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

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Message-ID: <20250123220100.339867-3-prsampat@amd.com>
Date: Thu, 23 Jan 2025 16:00:53 -0600
From: "Pratik R. Sampat" <prsampat@....com>
To: <linux-kernel@...r.kernel.org>, <x86@...nel.org>, <kvm@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>, <linux-kselftest@...r.kernel.org>
CC: <seanjc@...gle.com>, <pbonzini@...hat.com>, <thomas.lendacky@....com>,
	<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>,
	<dave.hansen@...ux.intel.com>, <shuah@...nel.org>, <pgonda@...gle.com>,
	<ashish.kalra@....com>, <nikunj@....com>, <michael.roth@....com>,
	<sraithal@....com>, <prsampat@....com>
Subject: [PATCH v5 2/9] KVM: SEV: Disable SEV on platform init failure

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@....com>
Signed-off-by: Pratik R. Sampat <prsampat@....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