[PATCH v2] crypto: ccp: Add a quirk to firmware update

[Jarkko Sakkinen <jarkko@kernel.org>]

From: Jarkko Sakkinen <jarkko@profian.com>

A quirk for fixing the committed TCB version, when upgrading from a
firmware version earlier than 1.50. This is a known issue, and the
documented workaround is to load the firmware twice.

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@profian.com>
Signed-off-by: Jarkko Sakkinen <jarkko@profian.com>
---
v2:
- Updated the commit message and comments.
  https://lore.kernel.org/all/0a3a790d-989f-2f76-f636-62fbd925a776@amd.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..f27f8bc966b1 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 1.50.
+	 */
+	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
-- 
2.37.1