@@ -409,4 +409,10 @@ int sgx_virt_einit(void __user *sigstruct, void __user *token,
int sgx_set_attribute(unsigned long *allowed_attributes,
unsigned int attribute_fd);
+#ifdef CONFIG_X86_SGX
+extern void sgx_update_cpusvn_intel(void);
+#else
+static inline void sgx_update_cpusvn_intel(void) {}
+#endif
+
#endif /* _ASM_X86_SGX_H */
@@ -59,6 +59,7 @@
#include <asm/cpu_device_id.h>
#include <asm/uv/uv.h>
#include <asm/sigframe.h>
+#include <asm/sgx.h>
#include <asm/traps.h>
#include "cpu.h"
@@ -2224,6 +2225,15 @@ void microcode_check(void)
perf_check_microcode();
+ /*
+ * SGX attestation incorporates the microcode versions of all processors
+ * on the system and is affected by microcode updates. So, update SGX
+ * attestation metric (called CPUSVN) to ensure enclaves attest to the
+ * new version after microcode update.
+ */
+ if (IS_ENABLED(CONFIG_X86_SGX) && (cpuid_eax(SGX_CPUID) & SGX_CPUID_EUPDATESVN))
+ sgx_update_cpusvn_intel();
+
/* Reload CPUID max function as it might've changed. */
info.cpuid_level = cpuid_eax(0);
@@ -1403,3 +1403,15 @@ static int sgx_updatesvn(void)
return ret;
}
+
+void sgx_update_cpusvn_intel(void)
+{
+ sgx_lock_epc();
+ if (sgx_zap_pages())
+ goto out;
+
+ sgx_updatesvn();
+
+out:
+ sgx_unlock_epc();
+}
EUPDATESVN is the SGX instruction which allows enclave attestation to include information about updated microcode without a reboot. Microcode updates which affect SGX require two phases: 1. Do the main microcode update 2. Make the new CPUSVN available for enclave attestation via EUPDATESVN. Before a EUPDATESVN can succeed, all enclave pages (EPC) must be marked as unused in the SGX metadata (EPCM). This operation destroys all preexisting SGX enclave data and metadata. This is by design and mitigates the impact of vulnerabilities that may have compromised enclaves or the SGX hardware itself prior to the update. Signed-off-by: Cathy Zhang <cathy.zhang@intel.com> --- Changes since v4: - Remove #include <asm/sgx.h> from microcode.h which is not needed in this file. (Borislav Petkov) Changes since v3: - Rename update_cpusvn_intel() as sgx_update_cpusvn_intel(). (Dave Hansen) - Refine the comments when sgx_update_cpusvn_intel is called by microcode_check(). (Borislav Petkov, Dave Hansen) - Define both the 'static inline' stub *and* the declaration for sgx_update_cpusvn_intel() in sgx.h. (Dave Hansen) Changes since v1: - Remove the sysfs file svnupdate. (Thomas Gleixner, Dave Hansen) - Let late microcode load path call ENCLS[EUPDATESVN] procedure directly. (Borislav Petkov) - Redefine update_cpusvn_intel() to return void instead of int. --- arch/x86/include/asm/sgx.h | 6 ++++++ arch/x86/kernel/cpu/common.c | 10 ++++++++++ arch/x86/kernel/cpu/sgx/main.c | 12 ++++++++++++ 3 files changed, 28 insertions(+)