[PATCH v5 2/9] KVM: SEV: Disable SEV on platform init failure

Pratik R. Sampat
2025-01-23T22:01:35Z

If the platform initialization sev_platform_init() fails, SEV cannot be
set up and a secure VM cannot be spawned. Therefore, in this case,
ensure that KVM does not set up, nor advertise support for SEV, SEV-ES,
and SEV-SNP.

Suggested-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Pratik R. Sampat <prsampat@amd.com>
---
v4..v5
* Export the failure of platform_init() to disable SEV+ support
---
---
arch/x86/kvm/svm/sev.c | 2 +-
drivers/crypto/ccp/sev-dev.c | 10 ++++++++++
include/linux/psp-sev.h | 3 +++
3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index b709c2f0945c..188f04247dcf 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2957,7 +2957,7 @@ void __init sev_hardware_setup(void)
bool sev_es_supported = false;
bool sev_supported = false;

- if (!sev_enabled || !npt_enabled || !nrips)
+ if (!is_sev_platform_init() || !sev_enabled || !npt_enabled || !nrips)
goto out;

/*
diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index b45cd60c19b0..374ca2dd5730 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -81,6 +81,8 @@ MODULE_FIRMWARE("amd/amd_sev_fam19h_model1xh.sbin"); /* 4th gen EPYC */
static bool psp_dead;
static int psp_timeout;

+static bool platform_init;
+
/* Trusted Memory Region (TMR):
* The TMR is a 1MB area that must be 1MB aligned. Use the page allocator
* to allocate the memory, which will return aligned memory for the specified
@@ -1358,6 +1360,12 @@ int sev_platform_init(struct sev_platform_init_args *args)
}
EXPORT_SYMBOL_GPL(sev_platform_init);

+bool is_sev_platform_init(void)
+{
+ return platform_init;
+}
+EXPORT_SYMBOL_GPL(is_sev_platform_init);
+
static int __sev_platform_shutdown_locked(int *error)
{
struct psp_device *psp = psp_master;
@@ -2427,6 +2435,8 @@ void sev_pci_init(void)
if (rc)
dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
args.error, rc);
+ else
+ platform_init = true;

dev_info(sev->dev, "SEV%s API:%d.%d build:%d\n", sev->snp_initialized ?
"-SNP" : "", sev->api_major, sev->api_minor, sev->build);
diff --git a/include/linux/psp-sev.h b/include/linux/psp-sev.h
index e841a8fbbb15..3a40b79fb37f 100644
--- a/include/linux/psp-sev.h
+++ b/include/linux/psp-sev.h
@@ -946,6 +946,7 @@ void *psp_copy_user_blob(u64 uaddr, u32 len);
void *snp_alloc_firmware_page(gfp_t mask);
void snp_free_firmware_page(void *addr);
bool snp_fw_valid(void);
+bool is_sev_platform_init(void);

#else /* !CONFIG_CRYPTO_DEV_SP_PSP */

@@ -982,6 +983,8 @@ static inline void snp_free_firmware_page(void *addr) { }

static inline bool snp_fw_valid(void) { return false; }

+static inline bool is_sev_platform_init(void) { return false; }
+
#endif /* CONFIG_CRYPTO_DEV_SP_PSP */

#endif /* __PSP_SEV_H__ */
--
2.43.0