linux-kernel - Re: [PATCH 1/2] KVM: PPC: Book3S HV: check caller of H_SVM

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Message-Id: <20200321004044.GA5243@oc0525413822.ibm.com>
Date:   Fri, 20 Mar 2020 17:40:44 -0700
From:   Ram Pai <linuxram@...ibm.com>
To:     Laurent Dufour <ldufour@...ux.ibm.com>
Cc:     linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        kvm-ppc@...r.kernel.org, Bharata B Rao <bharata@...ux.ibm.com>
Subject: Re:  [PATCH 1/2] KVM: PPC: Book3S HV: check caller of H_SVM_* Hcalls

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@...ux.ibm.com>
> Cc: Paul Mackerras <paulus@...abs.org>
> Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>

Reviewed-by: Ram Pai <linuxram@...ibnm.com>

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