Re: [RFC PATCH v1 25/38] cca: guest: arm64: Realm device lock support

Jonathan Cameron
2025-07-30T14:32:30Z

On Mon, 28 Jul 2025 19:22:02 +0530
"Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org> wrote:

> Writing 1 to 'tsm/lock' will initiate the TDISP lock sequence.
>
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
> ---
> arch/arm64/include/asm/rsi_cmds.h | 32 +++++++++++++-
> arch/arm64/include/asm/rsi_smc.h | 5 +++
> drivers/virt/coco/arm-cca-guest/Makefile | 2 +-
> drivers/virt/coco/arm-cca-guest/arm-cca.c | 18 ++++++++
> drivers/virt/coco/arm-cca-guest/rsi-da.c | 52 +++++++++++++++++++++++
> drivers/virt/coco/arm-cca-guest/rsi-da.h | 3 +-
> 6 files changed, 108 insertions(+), 4 deletions(-)
> create mode 100644 drivers/virt/coco/arm-cca-guest/rsi-da.c
>
> diff --git a/arch/arm64/include/asm/rsi_cmds.h b/arch/arm64/include/asm/rsi_cmds.h
> index d4834baeef1b..b9c4b8ff5631 100644
> --- a/arch/arm64/include/asm/rsi_cmds.h
> +++ b/arch/arm64/include/asm/rsi_cmds.h
> @@ -172,8 +172,36 @@ static inline int rsi_features(unsigned long index, unsigned long *out)
>
> arm_smccc_1_1_invoke(SMC_RSI_FEATURES, index, &res);
>
> - if (out)
> - *out = res.a1;
> + *out = res.a1;
> + return res.a0;

Seems unrelated change.

> +}
> +

> diff --git a/drivers/virt/coco/arm-cca-guest/rsi-da.c b/drivers/virt/coco/arm-cca-guest/rsi-da.c
> new file mode 100644
> index 000000000000..097cf52ee199
> --- /dev/null
> +++ b/drivers/virt/coco/arm-cca-guest/rsi-da.c
> @@ -0,0 +1,52 @@

> +int rsi_device_lock(struct pci_dev *pdev)
> +{
> + unsigned long ret;
> + struct cca_guest_dsc *dsm = to_cca_guest_dsc(pdev);
> + int vdev_id = (pci_domain_nr(pdev->bus) << 16) |
> + PCI_DEVID(pdev->bus->number, pdev->devfn);
> +
> + ret = rsi_rdev_get_instance_id(vdev_id, &dsm->instance_id);
> + if (ret != RSI_SUCCESS) {
> + pci_err(pdev, "failed to get the device instance id (%lu)\n", ret);
> + return -EIO;
> + }
> +
> + ret = rsi_rdev_lock(pdev, vdev_id, dsm->instance_id);
> + if (ret != RSI_SUCCESS) {
> + pci_err(pdev, "failed to lock the device (%lu)\n", ret);
> + return -EIO;
> + }
> +
> + return ret;
return 0?

You carefully overwrite other error codes. I assume RSI_SUCCESS == 0 but
even better to just return 0 directly in the good path.

> +}
> diff --git a/drivers/virt/coco/arm-cca-guest/rsi-da.h b/drivers/virt/coco/arm-cca-guest/rsi-da.h
> index 8a4d5f1b0263..f12430c7d792 100644
> --- a/drivers/virt/coco/arm-cca-guest/rsi-da.h
> +++ b/drivers/virt/coco/arm-cca-guest/rsi-da.h
> @@ -10,9 +10,9 @@
> #include <linux/pci-tsm.h>
> #include <asm/rsi_smc.h>
>
> -

Push back to earlier patch where I comment on this.

> struct cca_guest_dsc {
> struct pci_tsm_pf0 pci;
> + unsigned long instance_id;
> };
>
> static inline struct cca_guest_dsc *to_cca_guest_dsc(struct pci_dev *pdev)
> @@ -24,4 +24,5 @@ static inline struct cca_guest_dsc *to_cca_guest_dsc(struct pci_dev *pdev)
> return container_of(tsm, struct cca_guest_dsc, pci.tsm);
> }
>
> +int rsi_device_lock(struct pci_dev *pdev);
> #endif