Re: [PATCH] crypto: ccp: Load the firmware twice when SEV API version < 1.43

[Tom Lendacky]

On 8/3/22 20:02, Jarkko Sakkinen wrote:
> From: Jarkko Sakkinen <jarkko@xxxxxxxxxxx>
>
> SEV-SNP does not initialize to a legit state, unless the firmware is
> loaded twice, when SEP API version < 1.43, and the firmware is updated
> to a later version. Because of this user space needs to work around
> this with "rmmod && modprobe" combo. Fix this by implementing the
> workaround to the driver.
>
> Reported-by: Harald Hoyer <harald@xxxxxxxxxxx>
> Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxxx>
> ---
>   drivers/crypto/ccp/sev-dev.c | 22 +++++++++++++++++++---
>   1 file changed, 19 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 799b476fc3e8..f2abb7439dde 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c

> @@ -1274,6 +1285,7 @@ void sev_pci_init(void)
>   {
>   	struct sev_device *sev = psp_master->sev_data;
>   	int error, rc;
> +	int i;
>   
>   	if (!sev)
>   		return;
> @@ -1283,9 +1295,13 @@ void sev_pci_init(void)
>   	if (sev_get_api_version())
>   		goto err;
>   
> -	if (sev_version_greater_or_equal(0, 15) &&
> -	    sev_update_firmware(sev->dev) == 0)
> -		sev_get_api_version();
> +	/*
> +	 * SEV-SNP does not work properly before loading the FW twice in the API
> +	 * versions older than SEV 1.43.
> +	 */
> +	for (i = 0; i < sev_version_greater_or_equal(0, 15) + sev_version_less(1, 43); i++)
> +		if (sev_update_firmware(sev->dev) == 0)
> +			sev_get_api_version();

I prefer to have this logic in the sev_update_firmware() function.

And while the loop is correct, it isn't obvious. Something in
sev_update_firmware() that just does:

	ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);

	if (!ret && sev_version_greater_or_equal(0, 15) && sev_version_less(1, 43))
		ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);

And place a comment before the second command that references the reason
for the second download.

Thanks,
Tom

>