Re: [PATCH v4 5/5] crypto: ccp - Send PSP_CMD_TEE_RING_DESTROY when PSP_CMD_TEE_RING_INIT fails

[Shyam Sundar S K <Shyam-sundar.S-k@amd.com>]

On 1/6/2026 10:24, Mario Limonciello (AMD) wrote:
> The hibernate resume sequence involves loading a resume kernel that is just
> used for loading the hibernate image before shifting back to the existing
> kernel.
> 
> During that hibernate resume sequence the resume kernel may have loaded
> the ccp driver.  If this happens the resume kernel will also have called
> PSP_CMD_TEE_RING_INIT but it will never have called
> PSP_CMD_TEE_RING_DESTROY.
> 
> This is problematic because the existing kernel needs to re-initialize the
> ring.  One could argue that the existing kernel should call destroy
> as part of restore() but there is no guarantee that the resume kernel did
> or didn't load the ccp driver.  There is also no callback opportunity for
> the resume kernel to destroy before handing back control to the existing
> kernel.
> 
> Similar problems could potentially exist with the use of kdump and
> crash handling. I actually reproduced this issue like this:
> 
> 1) rmmod ccp
> 2) hibernate the system
> 3) resume the system
> 4) modprobe ccp
> 
> The resume kernel will have loaded ccp but never destroyed and then when
> I try to modprobe it fails.
> 
> Because of these possible cases add a flow that checks the error code from
> the PSP_CMD_TEE_RING_INIT call and tries to call PSP_CMD_TEE_RING_DESTROY
> if it failed.  If this succeeds then call PSP_CMD_TEE_RING_INIT again.
> 
> Fixes: f892a21f51162 ("crypto: ccp - use generic power management")
> Reported-by: Lars Francke <lars.francke@gmail.com>
> Closes: https://lore.kernel.org/platform-driver-x86/CAD-Ua_gfJnQSo8ucS_7ZwzuhoBRJ14zXP7s8b-zX3ZcxcyWePw@mail.gmail.com/
> Tested-by: Yijun Shen <Yijun.Shen@Dell.com>
> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
> ---
> v4:
>  * Add tag (Yijun)
>  * Move and rename PSP_TEE_STS_RING_BUSY (Ilpo)
> v3:
>  * Add a comment (Tom)
>  * Add a define for busy condition (Shyam)
>  * Rename label (Shyam)
>  * Upgrade message to info (Shyam)
>  * Use a helper that validates result for destroy command (Shyam)
> ---
>  drivers/crypto/ccp/tee-dev.c | 12 ++++++++++++
>  include/linux/psp.h          |  1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/tee-dev.c b/drivers/crypto/ccp/tee-dev.c
> index ef1430f86ad62..ea9b94d5b10ba 100644
> --- a/drivers/crypto/ccp/tee-dev.c
> +++ b/drivers/crypto/ccp/tee-dev.c
> @@ -113,6 +113,7 @@ static int tee_init_ring(struct psp_tee_device *tee)
>  {
>  	int ring_size = MAX_RING_BUFFER_ENTRIES * sizeof(struct tee_ring_cmd);
>  	struct tee_init_ring_cmd *cmd;
> +	bool retry = false;
>  	unsigned int reg;
>  	int ret;
>  
> @@ -135,6 +136,7 @@ static int tee_init_ring(struct psp_tee_device *tee)
>  	/* Send command buffer details to Trusted OS by writing to
>  	 * CPU-PSP message registers
>  	 */
> +retry_init:
>  	ret = psp_mailbox_command(tee->psp, PSP_CMD_TEE_RING_INIT, cmd,
>  				  TEE_DEFAULT_CMD_TIMEOUT, &reg);
>  	if (ret) {
> @@ -145,6 +147,16 @@ static int tee_init_ring(struct psp_tee_device *tee)
>  	}
>  
>  	if (FIELD_GET(PSP_CMDRESP_STS, reg)) {
> +		/*
> +		 * During the hibernate resume sequence driver may have gotten loaded
> +		 * but the ring not properly destroyed. If the ring doesn't work, try
> +		 * to destroy and re-init once.
> +		 */
> +		if (!retry && FIELD_GET(PSP_CMDRESP_STS, reg) == PSP_TEE_STS_RING_BUSY) {
> +			dev_info(tee->dev, "tee: ring init command failed with busy status, retrying\n");
> +			if (tee_send_destroy_cmd(tee))

so it becomes infinite retry? I think we need to set the retry flag to
true to indicate that ring busy.

> +				goto retry_init;
> +		}
>  		dev_err(tee->dev, "tee: ring init command failed (%#010lx)\n",
>  			FIELD_GET(PSP_CMDRESP_STS, reg));
>  		tee_free_ring(tee);
> diff --git a/include/linux/psp.h b/include/linux/psp.h
> index 92e60aeef21e1..b337dcce1e991 100644
> --- a/include/linux/psp.h
> +++ b/include/linux/psp.h
> @@ -18,6 +18,7 @@
>   * and should include an appropriate local definition in their source file.
>   */
>  #define PSP_CMDRESP_STS		GENMASK(15, 0)
> +#define  PSP_TEE_STS_RING_BUSY 0x0000000d  /* Ring already initialized */

additional spaces between the macro names.

Thanks,
Shyam

>  #define PSP_CMDRESP_CMD		GENMASK(23, 16)
>  #define PSP_CMDRESP_RESERVED	GENMASK(29, 24)
>  #define PSP_CMDRESP_RECOVERY	BIT(30)