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

From: Tom Lendacky
Date: Tue Aug 09 2022 - 11:57:39 EST


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

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@xxxxxxxxxxx/
Reported-by: Harald Hoyer <harald@xxxxxxxxxxx>
Signed-off-by: Jarkko Sakkinen <jarkko@xxxxxxxxxxx>
---
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