Re: [PATCH v2 1/4] KVM: arm64: Trap FFA_VERSION host call in pKVM

Sebastian Ene
2024-06-13T11:56:05Z

On Wed, Jun 12, 2024 at 02:58:31PM +0100, Sudeep Holla wrote:
> On Wed, May 15, 2024 at 05:22:55PM +0000, Sebastian Ene wrote:
> > The pKVM hypervisor initializes with FF-A version 1.0. The spec requires
> > that no other FF-A calls to be issued before the version negotiation
> > phase is complete. Split the hypervisor proxy initialization code in two
> > parts so that we can move the later one after the host negotiates its
> > version.
>
> Blank line here would be nice.
>

Added blank line.

> > Without trapping the call, the host drivers can negotiate a higher
> > version number with TEE which can result in a different memory layout
> > described during the memory sharing calls.
> >
>
> LGTM(apart from minor nits),
>
> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
>

Thanks Sudeep, I will incorporate the tag it in v3.

> > Signed-off-by: Sebastian Ene <sebastianene@google.com>
> > ---
> > arch/arm64/kvm/hyp/nvhe/ffa.c | 123 +++++++++++++++++++++++++---------
> > 1 file changed, 92 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > index 320f2eaa14a9..72f1206c85fb 100644
> > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c
> > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
> > @@ -1,4 +1,5 @@
> > // SPDX-License-Identifier: GPL-2.0-only
> > +//
>
> It should be OK but still spurious for $subject 😉
>
> [...]
>

Dropped this.

> > @@ -700,7 +789,6 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id)
> > int hyp_ffa_init(void *pages)
> > {
> > struct arm_smccc_res res;
> > - size_t min_rxtx_sz;
> > void *tx, *rx;
> >
> > if (kvm_host_psci_config.smccc_version < ARM_SMCCC_VERSION_1_2)
> > @@ -726,35 +814,7 @@ int hyp_ffa_init(void *pages)
> > if (FFA_MAJOR_VERSION(res.a0) != 1)
> > return -EOPNOTSUPP;
> >
> > - arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res);
> > - if (res.a0 != FFA_SUCCESS)
> > - return -EOPNOTSUPP;
> > -
> > - if (res.a2 != HOST_FFA_ID)
> > - return -EINVAL;
> > -
> > - arm_smccc_1_1_smc(FFA_FEATURES, FFA_FN64_RXTX_MAP,
> > - 0, 0, 0, 0, 0, 0, &res);
> > - if (res.a0 != FFA_SUCCESS)
> > - return -EOPNOTSUPP;
> > -
> > - switch (res.a2) {
> > - case FFA_FEAT_RXTX_MIN_SZ_4K:
> > - min_rxtx_sz = SZ_4K;
> > - break;
> > - case FFA_FEAT_RXTX_MIN_SZ_16K:
> > - min_rxtx_sz = SZ_16K;
> > - break;
> > - case FFA_FEAT_RXTX_MIN_SZ_64K:
> > - min_rxtx_sz = SZ_64K;
> > - break;
> > - default:
> > - return -EINVAL;
> > - }
> > -
> > - if (min_rxtx_sz > PAGE_SIZE)
> > - return -EOPNOTSUPP;
> > -
> > + hyp_ffa_version = FFA_VERSION_1_0;
> > tx = pages;
> > pages += KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE;
> > rx = pages;
> > @@ -773,8 +833,9 @@ int hyp_ffa_init(void *pages)
> > };
> >
> > host_buffers = (struct kvm_ffa_buffers) {
> > - .lock = __HYP_SPIN_LOCK_UNLOCKED,
> > + .lock = __HYP_SPIN_LOCK_UNLOCKED,
>
> Spurious or intentional whitespace change ? I can't make out from the mail.
>
> --

I dropped this, it was a spurious whitespace change.

> Regards,
> Sudeep

Cheers,
Seb