[RFC PATCH v4 10/16] coco: host: arm64: Add helper for cached object fetches

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

Introduce vdev_fetch_object_work() so we have a single workqueue handler
that refreshes any cached Realm object (interface report, measurements,
certificates). The helper receives the cache buffer/offset/size via
dev_comm_work, clears the existing contents under dsm_dev.object_lock,
performs the VDEV_COMMUNICATE call, and uses the updated size to signal
failures back to the caller once the work completes.

Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 drivers/virt/coco/arm-cca-host/rmi-da.c | 26 +++++++++++++++++++++++++
 drivers/virt/coco/arm-cca-host/rmi-da.h |  3 +++
 2 files changed, 29 insertions(+)

diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.c b/drivers/virt/coco/arm-cca-host/rmi-da.c
index 3db42c21dab0..63b20c8aef54 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.c
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.c
@@ -1138,6 +1138,32 @@ void cca_vdev_unlock_and_destroy(struct realm *realm,
 	host_tdi->realm = NULL;
 }
 
+static void __maybe_unused vdev_fetch_object_workfn(struct work_struct *work)
+{
+	int state;
+	struct pci_tsm *tsm;
+	struct cca_host_pdev_dsc *pdev_dsc;
+	struct dev_comm_work *setup_work;
+
+	setup_work = container_of(work, struct dev_comm_work, work);
+	tsm = setup_work->tsm;
+	pdev_dsc = to_cca_pdev_dsc(tsm->dsm_dev);
+
+	guard(mutex)(&pdev_dsc->object_lock);
+
+	if (setup_work->cache_size) {
+		memset(setup_work->cache_buf, 0, setup_work->cache_size);
+		*setup_work->cache_offset = 0;
+	}
+	state = do_dev_communicate(VDEV_COMMUNICATE, tsm, RMI_VDEV_ERROR, NULL);
+	/* return status through dev_comm_work.cache_cache */
+	if (state == RMI_VDEV_ERROR)
+		setup_work->cache_size = 0;
+	else
+		/* indicate success. This value is not used. */
+		setup_work->cache_size = CACHE_CHUNK_SIZE;
+}
+
 int cca_vdev_get_object_size(struct pci_dev *pdev, int type)
 {
 	long len;
diff --git a/drivers/virt/coco/arm-cca-host/rmi-da.h b/drivers/virt/coco/arm-cca-host/rmi-da.h
index 4f1a61a5dcfa..c1fc7c01943e 100644
--- a/drivers/virt/coco/arm-cca-host/rmi-da.h
+++ b/drivers/virt/coco/arm-cca-host/rmi-da.h
@@ -28,6 +28,9 @@ struct cache_object {
 struct dev_comm_work {
 	struct pci_tsm *tsm;
 	int target_state;
+	u8 *cache_buf;
+	int *cache_offset;
+	int cache_size;
 	struct work_struct work;
 };
 
-- 
2.43.0