Messages in this thread Patch in this message | | | Date | Wed, 10 Apr 2024 16:57:19 +0200 | From | Lorenzo Pieralisi <> | Subject | Re: [PATCH] KVM: arm64: Add support for FFA_PARTITION_INFO_GET |
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On Tue, Apr 09, 2024 at 03:19:08PM +0000, Sebastian Ene wrote: > Handle the FFA_PARTITION_INFO_GET host call inside the pKVM hypervisor > and copy the response message back to the host buffers. Save the > returned FF-A version as we will need it later to interpret the response > from the TEE. > > Signed-off-by: Sebastian Ene <sebastianene@google.com> > --- > arch/arm64/kvm/hyp/nvhe/ffa.c | 49 +++++++++++++++++++++++++++++++++++ > 1 file changed, 49 insertions(+) > > diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c > index 320f2eaa14a9..72fc365bc7a8 100644 > --- a/arch/arm64/kvm/hyp/nvhe/ffa.c > +++ b/arch/arm64/kvm/hyp/nvhe/ffa.c > @@ -67,6 +67,7 @@ struct kvm_ffa_buffers { > */ > static struct kvm_ffa_buffers hyp_buffers; > static struct kvm_ffa_buffers host_buffers; > +static u32 ffa_version; > > static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno) > { > @@ -640,6 +641,49 @@ static bool do_ffa_features(struct arm_smccc_res *res, > return true; > } > > +static void do_ffa_part_get(struct arm_smccc_res *res, > + struct kvm_cpu_context *ctxt) > +{ > + DECLARE_REG(u32, uuid0, ctxt, 1); > + DECLARE_REG(u32, uuid1, ctxt, 2); > + DECLARE_REG(u32, uuid2, ctxt, 3); > + DECLARE_REG(u32, uuid3, ctxt, 4); > + DECLARE_REG(u32, flags, ctxt, 5); > + u32 off, count, sz, buf_sz; > + > + hyp_spin_lock(&host_buffers.lock); > + if (!host_buffers.rx) { > + ffa_to_smccc_res(res, FFA_RET_INVALID_PARAMETERS); > + goto out_unlock; > + } > + > + arm_smccc_1_1_smc(FFA_PARTITION_INFO_GET, uuid0, uuid1, > + uuid2, uuid3, flags, 0, 0, > + res); > + > + if (res->a0 != FFA_SUCCESS) > + goto out_unlock; > + > + count = res->a2; > + if (!count) > + goto out_unlock; > + > + if (ffa_version > FFA_VERSION_1_0) { > + buf_sz = sz = res->a3; > + if (sz > sizeof(struct ffa_partition_info)) > + buf_sz = sizeof(struct ffa_partition_info);
We are copying buf_sz but (correctly ?) returning res->a3 to the caller, which is allowed to expect res->a3 bytes to be filled since that's what firmware reported.
Technically this is not a problem at present, because the caller (ie the FF-A driver) and the hypervisor rely on the same descriptor structures (and buf_sz can't be != sizeof(struct ffa_partition_info), anything else is a bug as we stand); they must be kept in sync though as the firmware version changes (*if* there are changes in the partition descriptor - eg fields are added).
An option would consist in just copying res->a3 bytes as firmware reports (obviously keeping the RX buffer boundary checks for the memcpy).
It is just a heads-up because I noticed it, no more, I will let Sudeep comment on this since he knows better.
Lorenzo
> + } else { > + /* FFA_VERSION_1_0 lacks the size in the response */ > + buf_sz = sz = 8; > + } > + > + WARN_ON((count - 1) * sz + buf_sz > PAGE_SIZE); > + for (off = 0; off < count * sz; off += sz) > + memcpy(host_buffers.rx + off, hyp_buffers.rx + off, buf_sz); > +out_unlock: > + hyp_spin_unlock(&host_buffers.lock); > +} > + > bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) > { > struct arm_smccc_res res; > @@ -686,6 +730,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt, u32 func_id) > case FFA_MEM_FRAG_TX: > do_ffa_mem_frag_tx(&res, host_ctxt); > goto out_handled; > + case FFA_PARTITION_INFO_GET: > + do_ffa_part_get(&res, host_ctxt); > + break; > } > > if (ffa_call_supported(func_id)) > @@ -726,6 +773,8 @@ int hyp_ffa_init(void *pages) > if (FFA_MAJOR_VERSION(res.a0) != 1) > return -EOPNOTSUPP; > > + ffa_version = res.a0; > + > arm_smccc_1_1_smc(FFA_ID_GET, 0, 0, 0, 0, 0, 0, 0, &res); > if (res.a0 != FFA_SUCCESS) > return -EOPNOTSUPP; > -- > 2.44.0.478.gd926399ef9-goog >
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