Re: [PATCH v3] KVM: arm64: Add memory length checks and remove inline in do_ffa_mem_xfer

[Oliver Upton]

On Wed, Sep 11, 2024 at 12:32:29AM +0800, Wei-Lin Chang wrote:
> Hi everyone,
> 
> On Mon, Sep 09, 2024 at 06:01:54PM GMT, Snehal Koukuntla wrote:
> > When we share memory through FF-A and the description of the buffers
> > exceeds the size of the mapped buffer, the fragmentation API is used.
> > The fragmentation API allows specifying chunks of descriptors in subsequent
> > FF-A fragment calls and no upper limit has been established for this.
> > The entire memory region transferred is identified by a handle which can be
> > used to reclaim the transferred memory.
> > To be able to reclaim the memory, the description of the buffers has to fit
> > in the ffa_desc_buf.
> > Add a bounds check on the FF-A sharing path to prevent the memory reclaim
> > from failing.
> > 
> > Also do_ffa_mem_xfer() does not need __always_inline
> > 
> > Fixes: 634d90cf0ac65 ("KVM: arm64: Handle FFA_MEM_LEND calls from the host")
> > Cc: stable@xxxxxxxxxxxxxxx
> > Reviewed-by: Sebastian Ene <sebastianene@xxxxxxxxxx>
> > Signed-off-by: Snehal Koukuntla <snehalreddy@xxxxxxxxxx>
> > ---
> >  arch/arm64/kvm/hyp/nvhe/ffa.c | 7 ++++++-
> >  1 file changed, 6 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > index e715c157c2c4..637425f63fd1 100644
> > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > @@ -426,7 +426,7 @@ static void do_ffa_mem_frag_tx(struct arm_smccc_res *res,
> >  	return;
> >  }
> >  
> > -static __always_inline void do_ffa_mem_xfer(const u64 func_id,
> > +static void do_ffa_mem_xfer(const u64 func_id,
> 
> I am seeing a compilation error because of this.

Thanks for reporting this. Looks like the __always_inline was slightly
more load bearing...

Marc, can you put something like this on top?