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/* SPDX-License-Identifier: LGPL-2.1-or-later */
#if defined(__i386__) || defined(__x86_64__)
#include <cpuid.h>
#endif
#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include "confidential-virt-fundamental.h"
#include "confidential-virt.h"
#include "fd-util.h"
#include "missing_threads.h"
#include "string-table.h"
#include "utf8.h"
#if defined(__x86_64__)
static void cpuid(uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx) {
log_debug("CPUID func %" PRIx32 " %" PRIx32, *eax, *ecx);
__cpuid_count(*eax, *ecx, *eax, *ebx, *ecx, *edx);
log_debug("CPUID result %" PRIx32 " %" PRIx32 " %" PRIx32 " %" PRIx32, *eax, *ebx, *ecx, *edx);
}
static uint32_t cpuid_leaf(uint32_t eax, char ret_sig[static 13], bool swapped) {
/* zero-init as some queries explicitly require subleaf == 0 */
uint32_t sig[3] = {};
if (swapped)
cpuid(&eax, &sig[0], &sig[2], &sig[1]);
else
cpuid(&eax, &sig[0], &sig[1], &sig[2]);
memcpy(ret_sig, sig, sizeof(sig));
ret_sig[12] = 0; /* \0-terminate the string to make string comparison possible */
/* In some CI tests ret_sig doesn't contain valid UTF8 and prints garbage to the console */
log_debug("CPUID sig '%s'", strna(utf8_is_valid(ret_sig)));
return eax;
}
#define MSR_DEVICE "/dev/cpu/0/msr"
static uint64_t msr(uint64_t index) {
uint64_t ret;
ssize_t rv;
_cleanup_close_ int fd = -EBADF;
fd = open(MSR_DEVICE, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
log_debug_errno(errno,
"Cannot open MSR device %s (index %" PRIu64 "), ignoring: %m",
MSR_DEVICE,
index);
return 0;
}
rv = pread(fd, &ret, sizeof(ret), index);
if (rv < 0) {
log_debug_errno(errno,
"Cannot read MSR device %s (index %" PRIu64 "), ignoring: %m",
MSR_DEVICE,
index);
return 0;
} else if (rv != sizeof(ret)) {
log_debug("Short read %zd bytes from MSR device %s (index %" PRIu64 "), ignoring",
rv,
MSR_DEVICE,
index);
return 0;
}
log_debug("MSR %" PRIu64 " result %" PRIu64 "", index, ret);
return ret;
}
static bool detect_hyperv_sev(void) {
uint32_t eax, ebx, ecx, edx, feat;
char sig[13] = {};
feat = cpuid_leaf(CPUID_HYPERV_VENDOR_AND_MAX_FUNCTIONS, sig, false);
if (feat < CPUID_HYPERV_MIN || feat > CPUID_HYPERV_MAX)
return false;
if (memcmp(sig, CPUID_SIG_HYPERV, sizeof(sig)) != 0)
return false;
log_debug("CPUID is on hyperv");
eax = CPUID_HYPERV_FEATURES;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
if (ebx & CPUID_HYPERV_ISOLATION && !(ebx & CPUID_HYPERV_CPU_MANAGEMENT)) {
eax = CPUID_HYPERV_ISOLATION_CONFIG;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
if ((ebx & CPUID_HYPERV_ISOLATION_TYPE_MASK) == CPUID_HYPERV_ISOLATION_TYPE_SNP)
return true;
}
return false;
}
static ConfidentialVirtualization detect_sev(void) {
uint32_t eax, ebx, ecx, edx;
uint64_t msrval;
eax = CPUID_GET_HIGHEST_FUNCTION;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
if (eax < CPUID_AMD_GET_ENCRYPTED_MEMORY_CAPABILITIES)
return CONFIDENTIAL_VIRTUALIZATION_NONE;
eax = CPUID_AMD_GET_ENCRYPTED_MEMORY_CAPABILITIES;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
/* bit 1 == CPU supports SEV feature
*
* Note, Azure blocks this CPUID leaf from its SEV-SNP
* guests, so we must fallback to trying some HyperV
* specific CPUID checks.
*/
if (!(eax & EAX_SEV)) {
log_debug("No sev in CPUID, trying hyperv CPUID");
if (detect_hyperv_sev())
return CONFIDENTIAL_VIRTUALIZATION_SEV_SNP;
log_debug("No hyperv CPUID");
return CONFIDENTIAL_VIRTUALIZATION_NONE;
}
msrval = msr(MSR_AMD64_SEV);
/* Test reverse order, since the SEV-SNP bit implies
* the SEV-ES bit, which implies the SEV bit */
if (msrval & MSR_SEV_SNP)
return CONFIDENTIAL_VIRTUALIZATION_SEV_SNP;
if (msrval & MSR_SEV_ES)
return CONFIDENTIAL_VIRTUALIZATION_SEV_ES;
if (msrval & MSR_SEV)
return CONFIDENTIAL_VIRTUALIZATION_SEV;
return CONFIDENTIAL_VIRTUALIZATION_NONE;
}
static ConfidentialVirtualization detect_tdx(void) {
uint32_t eax, ebx, ecx, edx;
char sig[13] = {};
eax = CPUID_GET_HIGHEST_FUNCTION;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
if (eax < CPUID_INTEL_TDX_ENUMERATION)
return CONFIDENTIAL_VIRTUALIZATION_NONE;
cpuid_leaf(CPUID_INTEL_TDX_ENUMERATION, sig, true);
if (memcmp(sig, CPUID_SIG_INTEL_TDX, sizeof(sig)) == 0)
return CONFIDENTIAL_VIRTUALIZATION_TDX;
return CONFIDENTIAL_VIRTUALIZATION_NONE;
}
static bool detect_hypervisor(void) {
uint32_t eax, ebx, ecx, edx;
bool is_hv;
eax = CPUID_PROCESSOR_INFO_AND_FEATURE_BITS;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
is_hv = ecx & CPUID_FEATURE_HYPERVISOR;
log_debug("CPUID is hypervisor: %s", yes_no(is_hv));
return is_hv;
}
ConfidentialVirtualization detect_confidential_virtualization(void) {
static thread_local ConfidentialVirtualization cached_found = _CONFIDENTIAL_VIRTUALIZATION_INVALID;
char sig[13] = {};
ConfidentialVirtualization cv = CONFIDENTIAL_VIRTUALIZATION_NONE;
if (cached_found >= 0)
return cached_found;
/* Skip everything on bare metal */
if (detect_hypervisor()) {
cpuid_leaf(0, sig, true);
if (memcmp(sig, CPUID_SIG_AMD, sizeof(sig)) == 0)
cv = detect_sev();
else if (memcmp(sig, CPUID_SIG_INTEL, sizeof(sig)) == 0)
cv = detect_tdx();
}
cached_found = cv;
return cv;
}
#else /* ! x86_64 */
ConfidentialVirtualization detect_confidential_virtualization(void) {
log_debug("No confidential virtualization detection on this architecture");
return CONFIDENTIAL_VIRTUALIZATION_NONE;
}
#endif /* ! x86_64 */
static const char *const confidential_virtualization_table[_CONFIDENTIAL_VIRTUALIZATION_MAX] = {
[CONFIDENTIAL_VIRTUALIZATION_NONE] = "none",
[CONFIDENTIAL_VIRTUALIZATION_SEV] = "sev",
[CONFIDENTIAL_VIRTUALIZATION_SEV_ES] = "sev-es",
[CONFIDENTIAL_VIRTUALIZATION_SEV_SNP] = "sev-snp",
[CONFIDENTIAL_VIRTUALIZATION_TDX] = "tdx",
};
DEFINE_STRING_TABLE_LOOKUP(confidential_virtualization, ConfidentialVirtualization);
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