Re: [RFC PATCH v1 14/38] coco: host: arm64: Device communication support

Jonathan Cameron
2025-07-30T13:52:58Z

On Mon, 28 Jul 2025 19:21:51 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org> wrote:

> Add helpers for device communication from RMM
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
> arch/arm64/include/asm/rmi_cmds.h | 11 ++
> arch/arm64/include/asm/rmi_smc.h | 49 ++++++
> drivers/virt/coco/arm-cca-host/arm-cca.c | 45 ++++++
> drivers/virt/coco/arm-cca-host/rmm-da.c | 198 +++++++++++++++++++++++
> drivers/virt/coco/arm-cca-host/rmm-da.h | 41 +++++
> 5 files changed, 344 insertions(+)
>

> #endif /* __ASM_RMI_CMDS_H */
> diff --git a/arch/arm64/include/asm/rmi_smc.h b/arch/arm64/include/asm/rmi_smc.h
> index a84ed61e5001..8bece465b670 100644
> --- a/arch/arm64/include/asm/rmi_smc.h
> +++ b/arch/arm64/include/asm/rmi_smc.h
> @@ -47,6 +47,7 @@

>
> +#define RMI_DEV_COMM_EXIT_CACHE_REQ BIT(0)
> +#define RMI_DEV_COMM_EXIT_CACHE_RSP BIT(1)
> +#define RMI_DEV_COMM_EXIT_SEND BIT(2)
> +#define RMI_DEV_COMM_EXIT_WAIT BIT(3)
> +#define RMI_DEV_COMM_EXIT_MULTI BIT(4)
> +
> +#define RMI_DEV_COMM_NONE 0
> +#define RMI_DEV_COMM_RESPONSE 1
> +#define RMI_DEV_COMM_ERROR 2
> +
> +#define RMI_PROTOCOL_SPDM 0
> +#define RMI_PROTOCOL_SECURE_SPDM 1
> +
> +#define RMI_DEV_VCA 0
> +#define RMI_DEV_CERTIFICATE 1
> +#define RMI_DEV_MEASUREMENTS 2
> +#define RMI_DEV_INTERFACE_REPORT 3
> +
> +struct rmi_dev_comm_enter {
> + u64 status;
> + u64 req_addr;
> + u64 resp_addr;
> + u64 resp_len;
> +};
> +
> +struct rmi_dev_comm_exit {
> + u64 flags;
> + u64 cache_req_offset;
> + u64 cache_req_len;
> + u64 cache_rsp_offset;
> + u64 cache_rsp_len;
> + u64 cache_obj_id;
> + u64 protocol;
> + u64 req_len;
> + u64 timeout;
In latest spec called rsp_timeout.
Not sure we care that much but if no strong reason otherwise, should
aim to match the spec text. (Maybe this got renamed?)
> +};

> diff --git a/drivers/virt/coco/arm-cca-host/arm-cca.c b/drivers/virt/coco/arm-cca-host/arm-cca.c
> index 84d97dd41191..294a6ef60d5f 100644
> --- a/drivers/virt/coco/arm-cca-host/arm-cca.c
> +++ b/drivers/virt/coco/arm-cca-host/arm-cca.c
> @@ -85,6 +85,45 @@ static void cca_tsm_pci_remove(struct pci_tsm *tsm)
> vfree(dsc_pf0);
> }
>
> +static int init_dev_communication_buffers(struct cca_host_comm_data *comm_data)
> +{
> + int ret = -ENOMEM;
> +
> + comm_data->io_params = (struct rmi_dev_comm_data *)get_zeroed_page(GFP_KERNEL);

Hmm. There isn't a DEFINE_FREE() yet for free_page(). Maybe time to add one.
If we did then we'd use local variables until all allocations succeed then
assign with no_free_ptr()

> + if (!comm_data->io_params)
> + goto err_out;
> +
> + comm_data->resp_buff = (void *)__get_free_page(GFP_KERNEL);
> + if (!comm_data->resp_buff)
> + goto err_res_buff;
> +
> + comm_data->req_buff = (void *)__get_free_page(GFP_KERNEL);
> + if (!comm_data->req_buff)
> + goto err_req_buff;
> +
> +
> + comm_data->io_params->enter.status = RMI_DEV_COMM_NONE;
> + comm_data->io_params->enter.resp_addr = virt_to_phys(comm_data->resp_buff);
> + comm_data->io_params->enter.req_addr = virt_to_phys((void *)comm_data->req_buff);
I think it's already a a void * and even if it were some other pointer type
no cast would be necessary.

> + comm_data->io_params->enter.resp_len = 0;
> +
> + return 0;
> +
> +err_req_buff:
> + free_page((unsigned long)comm_data->resp_buff);
> +err_res_buff:
> + free_page((unsigned long)comm_data->io_params);
> +err_out:
> + return ret;
> +}
> +

> +
> /* per root port unique with multiple restrictions. For now global */
> static DECLARE_BITMAP(cca_stream_ids, MAX_STREAM_ID);
>
> @@ -124,6 +163,7 @@ static int cca_tsm_connect(struct pci_dev *pdev)
> rc = tsm_ide_stream_register(pdev, ide);
> if (rc)
> goto err_tsm;
> + init_dev_communication_buffers(&dsc_pf0->comm_data);
> /*
> * Take a module reference so that we won't call unregister
> * without rme_unasign_device
> @@ -133,6 +173,11 @@ static int cca_tsm_connect(struct pci_dev *pdev)
> goto err_tsm;
> }
> rme_asign_device(pdev);
rme_assign_device() - I obviously missed this earlier!

> + /*
> + * Schedule a work to fetch device certificate and setup IDE
Single line comment probably fine here. Though it perhaps doesn't add
much over the function name.
> + */
> + schedule_rme_ide_setup(pdev);
> +
> /*
> * Once ide is setup enable the stream at endpoint
> * Root port will be done by RMM
> diff --git a/drivers/virt/coco/arm-cca-host/rmm-da.c b/drivers/virt/coco/arm-cca-host/rmm-da.c
> index 426e530ac182..d123940ce82e 100644
> --- a/drivers/virt/coco/arm-cca-host/rmm-da.c
> +++ b/drivers/virt/coco/arm-cca-host/rmm-da.c
> @@ -148,3 +148,201 @@ int rme_asign_device(struct pci_dev *pci_dev)
> err_out:
> return ret;
> }
> +
> +static int doe_send_req_resp(struct pci_tsm *tsm)
> +{
> + u8 protocol;
> + int ret, data_obj_type;
> + struct cca_host_comm_data *comm_data;
> + struct rmi_dev_comm_exit *io_exit;
> +
> + comm_data = to_cca_comm_data(tsm->pdev);
> +
> + io_exit = &comm_data->io_params->exit;
> + protocol = io_exit->protocol;

For all these I'd combine with the declarations.

> +
> + pr_debug("doe_req size:%lld doe_io_type=%d\n", io_exit->req_len, (int)protocol);
> +
> + if (protocol == RMI_PROTOCOL_SPDM)
> + data_obj_type = PCI_DOE_PROTO_CMA;
> + else if (protocol == RMI_PROTOCOL_SECURE_SPDM)
> + data_obj_type = PCI_DOE_PROTO_SSESSION;
> + else
> + return -EINVAL;
> +
> + ret = pci_tsm_doe_transfer(tsm->dsm_dev, data_obj_type,
> + comm_data->req_buff, io_exit->req_len,
> + comm_data->resp_buff, PAGE_SIZE);
> + pr_debug("doe returned:%d\n", ret);
> + return ret;
> +}
> +
> +/* Parallel update for cca_dsc contents FIXME!! */
> +static int __do_dev_communicate(int type, struct pci_tsm *tsm)
> +{
> + int ret;
> + bool is_multi;
> + u8 *cache_buf;
> + int *cache_offset;
> + int nbytes, cache_remaining;
> + struct cca_host_dsc_pf0 *dsc_pf0;
> + struct rmi_dev_comm_exit *io_exit;
> + struct rmi_dev_comm_enter *io_enter;
> + struct cca_host_comm_data *comm_data;
> +
> +
> + comm_data = to_cca_comm_data(tsm->pdev);
> + io_enter = &comm_data->io_params->enter;
> + io_exit = &comm_data->io_params->exit;

Might as well set these local variables as the declaration point
above. None of them will be very long lines.

> +
> + dsc_pf0 = to_cca_dsc_pf0(tsm->dsm_dev);
> +redo_communicate:
> + is_multi = false;
> +
> + if (type == PDEV_COMMUNICATE)
> + ret = rmi_pdev_communicate(virt_to_phys(dsc_pf0->rmm_pdev),
> + virt_to_phys(comm_data->io_params));
> + else
> + ret = RMI_ERROR_INPUT;

I'd split this case out and return here farther than using the match below
as it feels like the error message auto to be more specific. Something
about type not matching.

> + if (ret != RMI_SUCCESS) {
> + pr_err("pdev communicate error\n");
> + return ret;
> + }
> +
> + /* caching request from RMM */
> + if (io_exit->flags & RMI_DEV_COMM_EXIT_CACHE_RSP) {
> + switch (io_exit->cache_obj_id) {
> + case RMI_DEV_VCA:
> + cache_buf = dsc_pf0->vca.buf;
> + cache_offset = &dsc_pf0->vca.size;
> + cache_remaining = sizeof(dsc_pf0->vca.buf) - *cache_offset;
> + break;
> + case RMI_DEV_CERTIFICATE:
> + cache_buf = dsc_pf0->cert_chain.cache.buf;
> + cache_offset = &dsc_pf0->cert_chain.cache.size;
> + cache_remaining = sizeof(dsc_pf0->cert_chain.cache.buf) - *cache_offset;
> + break;
> + default:
> + /* FIXME!! depending on the DevComms status,
> + * it might require to ABORT the communcation.
> + */
> + return -EINVAL;
> + }
> +
> + if (io_exit->cache_rsp_len > cache_remaining)
> + return -EINVAL;
> +
> + memcpy(cache_buf + *cache_offset,
> + (comm_data->resp_buff + io_exit->cache_rsp_offset), io_exit->cache_rsp_len);
> + *cache_offset += io_exit->cache_rsp_len;
> + }
> +
> + /*
> + * wait for last packet request from RMM.
> + * We should not find this because our device communication in synchronous
> + */
> + if (io_exit->flags & RMI_DEV_COMM_EXIT_WAIT)
> + return -ENXIO;
> +
> + is_multi = !!(io_exit->flags & RMI_DEV_COMM_EXIT_MULTI);

!! doesn't add anything here that I can see over

is_multi = io_exit->flags & RMI_DEV_COMM_EXIT_MULTI;

> +
> + /* next packet to send */
> + if (io_exit->flags & RMI_DEV_COMM_EXIT_SEND) {
> + nbytes = doe_send_req_resp(tsm);
> + if (nbytes < 0) {
> + /* report error back to RMM */
> + io_enter->status = RMI_DEV_COMM_ERROR;
> + } else {
> + /* send response back to RMM */
> + io_enter->resp_len = nbytes;
> + io_enter->status = RMI_DEV_COMM_RESPONSE;
> + }
> + } else {
> + /* no data transmitted => no data received */
> + io_enter->resp_len = 0;
> + }
> +
> + /* The call need to do multiple request/respnse */
> + if (is_multi)
> + goto redo_communicate;
> +
> + return 0;
> +}
> +
> +static int do_dev_communicate(int type, struct pci_tsm *tsm, int target_state)
> +{
> + int ret;
> + unsigned long state;
> + unsigned long error_state;
> + struct cca_host_dsc_pf0 *dsc_pf0;
> + struct rmi_dev_comm_enter *io_enter;
> +
> + dsc_pf0 = to_cca_dsc_pf0(tsm->dsm_dev);
> + io_enter = &dsc_pf0->comm_data.io_params->enter;
> + io_enter->resp_len = 0;
> + io_enter->status = RMI_DEV_COMM_NONE;
> +
> + state = -1;
> + do {
> + ret = __do_dev_communicate(type, tsm);
> + if (ret != 0) {
if (ret)

> + pr_err("dev communication error\n");
> + break;

I'd just return in error cases.

> + }
> +
> + if (type == PDEV_COMMUNICATE) {
> + ret = rmi_pdev_get_state(virt_to_phys(dsc_pf0->rmm_pdev),
> + &state);
> + error_state = RMI_PDEV_ERROR;
> + }
> + if (ret != 0) {
> + pr_err("Get dev state error\n");
> + break;
> + }
> + } while (state != target_state && state != error_state);
> +
> + pr_info("dev_io_complete: status: %d state:%ld\n", ret, state);
> +
> + return state;
> +}