KVM: arm64: Allocate pages for hypervisor FF-A mailboxes

The FF-A proxy code needs to allocate its own buffer pair for
communication with EL3 and for forwarding calls from the host at EL1.

Reserve a couple of pages for this purpose and use them to initialise
the hypervisor's FF-A buffer structure.

Co-developed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230523101828.7328-4-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

1 files changed, 23 insertions, 1 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index abdcaf98d9b0..c85e5d46a90d 100644
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -28,8 +28,11 @@
 
 #include <linux/arm-smccc.h>
 #include <linux/arm_ffa.h>
+#include <asm/kvm_pkvm.h>
+
 #include <nvhe/ffa.h>
 #include <nvhe/trap_handler.h>
+#include <nvhe/spinlock.h>
 
 /*
  * "ID value 0 must be returned at the Non-secure physical FF-A instance"
@@ -37,6 +40,19 @@
  */
 #define HOST_FFA_ID	0
 
+struct kvm_ffa_buffers {
+	hyp_spinlock_t lock;
+	void *tx;
+	void *rx;
+};
+
+/*
+ * Note that we don't currently lock these buffers explicitly, instead
+ * relying on the locking of the host FFA buffers as we only have one
+ * client.
+ */
+static struct kvm_ffa_buffers hyp_buffers;
+
 static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
 {
 	*res = (struct arm_smccc_res) {
@@ -124,7 +140,7 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
 	return true;
 }
 
-int hyp_ffa_init(void)
+int hyp_ffa_init(void *pages)
 {
 	struct arm_smccc_res res;
 
@@ -145,5 +161,11 @@ int hyp_ffa_init(void)
 	if (res.a2 != HOST_FFA_ID)
 		return -EINVAL;
 
+	hyp_buffers = (struct kvm_ffa_buffers) {
+		.lock	= __HYP_SPIN_LOCK_UNLOCKED,
+		.tx	= pages,
+		.rx	= pages + (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE),
+	};
+
 	return 0;
 }