Hello Tom,

On 2/20/2025 2:03 PM, Tom Lendacky wrote:

On 2/19/25 14:55, Ashish Kalra wrote:

quoted

From: Ashish Kalra <ashish.kalra@amd.com>

SNP initialization is forced during PSP driver probe purely because SNP
can't be initialized if VMs are running.  But the only in-tree user of
SEV/SNP functionality is KVM, and KVM depends on PSP driver for the same.
Forcing SEV/SNP initialization because a hypervisor could be running
legacy non-confidential VMs make no sense.

This patch removes SEV/SNP initialization from the PSP driver probe
time and moves the requirement to initialize SEV/SNP functionality
to KVM if it wants to use SEV/SNP.

Suggested-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Alexey Kardashevskiy <redacted>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
---
 drivers/crypto/ccp/sev-dev.c | 25 +------------------------
 1 file changed, 1 insertion(+), 24 deletions(-)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index f0f3e6d29200..99a663dbc2b6 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c

@@ -1346,18 +1346,13 @@ static int _sev_platform_init_locked(struct sev_platform_init_args *args)
 	if (sev->state == SEV_STATE_INIT)
 		return 0;
 
-	/*
-	 * Legacy guests cannot be running while SNP_INIT(_EX) is executing,
-	 * so perform SEV-SNP initialization at probe time.
-	 */
 	rc = __sev_snp_init_locked(&args->error);
 	if (rc && rc != -ENODEV) {
 		/*
 		 * Don't abort the probe if SNP INIT failed,
 		 * continue to initialize the legacy SEV firmware.
 		 */
-		dev_err(sev->dev, "SEV-SNP: failed to INIT rc %d, error %#x\n",
-			rc, args->error);
+		dev_err(sev->dev, "SEV-SNP: failed to INIT, continue SEV INIT\n");

Please don't remove the error information.

The error(s) are already being printed in __sev_snp_init_locked() otherwise the same
error will be printed twice, hence removing it here.

quoted

 	}
 
 	/* Defer legacy SEV/SEV-ES support if allowed by caller/module. */

@@ -2505,9 +2500,7 @@ EXPORT_SYMBOL_GPL(sev_issue_cmd_external_user);
 void sev_pci_init(void)
 {
 	struct sev_device *sev = psp_master->sev_data;
-	struct sev_platform_init_args args = {0};
 	u8 api_major, api_minor, build;
-	int rc;
 
 	if (!sev)
 		return;

@@ -2530,16 +2523,6 @@ void sev_pci_init(void)
 			 api_major, api_minor, build,
 			 sev->api_major, sev->api_minor, sev->build);
 
-	/* Initialize the platform */
-	args.probe = true;
-	rc = sev_platform_init(&args);
-	if (rc)
-		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
-			args.error, rc);
-
-	dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
-		"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
-
 	return;
 
 err:

@@ -2550,10 +2533,4 @@ void sev_pci_init(void)
 
 void sev_pci_exit(void)
 {
-	struct sev_device *sev = psp_master->sev_data;
-
-	if (!sev)
-		return;
-
-	sev_firmware_shutdown(sev);

Should this remain? If there's a bug in KVM that somehow skips the
shutdown call, then SEV will remain initialized. I think the path is
safe to call a second time.

Ok.

Thanks,
Ashish