[PATCH v2 09/10] KVM: arm64: Handle FFA_FEATURES call from the host

Will Deacon
2023-04-19T12:23:00Z

From: Fuad Tabba <tabba@google.com>

Filter out advertising unsupported features, and only advertise
features and properties that are supported by the hypervisor proxy.

Signed-off-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/hyp/nvhe/ffa.c | 45 +++++++++++++++++++++++++++++++----
1 file changed, 41 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 45a2726d73ff..aa8bfc97a164 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -64,15 +64,21 @@ static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
};
}

-static void ffa_to_smccc_res(struct arm_smccc_res *res, int ret)
+static void ffa_to_smccc_res_prop(struct arm_smccc_res *res, int ret, u64 prop)
{
if (ret == FFA_RET_SUCCESS) {
- *res = (struct arm_smccc_res) { .a0 = FFA_SUCCESS };
+ *res = (struct arm_smccc_res) { .a0 = FFA_SUCCESS,
+ .a2 = prop };
} else {
ffa_to_smccc_error(res, ret);
}
}

+static void ffa_to_smccc_res(struct arm_smccc_res *res, int ret)
+{
+ ffa_to_smccc_res_prop(res, ret, 0);
+}
+
static void ffa_set_retval(struct kvm_cpu_context *ctxt,
struct arm_smccc_res *res)
{
@@ -480,14 +486,41 @@ static bool ffa_call_supported(u64 func_id)
case FFA_RXTX_MAP:
case FFA_MEM_DONATE:
case FFA_MEM_RETRIEVE_REQ:
- /* Don't advertise any features just yet */
- case FFA_FEATURES:
return false;
}

return true;
}

+static bool do_ffa_features(struct arm_smccc_res *res,
+ struct kvm_cpu_context *ctxt)
+{
+ DECLARE_REG(u32, id, ctxt, 1);
+ u64 prop = 0;
+ int ret = 0;
+
+ if (!ffa_call_supported(id)) {
+ ret = FFA_RET_NOT_SUPPORTED;
+ goto out_handled;
+ }
+
+ switch (id) {
+ case FFA_MEM_SHARE:
+ case FFA_FN64_MEM_SHARE:
+ case FFA_MEM_LEND:
+ case FFA_FN64_MEM_LEND:
+ ret = FFA_RET_SUCCESS;
+ prop = 0; /* No support for dynamic buffers */
+ goto out_handled;
+ default:
+ return false;
+ }
+
+out_handled:
+ ffa_to_smccc_res_prop(res, ret, prop);
+ return true;
+}
+
bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
{
DECLARE_REG(u64, func_id, host_ctxt, 0);
@@ -497,6 +530,10 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
return false;

switch (func_id) {
+ case FFA_FEATURES:
+ if (!do_ffa_features(&res, host_ctxt))
+ return false;
+ goto out_handled;
/* Memory management */
case FFA_FN64_RXTX_MAP:
do_ffa_rxtx_map(&res, host_ctxt);