[PATCH v2 07/10] KVM: arm64: Handle FFA_MEM_RECLAIM calls from the host

Will Deacon
2023-04-19T12:22:48Z

Intecept FFA_MEM_RECLAIM calls from the host and transition the host
stage-2 page-table entries from the SHARED_OWNED state back to the OWNED
state once EL3 has confirmed that the secure mapping has been reclaimed.

Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kvm/hyp/nvhe/ffa.c | 79 +++++++++++++++++++++++++++++++++++
1 file changed, 79 insertions(+)

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index 95bc70e52e91..b23e3869ce63 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -124,6 +124,23 @@ static void spmd_mem_share(struct arm_smccc_res *res, u32 len, u32 fraglen)
res);
}

+static void spmd_mem_reclaim(struct arm_smccc_res *res, u32 handle_lo,
+ u32 handle_hi, u32 flags)
+{
+ arm_smccc_1_1_smc(FFA_MEM_RECLAIM,
+ handle_lo, handle_hi, flags,
+ 0, 0, 0, 0,
+ res);
+}
+
+static void spmd_retrieve_req(struct arm_smccc_res *res, u32 len)
+{
+ arm_smccc_1_1_smc(FFA_FN64_MEM_RETRIEVE_REQ,
+ len, len,
+ 0, 0, 0, 0, 0,
+ res);
+}
+
static void do_ffa_rxtx_map(struct arm_smccc_res *res,
struct kvm_cpu_context *ctxt)
{
@@ -375,6 +392,65 @@ static void do_ffa_mem_share(struct arm_smccc_res *res,
return;
}

+static void do_ffa_mem_reclaim(struct arm_smccc_res *res,
+ struct kvm_cpu_context *ctxt)
+{
+ DECLARE_REG(u32, handle_lo, ctxt, 1);
+ DECLARE_REG(u32, handle_hi, ctxt, 2);
+ DECLARE_REG(u32, flags, ctxt, 3);
+ struct ffa_composite_mem_region *reg;
+ struct ffa_mem_region *buf;
+ int ret = 0;
+ u32 offset;
+ u64 handle;
+
+ handle = PACK_HANDLE(handle_lo, handle_hi);
+
+ hyp_spin_lock(&host_buffers.lock);
+
+ buf = hyp_buffers.tx;
+ *buf = (struct ffa_mem_region) {
+ .sender_id = HOST_FFA_ID,
+ .handle = handle,
+ };
+
+ spmd_retrieve_req(res, sizeof(*buf));
+ buf = hyp_buffers.rx;
+ if (res->a0 != FFA_MEM_RETRIEVE_RESP)
+ goto out_unlock;
+
+ /* Check for fragmentation */
+ if (res->a1 != res->a2) {
+ ret = FFA_RET_ABORTED;
+ goto out_unlock;
+ }
+
+ offset = buf->ep_mem_access[0].composite_off;
+ /*
+ * We can trust the SPMD to get this right, but let's at least
+ * check that we end up with something that doesn't look _completely_
+ * bogus.
+ */
+ if (WARN_ON(offset > KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE)) {
+ ret = FFA_RET_ABORTED;
+ goto out_unlock;
+ }
+
+ reg = (void *)buf + offset;
+ spmd_mem_reclaim(res, handle_lo, handle_hi, flags);
+ if (res->a0 != FFA_SUCCESS)
+ goto out_unlock;
+
+ /* If the SPMD was happy, then we should be too. */
+ WARN_ON(ffa_host_unshare_ranges(reg->constituents,
+ reg->addr_range_cnt));
+out_unlock:
+ hyp_spin_unlock(&host_buffers.lock);
+
+ if (ret)
+ ffa_to_smccc_res(res, ret);
+}
+
/*
* Is a given FFA function supported, either by forwarding on directly
* or by handling at EL2?
@@ -428,6 +504,9 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
case FFA_FN64_MEM_SHARE:
do_ffa_mem_share(&res, host_ctxt);
goto out_handled;
+ case FFA_MEM_RECLAIM:
+ do_ffa_mem_reclaim(&res, host_ctxt);
+ goto out_handled;
}

if (ffa_call_supported(func_id))