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SubjectRe: [RFC PATCH v3 4/6] crypto: ccp - check whether PSP supports SEV or TEE before initialization
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On 12/4/19 12:19 AM, Rijo Thomas wrote:
> Read PSP feature register to check for TEE (Trusted Execution Environment)
> support.
>
> If neither SEV nor TEE is supported by PSP, then skip PSP initialization.
>
> Cc: Tom Lendacky <thomas.lendacky@amd.com>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Co-developed-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
> Signed-off-by: Devaraj Rangasamy <Devaraj.Rangasamy@amd.com>
> Signed-off-by: Rijo Thomas <Rijo-john.Thomas@amd.com>

Acked-by: Gary R Hook <gary.hook@amd.com>

> ---
> drivers/crypto/ccp/psp-dev.c | 46 +++++++++++++++++++++++++++++++++++++++-----
> 1 file changed, 41 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> index 2cd7a5e..3bedf72 100644
> --- a/drivers/crypto/ccp/psp-dev.c
> +++ b/drivers/crypto/ccp/psp-dev.c
> @@ -53,7 +53,7 @@ static irqreturn_t psp_irq_handler(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> -static int psp_check_sev_support(struct psp_device *psp)
> +static unsigned int psp_get_capability(struct psp_device *psp)
> {
> unsigned int val = ioread32(psp->io_regs + psp->vdata->feature_reg);
>
> @@ -66,11 +66,17 @@ static int psp_check_sev_support(struct psp_device *psp)
> */
> if (val == 0xffffffff) {
> dev_notice(psp->dev, "psp: unable to access the device: you might be running a broken BIOS.\n");
> - return -ENODEV;
> + return 0;
> }
>
> - if (!(val & 1)) {
> - /* Device does not support the SEV feature */
> + return val;
> +}
> +
> +static int psp_check_sev_support(struct psp_device *psp,
> + unsigned int capability)
> +{
> + /* Check if device supports SEV feature */
> + if (!(capability & 1)) {
> dev_dbg(psp->dev, "psp does not support SEV\n");
> return -ENODEV;
> }
> @@ -78,10 +84,36 @@ static int psp_check_sev_support(struct psp_device *psp)
> return 0;
> }
>
> +static int psp_check_tee_support(struct psp_device *psp,
> + unsigned int capability)
> +{
> + /* Check if device supports TEE feature */
> + if (!(capability & 2)) {
> + dev_dbg(psp->dev, "psp does not support TEE\n");
> + return -ENODEV;
> + }
> +
> + return 0;
> +}
> +
> +static int psp_check_support(struct psp_device *psp,
> + unsigned int capability)
> +{
> + int sev_support = psp_check_sev_support(psp, capability);
> + int tee_support = psp_check_tee_support(psp, capability);
> +
> + /* Return error if device neither supports SEV nor TEE */
> + if (sev_support && tee_support)
> + return -ENODEV;
> +
> + return 0;
> +}
> +
> int psp_dev_init(struct sp_device *sp)
> {
> struct device *dev = sp->dev;
> struct psp_device *psp;
> + unsigned int capability;
> int ret;
>
> ret = -ENOMEM;
> @@ -100,7 +132,11 @@ int psp_dev_init(struct sp_device *sp)
>
> psp->io_regs = sp->io_map;
>
> - ret = psp_check_sev_support(psp);
> + capability = psp_get_capability(psp);
> + if (!capability)
> + goto e_disable;
> +
> + ret = psp_check_support(psp, capability);
> if (ret)
> goto e_disable;
>
>

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