crypto: ccp - Flush the SEV-ES TMR memory before giving it to firmware

[ Upstream commit 46a334a98f ]

Perform a cache flush on the SEV-ES TMR memory after allocation to prevent
any possibility of the firmware encountering an error should dirty cache
lines be present. Use clflush_cache_range() to flush the SEV-ES TMR memory.

Fixes: 97f9ac3db6 ("crypto: ccp - Add support for SEV-ES to the PSP driver")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/crypto/ccp/sev-dev.c

@@ -23,6 +23,7 @@
 #include <linux/gfp.h>
 
 #include <asm/smp.h>
+#include <asm/cacheflush.h>
 
 #include "psp-dev.h"
 #include "sev-dev.h"
@@ -1067,7 +1068,10 @@ void sev_pci_init(void)
 
 	/* Obtain the TMR memory area for SEV-ES use */
 	sev_es_tmr = sev_fw_alloc(SEV_ES_TMR_SIZE);
-	if (!sev_es_tmr)
+	if (sev_es_tmr)
+		/* Must flush the cache before giving it to the firmware */
+		clflush_cache_range(sev_es_tmr, SEV_ES_TMR_SIZE);
+	else
 		dev_warn(sev->dev,
 			 "SEV: TMR allocation failed, SEV-ES support unavailable\n");