linux-kernel - Re: [PATCH] crypto: ccp: Add a quirk to firmware update

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Date:   Tue, 9 Aug 2022 10:57:16 -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: Add a quirk to firmware update

On 8/7/22 19:15, Jarkko Sakkinen wrote:
> From: Jarkko Sakkinen <jarkko@...fian.com>

Looks good, just some minor commit message and comment changes requested.

> 
> A quirk for fixing the committed TCB version, when upgrading from earlier
> firmware version than 1.33.01. This is a known issue, and the documented

", when upgrading from earlier firmware version than 1.33.01" => "when 
upgrading from a firmware version earlier than 1.50"

> workaround is to load the firmware twice.
> 
> The issue realizes in a machine where the upgrade is done from firmware
> reporting having SEV API version 1.49, and requires the following
> workaround:

Replace the above paragraph with just: "Currently, this issue requires the 
following workaround:"

> 
> sudo modprobe -r kvm_amd
> sudo modprobe -r ccp
> sudo modprobe ccp
> sudo modprobe kvm_amd
> 
> Implement this workaround inside kernel by checking whether the API
> version is less than 1.50, and if so, download the firmware twice.
> This addresses the TCB version issue.
> 
> Link: https://lore.kernel.org/all/de02389f-249d-f565-1136-4af3655fab2a@profian.com/
> Reported-by: Harald Hoyer <harald@...fian.com>
> Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> ---
>   drivers/crypto/ccp/sev-dev.c | 16 ++++++++++++++--
>   1 file changed, 14 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 799b476fc3e8..8ae26c5c64f6 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -742,6 +742,11 @@ static int sev_update_firmware(struct device *dev)
>   	struct page *p;
>   	u64 data_size;
>   
> +	if (!sev_version_greater_or_equal(0, 15)) {
> +		dev_dbg(dev, "DOWNLOAD_FIRMWARE not supported\n");
> +		return -1;
> +	}
> +
>   	if (sev_get_firmware(dev, &firmware) == -ENOENT) {
>   		dev_dbg(dev, "No SEV firmware file present\n");
>   		return -1;
> @@ -774,6 +779,14 @@ static int sev_update_firmware(struct device *dev)
>   	data->len = firmware->size;
>   
>   	ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);
> +
> +	/*
> +	 * A quirk for fixing the committed TCB version, when upgrading from
> +	 * earlier firmware version than 1.33.01.

s/1.33.01/1.50/

Thanks,
Tom

> +	 */
> +	if (!ret && !sev_version_greater_or_equal(1, 50))
> +		ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);
> +
>   	if (ret)
>   		dev_dbg(dev, "Failed to update SEV firmware: %#x\n", error);
>   	else
> @@ -1283,8 +1296,7 @@ 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)
> +	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