Re: [RFC PATCH v1 13/38] coco: host: arm64: Create a PDEV with rmm

Jonathan Cameron
2025-07-30T12:40:09Z

On Mon, 28 Jul 2025 19:21:50 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org> wrote:

> Create the realm physical device with RMM.
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
Hi Aneesh,

Various small things inline.

Jonathan

> ---
> arch/arm64/include/asm/rmi_cmds.h | 31 +++++
> arch/arm64/include/asm/rmi_smc.h | 72 ++++++++++-
> drivers/virt/coco/arm-cca-host/Makefile | 2 +-
> drivers/virt/coco/arm-cca-host/arm-cca.c | 10 +-
> drivers/virt/coco/arm-cca-host/rmm-da.c | 150 +++++++++++++++++++++++
> drivers/virt/coco/arm-cca-host/rmm-da.h | 5 +
> 6 files changed, 267 insertions(+), 3 deletions(-)
> create mode 100644 drivers/virt/coco/arm-cca-host/rmm-da.c
>
> diff --git a/arch/arm64/include/asm/rmi_cmds.h b/arch/arm64/include/asm/rmi_cmds.h
> index ef53147c1984..f0817bd3bab4 100644
> --- a/arch/arm64/include/asm/rmi_cmds.h
> +++ b/arch/arm64/include/asm/rmi_cmds.h
> @@ -505,4 +505,35 @@ static inline int rmi_rtt_unmap_unprotected(unsigned long rd,
> return res.a0;
> }
>
> +static inline unsigned long rmi_pdev_aux_count(unsigned long flags, u64 *aux_count)
> +{
> + struct arm_smccc_res res;
> +
> + arm_smccc_1_1_invoke(SMC_RMI_PDEV_AUX_COUNT, flags, &res);
> +
> + *aux_count = res.a1;
> + return res.a0;
> +}
> +
> +static inline unsigned long rmi_pdev_create(unsigned long pdev_phys,
> + unsigned long pdev_params_phys)
> +{
> + struct arm_smccc_res res;
> +
> + arm_smccc_1_1_invoke(SMC_RMI_PDEV_CREATE,
> + pdev_phys, pdev_params_phys, &res);
> +
> + return res.a0;
> +}
> +
> +static inline unsigned long rmi_pdev_get_state(unsigned long pdev_phys, unsigned long *state)

I'd use the enum for the state type and range check in here.

> +{
> + struct arm_smccc_res res;
> +
> + arm_smccc_1_1_invoke(SMC_RMI_PDEV_GET_STATE, pdev_phys, &res);
> +
> + *state = res.a1;
> + return res.a0;
> +}
> +
> #endif /* __ASM_RMI_CMDS_H */
> diff --git a/arch/arm64/include/asm/rmi_smc.h b/arch/arm64/include/asm/rmi_smc.h
> index 42708d500048..a84ed61e5001 100644
> --- a/arch/arm64/include/asm/rmi_smc.h
> +++ b/arch/arm64/include/asm/rmi_smc.h
> @@ -26,7 +26,7 @@
> #define SMC_RMI_DATA_CREATE SMC_RMI_CALL(0x0153)
> #define SMC_RMI_DATA_CREATE_UNKNOWN SMC_RMI_CALL(0x0154)
> #define SMC_RMI_DATA_DESTROY SMC_RMI_CALL(0x0155)
> -

Probably keep

> +#define SMC_RMI_PDEV_AUX_COUNT SMC_RMI_CALL(0x0156)

and add one here as different groups.

> #define SMC_RMI_REALM_ACTIVATE SMC_RMI_CALL(0x0157)
> #define SMC_RMI_REALM_CREATE SMC_RMI_CALL(0x0158)
> #define SMC_RMI_REALM_DESTROY SMC_RMI_CALL(0x0159)
> @@ -47,6 +47,9 @@
> #define SMC_RMI_RTT_INIT_RIPAS SMC_RMI_CALL(0x0168)
> #define SMC_RMI_RTT_SET_RIPAS SMC_RMI_CALL(0x0169)
>
> +#define SMC_RMI_PDEV_CREATE SMC_RMI_CALL(0x0176)
> +#define SMC_RMI_PDEV_GET_STATE SMC_RMI_CALL(0x0178)
> +
> #define RMI_ABI_MAJOR_VERSION 1
> #define RMI_ABI_MINOR_VERSION 0
>
> @@ -268,4 +271,71 @@ struct rec_run {
> struct rec_exit exit;
> };
>
> +enum rmi_pdev_state {
Type never used, but I think it should be. See above.

> + RMI_PDEV_NEW,
> + RMI_PDEV_NEEDS_KEY,
> + RMI_PDEV_HAS_KEY,
> + RMI_PDEV_READY,
Seems someone put another state in here, but I guess you'll update
when the rest of the stack catches up.
RMI_PDEV_IDE_RESETTING,

Maybe throw a comment here for now.

> + RMI_PDEV_COMMUNICATING,
> + RMI_PDEV_STOPPING,
> + RMI_PDEV_STOPPED,
> + RMI_PDEV_ERROR,
> +};
> +
> +#define MAX_PDEV_AUX_GRANULES 32
> +#define MAX_IOCOH_ADDR_RANGE 16
> +#define MAX_FCOH_ADDR_RANGE 4
> +
> +#define RMI_PDEV_SPDM_TRUE BIT(0)
> +#define RMI_PDEV_IDE_TRUE BIT(1)
> +#define RMI_PDEV_FOCOH BIT(2)
> +#define RMI_PDEV_P2P_STREAM BIT(3)

I'd stick flags in the name (assuming this is
RmiPDevFlags? I'm not sure as the spec I could
find has different usages other after BIT(!))

> +
> +#define RMI_HASH_SHA_256 0
> +#define RMI_HASH_SHA_512 1
> +
> +struct rmi_pdev_addr_range {
> + unsigned long base;
> + unsigned long top;

Whilst we only care about platforms where this is u64, maybe
just make that explicit so we can trivially see this
matches the spec?

> +};
> +
> +struct rmi_pdev_params {

Reference? Looks like B4.4.25 RmiPdevParams type
in alp15. Though as there are some fields missing
I guess this chagned.

> + union {
> + struct {
> + u64 flags;
> + u64 pdev_id;
> + u64 segment_id;
> + u64 ecam_addr;
> + u64 root_id;
> + u64 cert_id;
> + u64 rid_base;
> + u64 rid_top;
> + u64 hash_algo;
> + u64 num_aux;
> + u64 ide_sid;

Called ncoh_ide_side in the alpha 15. Maybe match that unless
it is changing name in future version.

> + u64 ncoh_num_addr_range;
> + u64 coh_num_addr_range;
> + };
> + u8 padding1[0x100];
> + };
> +
> + union { /* 0x100 */
> + u64 aux_granule[MAX_PDEV_AUX_GRANULES];
> + u8 padding2[0x100];
> + };
> +
> + union { /* 0x200 */
> + struct {
> + struct rmi_pdev_addr_range ncoh_addr_range[MAX_IOCOH_ADDR_RANGE];
> + };
> + u8 padding3[0x100];
> + };
> + union { /* 0x300 */
> + struct {
> + struct rmi_pdev_addr_range coh_addr_range[MAX_FCOH_ADDR_RANGE];
> + };
> + u8 padding4[0x100];
> + };

Maybe pad out the rest? Mostly so we can see here that it is 4k.

> +};
> +
> #endif /* __ASM_RMI_SMC_H */

> diff --git a/drivers/virt/coco/arm-cca-host/arm-cca.c b/drivers/virt/coco/arm-cca-host/arm-cca.c
> index c8b0e6db1f47..84d97dd41191 100644
> --- a/drivers/virt/coco/arm-cca-host/arm-cca.c
> +++ b/drivers/virt/coco/arm-cca-host/arm-cca.c
> @@ -124,7 +124,15 @@ static int cca_tsm_connect(struct pci_dev *pdev)
> rc = tsm_ide_stream_register(pdev, ide);
> if (rc)
> goto err_tsm;
> -

Tidy up. I'd leave it.

> + /*
> + * Take a module reference so that we won't call unregister
> + * without rme_unasign_device
> + */
> + if (!try_module_get(THIS_MODULE)) {
> + rc = -ENXIO;
> + goto err_tsm;
> + }
> + rme_asign_device(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
> new file mode 100644
> index 000000000000..426e530ac182
> --- /dev/null
> +++ b/drivers/virt/coco/arm-cca-host/rmm-da.c
> @@ -0,0 +1,150 @@

> +
> +static int init_pdev_params(struct pci_dev *pdev, struct rmi_pdev_params *params)
> +{
> + void *aux;

Probably makes sense to reduce scope of aux to within the loop.

> + int rid, ret, i;
> + phys_addr_t aux_phys;
> + struct cca_host_dsc_pf0 *dsc_pf0;
> + struct pci_dev *rp = pcie_find_root_port(pdev);
Only used in one place for now anyway. Probably better
to move it down there.

> + struct pci_config_window *cfg = pdev->bus->sysdata;
> +
> + dsc_pf0 = to_cca_dsc_pf0(pdev);

I'd do that at declaration. Seems little advantage in doing it
down here.

> + /* assign the ep device with RMM */
> + rid = pci_dev_id(pdev);
> + params->pdev_id = rid;
> + /* slot number for certificate chain */
> + params->cert_id = 0;
> + /* io coherent spdm/ide and non p2p */
> + params->flags = RMI_PDEV_SPDM_TRUE | RMI_PDEV_IDE_TRUE;
> + params->ide_sid = dsc_pf0->sel_stream->stream_id;
> + params->hash_algo = RMI_HASH_SHA_256;
> + /* use the rid and MMIO resources of the epdev */

Spell out epdev or associate it with the pdev here more clearly.

> + params->rid_top = params->rid_base = rid;
> + params->ecam_addr = cfg->res.start;
> + params->root_id = pci_dev_id(rp);

params->root_id = pci_dev_id(pcie_find_root_port(pdev));
to me acts as better documentation fo what is going on than using
the local variable rp.

> +
> + params->ncoh_num_addr_range = pci_res_to_pdev_addr(params->ncoh_addr_range,
> + ARRAY_SIZE(params->ncoh_addr_range),
> + pdev->resource,
> + DEVICE_COUNT_RESOURCE);
> +
> + rmi_pdev_aux_count(params->flags, &params->num_aux);
> + pr_debug("%s using %ld pdev aux granules\n", __func__, (unsigned long)params->num_aux);
> + dsc_pf0->num_aux = params->num_aux;
> + for (i = 0; i < params->num_aux; i++) {

void *aux = (void *)__get_free_page(GFP_KERNEL);

> + aux = (void *)__get_free_page(GFP_KERNEL);
> + if (!aux) {
> + ret = -ENOMEM;
> + goto err_free_aux;
> + }
> +
> + aux_phys = virt_to_phys(aux);
> + if (rmi_granule_delegate(aux_phys)) {
> + ret = -ENXIO;
> + free_page((unsigned long)aux);
> + goto err_free_aux;
> + }
> + params->aux_granule[i] = aux_phys;
> + dsc_pf0->aux[i] = aux;
> + }
> + return 0;
> +
> +err_free_aux:
> + free_aux_pages(i, dsc_pf0->aux[i]);

I think you want
free_aux_pages(i, dsc_pf0->aux);
Assuming this is supposed to unwind the loop above.

> + return -ENOMEM;
> +}
> +
Trivial: Single line probably fine here.
> +
> +int rme_asign_device(struct pci_dev *pci_dev)
> +{
> + int ret;
> + void *rmm_pdev;
> + unsigned long state;
> + phys_addr_t rmm_pdev_phys;
> + struct rmi_pdev_params *params;
> + struct cca_host_dsc_pf0 *dsc_pf0;
> +
> + dsc_pf0 = to_cca_dsc_pf0(pci_dev);

Might as well save a line with

struct cca_host_dsc_pf0 *dsc_pf0 = to_cca_dsc_pf0(pci_dev);

> + rmm_pdev = (void *)get_zeroed_page(GFP_KERNEL);
> + if (!rmm_pdev) {
> + ret = -ENOMEM;

return -ENOMEM;

> + goto err_out;
> + }
> +
> + rmm_pdev_phys = virt_to_phys(rmm_pdev);
> + if (rmi_granule_delegate(rmm_pdev_phys)) {
> + ret = -ENXIO;
> + goto err_free_pdev;
> + }
> +
> + params = (struct rmi_pdev_params *)get_zeroed_page(GFP_KERNEL);
> + if (!params) {
> + ret = -ENOMEM;
> + goto err_granule_undelegate;
> + }
> +
> + ret = init_pdev_params(pci_dev, params);
> + if (ret)
> + goto err_free_params;
> +
> + ret = rmi_pdev_create(rmm_pdev_phys, virt_to_phys(params));
> + pr_info("rmi_pdev_create(0x%llx, 0x%llx): %d\n", rmm_pdev_phys, virt_to_phys(params), ret);

RFC, but even so I'd demote to debug and use dynamic debug stuff to enable
them for your testing.

> + if (ret)
> + goto err_free_aux;
> +
> + rmi_pdev_get_state(rmm_pdev_phys, &state);
> + if (state != RMI_PDEV_NEW)
> + goto err_free_aux;

Nothing to unwind in rmi_pdev_create()? We've told the
RMM about it then we blow away it's resources. Seems unwise!
Maybe this is cleaned up elsewhere but if so a comment is
probably good.

> +
> + dsc_pf0->rmm_pdev = rmm_pdev;
> + free_page((unsigned long)params);
> + return 0;
> +
> +err_free_aux:
> + free_aux_pages(dsc_pf0->num_aux, dsc_pf0->aux);
> +err_free_params:
> + free_page((unsigned long)params);
> +err_granule_undelegate:
> + rmi_granule_undelegate(rmm_pdev_phys);
> +err_free_pdev:
> + free_page((unsigned long)rmm_pdev);
> +err_out:

One of my favourite nitpicks. Why not just return if nothing to do?
That tends to save a reviewer a bit of scrolling when checking
error paths do correct unwinding.

> + return ret;
> +}
> diff --git a/drivers/virt/coco/arm-cca-host/rmm-da.h b/drivers/virt/coco/arm-cca-host/rmm-da.h
> index 840cb584acdd..179ba68f2430 100644
> --- a/drivers/virt/coco/arm-cca-host/rmm-da.h
> +++ b/drivers/virt/coco/arm-cca-host/rmm-da.h
> @@ -14,6 +14,10 @@
> struct cca_host_dsc_pf0 {
> struct pci_tsm_pf0 pci;
> struct pci_ide *sel_stream;
> +
> + void *rmm_pdev;
> + int num_aux;
> + void *aux[MAX_PDEV_AUX_GRANULES];
> };
>
> static inline struct cca_host_dsc_pf0 *to_cca_dsc_pf0(struct pci_dev *pdev)
> @@ -26,4 +30,5 @@ static inline struct cca_host_dsc_pf0 *to_cca_dsc_pf0(struct pci_dev *pdev)
> return container_of(tsm, struct cca_host_dsc_pf0, pci.tsm);
> }
>
> +int rme_asign_device(struct pci_dev *pdev);
> #endif