malicious VM or SVM to call them. This could lead to weird result
> and should be filtered out.
> 
> Checking the Secure bit of the calling MSR ensure that the call is coming
> from either the Ultravisor or a SVM. But any system call made from a SVM
> are going through the Ultravisor, and the Ultravisor should filter out
> these malicious call. This way, only the Ultravisor is able to make such a
> Hcall.
> 
> Cc: Bharata B Rao <bharata@xxxxxxxxxxxxx>
> Cc: Paul Mackerras <paulus@xxxxxxxxxx>
> Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>

Reviewed-by: Ram Pai <linuxram@xxxxxxxxxxx>

> ---
>  arch/powerpc/kvm/book3s_hv.c | 32 +++++++++++++++++++++-----------
>  1 file changed, 21 insertions(+), 11 deletions(-)
>