Commit cb645fe4 authored by Brijesh Singh's avatar Brijesh Singh Committed by Borislav Petkov (AMD)
Browse files

crypto: ccp: Add the SNP_SET_CONFIG command 



The SEV-SNP firmware provides the SNP_CONFIG command used to set various
system-wide configuration values for SNP guests, such as the reported
TCB version used when signing guest attestation reports. Add an
interface to set this via userspace.

  [ mdr: Squash in doc patch from Dionna, drop extended request/
    certificate handling and simplify this to a simple wrapper around
    SNP_CONFIG fw cmd. ]

Signed-off-by: default avatarBrijesh Singh <brijesh.singh@amd.com>
Co-developed-by: default avatarAlexey Kardashevskiy <aik@amd.com>
Signed-off-by: default avatarAlexey Kardashevskiy <aik@amd.com>
Co-developed-by: default avatarDionna Glaze <dionnaglaze@google.com>
Signed-off-by: default avatarDionna Glaze <dionnaglaze@google.com>
Signed-off-by: default avatarAshish Kalra <ashish.kalra@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/20240126041126.1927228-26-michael.roth@amd.com
parent fad133c7

Documentation/virt/coco/sev-guest.rst

+13 −0
Original line number Diff line number Diff line
@@ -162,6 +162,19 @@ 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.



2.6 SNP_SET_CONFIG

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

:Technology: sev-snp

:Type: hypervisor ioctl cmd

:Parameters (in): struct sev_user_data_snp_config

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



SNP_SET_CONFIG is used to set the system-wide configuration such as

reported TCB version in the attestation report. The command is similar

to SNP_CONFIG command defined in the SEV-SNP spec. The current values of

the firmware parameters affected by this command can be queried via

SNP_PLATFORM_STATUS.



3. SEV-SNP CPUID Enforcement

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

drivers/crypto/ccp/sev-dev.c

+20 −0
Original line number Diff line number Diff line
@@ -2004,6 +2004,23 @@ static int sev_ioctl_do_snp_commit(struct sev_issue_cmd *argp) 
	return __sev_do_cmd_locked(SEV_CMD_SNP_COMMIT, &buf, &argp->error);

}



static int sev_ioctl_do_snp_set_config(struct sev_issue_cmd *argp, bool writable)

{

	struct sev_device *sev = psp_master->sev_data;

	struct sev_user_data_snp_config config;



	if (!sev->snp_initialized || !argp->data)

		return -EINVAL;



	if (!writable)

		return -EPERM;



	if (copy_from_user(&config, (void __user *)argp->data, sizeof(config)))

		return -EFAULT;



	return __sev_do_cmd_locked(SEV_CMD_SNP_CONFIG, &config, &argp->error);

}



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

{

	void __user *argp = (void __user *)arg;
@@ -2061,6 +2078,9 @@ static long sev_ioctl(struct file *file, unsigned int ioctl, unsigned long arg) 
	case SNP_COMMIT:

		ret = sev_ioctl_do_snp_commit(&input);

		break;

	case SNP_SET_CONFIG:

		ret = sev_ioctl_do_snp_set_config(&input, writable);

		break;

	default:

		ret = -EINVAL;

		goto out;

include/uapi/linux/psp-sev.h

+1 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ enum { 
	SEV_GET_ID2,

	SNP_PLATFORM_STATUS,

	SNP_COMMIT,

	SNP_SET_CONFIG,



	SEV_MAX,

};