Commit fad133c7 authored by Tom Lendacky's avatar Tom Lendacky Committed by Borislav Petkov (AMD)
Browse files

crypto: ccp: Add the SNP_COMMIT command 



The SNP_COMMIT command is used to commit the currently installed version
of the SEV firmware. Once committed, the firmware cannot be replaced
with a previous firmware version (cannot be rolled back). This command
will also update the reported TCB to match that of the currently
installed firmware.

  [ mdr: Note the reported TCB update in the documentation/commit. ]

Signed-off-by: default avatarTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: default avatarMichael Roth <michael.roth@amd.com>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240126041126.1927228-25-michael.roth@amd.com
parent f5db8841

Documentation/virt/coco/sev-guest.rst

+11 −0
Original line number Diff line number Diff line
@@ -151,6 +151,17 @@ The SNP_PLATFORM_STATUS command is used to query the SNP platform status. The 
status includes API major, minor version and more. See the SEV-SNP

specification for further details.



2.5 SNP_COMMIT

--------------

:Technology: sev-snp

:Type: hypervisor ioctl cmd

:Returns (out): 0 on success, -negative on error



SNP_COMMIT is used to commit the currently installed firmware using the

SEV-SNP firmware SNP_COMMIT command. This prevents roll-back to a previously

committed firmware version. This will also update the reported TCB to match

that of the currently installed firmware.



3. SEV-SNP CPUID Enforcement

============================

drivers/crypto/ccp/sev-dev.c

+17 −0
Original line number Diff line number Diff line
@@ -222,6 +222,7 @@ static int sev_cmd_buffer_len(int cmd) 
	case SEV_CMD_SNP_PLATFORM_STATUS:	return sizeof(struct sev_data_snp_addr);

	case SEV_CMD_SNP_GUEST_REQUEST:		return sizeof(struct sev_data_snp_guest_request);

	case SEV_CMD_SNP_CONFIG:		return sizeof(struct sev_user_data_snp_config);

	case SEV_CMD_SNP_COMMIT:		return sizeof(struct sev_data_snp_commit);

	default:				return 0;

	}
@@ -1990,6 +1991,19 @@ static int sev_ioctl_do_snp_platform_status(struct sev_issue_cmd *argp) 
	return ret;

}



static int sev_ioctl_do_snp_commit(struct sev_issue_cmd *argp)

{

	struct sev_device *sev = psp_master->sev_data;

	struct sev_data_snp_commit buf;



	if (!sev->snp_initialized)

		return -EINVAL;



	buf.len = sizeof(buf);



	return __sev_do_cmd_locked(SEV_CMD_SNP_COMMIT, &buf, &argp->error);

}



static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg)

{

	void __user *argp = (void __user *)arg;
@@ -2044,6 +2058,9 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) 
	case SNP_PLATFORM_STATUS:

		ret = sev_ioctl_do_snp_platform_status(&input);

		break;

	case SNP_COMMIT:

		ret = sev_ioctl_do_snp_commit(&input);

		break;

	default:

		ret = -EINVAL;

		goto out;

include/linux/psp-sev.h

+9 −0
Original line number Diff line number Diff line
@@ -801,6 +801,15 @@ struct sev_platform_init_args { 
	bool probe;

};



/**

 * struct sev_data_snp_commit - SNP_COMMIT structure

 *

 * @len: length of the command buffer read by the PSP

 */

struct sev_data_snp_commit {

	u32 len;

} __packed;



#ifdef CONFIG_CRYPTO_DEV_SP_PSP



/**

include/uapi/linux/psp-sev.h

+1 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ enum { 
	SEV_GET_ID,	/* This command is deprecated, use SEV_GET_ID2 */

	SEV_GET_ID2,

	SNP_PLATFORM_STATUS,

	SNP_COMMIT,



	SEV_MAX,

};