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

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Message-ID: <20250730153220.00006866@huawei.com>
Date: Wed, 30 Jul 2025 15:32:20 +0100
From: Jonathan Cameron <Jonathan.Cameron@...wei.com>
To: "Aneesh Kumar K.V (Arm)" <aneesh.kumar@...nel.org>
CC: <linux-coco@...ts.linux.dev>, <kvmarm@...ts.linux.dev>,
	<linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <aik@....com>,
	<lukas@...ner.de>, Samuel Ortiz <sameo@...osinc.com>, Xu Yilun
	<yilun.xu@...ux.intel.com>, Jason Gunthorpe <jgg@...pe.ca>, "Suzuki K
 Poulose" <Suzuki.Poulose@....com>, Steven Price <steven.price@....com>,
	Catalin Marinas <catalin.marinas@....com>, Marc Zyngier <maz@...nel.org>,
	Will Deacon <will@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>
Subject: Re: [RFC PATCH v1 25/38] cca: guest: arm64: Realm device lock
 support

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

> Writing 1 to 'tsm/lock' will initiate the TDISP lock sequence.
> 
> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@...nel.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