[PATCH 1/2] crypto: ccp - simplify sev_update_firmware()

[Tycho Andersen <tycho@kernel.org>]

From: "Tycho Andersen (AMD)" <tycho@kernel.org>

sev_do_cmd() has its own command buffer (sev->cmd_buf) with the correct
alignment, perms, etc. that it copies the command into, so prepending it to
the firmware data is unnecessary.

Switch sev_update_firmware() to using a stack allocated command in light of
this copy, and drop all of the resulting pointer math.

Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
---
 drivers/crypto/ccp/sev-dev.c | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 096f993974d1..c45c74190c75 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -1967,11 +1967,11 @@ static int sev_get_firmware(struct device *dev,
 /* Don't fail if SEV FW couldn't be updated. Continue with existing SEV FW */
 static int sev_update_firmware(struct device *dev)
 {
-	struct sev_data_download_firmware *data;
+	struct sev_data_download_firmware data;
 	const struct firmware *firmware;
 	int ret, error, order;
 	struct page *p;
-	u64 data_size;
+	void *fw_blob;
 
 	if (!sev_version_greater_or_equal(0, 15)) {
 		dev_dbg(dev, "DOWNLOAD_FIRMWARE not supported\n");
@@ -1983,16 +1983,7 @@ static int sev_update_firmware(struct device *dev)
 		return -1;
 	}
 
-	/*
-	 * SEV FW expects the physical address given to it to be 32
-	 * byte aligned. Memory allocated has structure placed at the
-	 * beginning followed by the firmware being passed to the SEV
-	 * FW. Allocate enough memory for data structure + alignment
-	 * padding + SEV FW.
-	 */
-	data_size = ALIGN(sizeof(struct sev_data_download_firmware), 32);
-
-	order = get_order(firmware->size + data_size);
+	order = get_order(firmware->size);
 	p = alloc_pages(GFP_KERNEL, order);
 	if (!p) {
 		ret = -1;
@@ -2003,20 +1994,20 @@ static int sev_update_firmware(struct device *dev)
 	 * Copy firmware data to a kernel allocated contiguous
 	 * memory region.
 	 */
-	data = page_address(p);
-	memcpy(page_address(p) + data_size, firmware->data, firmware->size);
+	fw_blob = page_address(p);
+	memcpy(fw_blob, firmware->data, firmware->size);
 
-	data->address = __psp_pa(page_address(p) + data_size);
-	data->len = firmware->size;
+	data.address = __psp_pa(fw_blob);
+	data.len = firmware->size;
 
-	ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, data, &error);
+	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);
+		ret = sev_do_cmd(SEV_CMD_DOWNLOAD_FIRMWARE, &data, &error);
 
 	if (ret)
 		dev_dbg(dev, "Failed to update SEV firmware: %#x\n", error);

base-commit: 11439c4635edd669ae435eec308f4ab8a0804808
-- 
2.53.0