mirror of
https://git.proxmox.com/git/qemu-server
synced 2025-10-31 21:26:53 +00:00
104 lines
2.7 KiB
C
104 lines
2.7 KiB
C
#include <stdio.h>
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#include <stdint.h>
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#include <stdbool.h>
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#include <sys/stat.h>
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#include <errno.h>
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#include <string.h>
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#define eprintf(...) fprintf(stderr, __VA_ARGS__)
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#define OUTPUT_DIR "/run/qemu-server"
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#define OUTPUT_FILENAME "host-hw-capabilities.json"
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#define OUTPUT_PATH OUTPUT_DIR "/" OUTPUT_FILENAME
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typedef struct {
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bool sev_support;
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bool sev_es_support;
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bool sev_snp_support;
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uint8_t cbitpos;
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uint8_t reduced_phys_bits;
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} cpu_caps_t;
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void query_cpu_capabilities(cpu_caps_t *res) {
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uint32_t eax, ebx, ecx, edx;
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// query Encrypted Memory Capabilities, see:
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// https://en.wikipedia.org/wiki/CPUID#EAX=8000001Fh:_Encrypted_Memory_Capabilities
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uint32_t query_function = 0x8000001F;
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asm volatile("cpuid"
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: "=a"(eax), "=b"(ebx), "=c"(ecx), "=d"(edx)
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: "0"(query_function)
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);
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res->sev_support = (eax & (1<<1)) != 0;
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res->sev_es_support = (eax & (1<<3)) != 0;
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res->sev_snp_support = (eax & (1<<4)) != 0;
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res->cbitpos = ebx & 0x3f;
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res->reduced_phys_bits = (ebx >> 6) & 0x3f;
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}
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int prepare_output_directory() {
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// Check that the directory exists and create it if it does not.
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struct stat statbuf;
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int ret = stat(OUTPUT_DIR, &statbuf);
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if (ret == 0) {
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if (!S_ISDIR(statbuf.st_mode)) {
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eprintf("Path '" OUTPUT_DIR "' already exists but is not a directory.\n");
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return 0;
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}
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} else if (errno == ENOENT) {
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if (mkdir(OUTPUT_DIR, 0755) != 0) {
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eprintf("Error creating directory '" OUTPUT_DIR "': %s\n", strerror(errno));
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return 0;
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}
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} else {
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eprintf("Error checking path '" OUTPUT_DIR "': %s\n", strerror(errno));
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return 0;
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}
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return 1;
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}
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int main() {
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if (!prepare_output_directory()) {
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return 1;
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}
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cpu_caps_t caps;
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query_cpu_capabilities(&caps);
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FILE *file = fopen(OUTPUT_PATH, "w");
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if (file == NULL) {
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eprintf("Error opening to file '" OUTPUT_PATH "': %s\n", strerror(errno));
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return 1;
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}
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int ret = fprintf(file,
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"{"
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" \"amd-sev\": {"
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" \"cbitpos\": %u,"
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" \"reduced-phys-bits\": %u,"
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" \"sev-support\": %s,"
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" \"sev-support-es\": %s,"
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" \"sev-support-snp\": %s"
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" }"
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" }\n",
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caps.cbitpos,
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caps.reduced_phys_bits,
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caps.sev_support ? "true" : "false",
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caps.sev_es_support ? "true" : "false",
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caps.sev_snp_support ? "true" : "false"
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);
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if (ret < 0) {
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eprintf("Error writing to file '" OUTPUT_PATH "': %s\n", strerror(errno));
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}
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ret = fclose(file);
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if (ret != 0) {
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eprintf("Error closing file '" OUTPUT_PATH "': %s\n", strerror(errno));
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}
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return 0;
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}
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