linux-kernel - Re: [PATCH] crypto: ccp: Load the firmware twice when SEV API version

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Message-ID: <58e8f9dc-a8d3-a2a5-2dd7-0783355e2567@amd.com>
Date:   Thu, 4 Aug 2022 08:13:35 -0500
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Jarkko Sakkinen <jarkko@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     Jarkko Sakkinen <jarkko@...fian.com>,
        Harald Hoyer <harald@...fian.com>,
        Brijesh Singh <brijesh.singh@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        "open list:AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER - SE..." 
        <linux-crypto@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] crypto: ccp: Load the firmware twice when SEV API version
 < 1.43

On 8/3/22 20:02, Jarkko Sakkinen wrote:
> From: Jarkko Sakkinen <jarkko@...fian.com>
> 
> 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.

The SNP hypervisor patches are placing a minimum supported version
requirement for the SEV firmware that exceeds the specified version
above [1] (for the reason above, as well as some others), so this patch
is not needed, NAK.

[1] https://lore.kernel.org/lkml/87a0481526e66ddd5f6192cbb43a50708aee2883.1655761627.git.ashish.kalra@amd.com/

Thanks,
Tom

> 
> Reported-by: Harald Hoyer <harald@...fian.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> ---
>   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
> @@ -76,6 +76,9 @@ static void *sev_es_tmr;
>   #define NV_LENGTH (32 * 1024)
>   static void *sev_init_ex_buffer;
>   
> +/*
> + * SEV API version >= maj.min?
> + */
>   static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
>   {
>   	struct sev_device *sev = psp_master->sev_data;
> @@ -89,6 +92,14 @@ static inline bool sev_version_greater_or_equal(u8 maj, u8 min)
>   	return false;
>   }
>   
> +/*
> + * SEV API version < maj.min?
> + */
> +static inline bool sev_version_less(u8 maj, u8 min)
> +{
> +	return !sev_version_greater_or_equal(maj, min);
> +}
> +
>   static void sev_irq_handler(int irq, void *data, unsigned int status)
>   {
>   	struct sev_device *sev = data;
> @@ -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();
>   
>   	/* If an init_ex_path is provided rely on INIT_EX for PSP initialization
>   	 * instead of INIT.