[RFC,v2,06/12] i386/sev: add support to encrypt BIOS when SEV-SNP is enabled

Commit Message

Michael Roth Aug. 26, 2021, 10:26 p.m. UTC

From: Brijesh Singh <[e-mail]>

The KVM_SEV_SNP_LAUNCH_UPDATE command is used for encrypting the bios
image used for booting the SEV-SNP guest.

Signed-off-by: Brijesh Singh <[e-mail]>
Signed-off-by: Michael Roth <[e-mail]>
---
 hw/i386/pc_sysfw.c       |  7 ++++---
 include/sysemu/sev.h     |  2 +-
 target/i386/sev-stub.c   |  2 +-
 target/i386/sev.c        | 40 ++++++++++++++++++++++++++++++++++++++--
 target/i386/trace-events |  1 +
 5 files changed, 45 insertions(+), 7 deletions(-)

Patch

diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
index 68d6b1f783..54ccf13c0e 100644
--- a/hw/i386/pc_sysfw.c
+++ b/hw/i386/pc_sysfw.c
@@ -149,6 +149,7 @@  static void pc_system_flash_map(PCMachineState *pcms,
     void *flash_ptr;
     int flash_size;
     int ret;
+    hwaddr gpa;
 
     assert(PC_MACHINE_GET_CLASS(pcms)->pci_enabled);
 
@@ -182,11 +183,11 @@  static void pc_system_flash_map(PCMachineState *pcms,
         }
 
         total_size += size;
+        gpa = 0x100000000ULL - total_size; /* where the flash is mapped */
         qdev_prop_set_uint32(DEVICE(system_flash), "num-blocks",
                              size / FLASH_SECTOR_SIZE);
         sysbus_realize_and_unref(SYS_BUS_DEVICE(system_flash), &error_fatal);
-        sysbus_mmio_map(SYS_BUS_DEVICE(system_flash), 0,
-                        0x100000000ULL - total_size);
+        sysbus_mmio_map(SYS_BUS_DEVICE(system_flash), 0, gpa);
 
         if (i == 0) {
             flash_mem = pflash_cfi01_get_memory(system_flash);
@@ -208,7 +209,7 @@  static void pc_system_flash_map(PCMachineState *pcms,
                     exit(1);
                 }
 
-                sev_encrypt_flash(flash_ptr, flash_size, &error_fatal);
+                sev_encrypt_flash(gpa, flash_ptr, flash_size, &error_fatal);
             }
         }
     }
diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
index 94d821d737..78e3bf97e8 100644
--- a/include/sysemu/sev.h
+++ b/include/sysemu/sev.h
@@ -18,7 +18,7 @@ 
 
 bool sev_enabled(void);
 int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp);
-int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp);
+int sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp);
 int sev_inject_launch_secret(const char *hdr, const char *secret,
                              uint64_t gpa, Error **errp);
 
diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
index e4fb8e882e..8b35704937 100644
--- a/target/i386/sev-stub.c
+++ b/target/i386/sev-stub.c
@@ -56,7 +56,7 @@  int sev_inject_launch_secret(const char *hdr, const char *secret,
     return 1;
 }
 
-int sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
+int sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp)
 {
     return 0;
 }
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 51689d4fa4..867c0cb457 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -946,6 +946,35 @@  out:
     return ret;
 }
 
+static int
+sev_snp_launch_update(SevSnpGuestState *sev_snp_guest, hwaddr gpa, uint8_t *addr,
+                      uint64_t len, int type)
+{
+    int ret, fw_error;
+    struct kvm_sev_snp_launch_update update = {0};
+
+    if (!addr || !len) {
+        error_report("%s: SNP_LAUNCH_UPDATE called with invalid address / length: %lx / %lx",
+                __func__, gpa, len);
+        return 1;
+    }
+
+    update.uaddr = (__u64)(unsigned long)addr;
+    update.start_gfn = gpa >> TARGET_PAGE_BITS;
+    update.len = len;
+    update.page_type = type;
+    trace_kvm_sev_snp_launch_update(addr, len, type);
+    ret = sev_ioctl(SEV_COMMON(sev_snp_guest)->sev_fd,
+                    KVM_SEV_SNP_LAUNCH_UPDATE,
+                    &update, &fw_error);
+    if (ret) {
+        error_report("%s: SNP_LAUNCH_UPDATE ret=%d fw_error=%d '%s'",
+                __func__, ret, fw_error, fw_error_to_str(fw_error));
+    }
+
+    return ret;
+}
+
 static int
 sev_launch_update_data(SevGuestState *sev_guest, uint8_t *addr, uint64_t len)
 {
@@ -1219,7 +1248,7 @@  err:
 }
 
 int
-sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
+sev_encrypt_flash(hwaddr gpa, uint8_t *ptr, uint64_t len, Error **errp)
 {
     SevCommonState *sev_common = SEV_COMMON(MACHINE(qdev_get_machine())->cgs);
 
@@ -1229,7 +1258,14 @@  sev_encrypt_flash(uint8_t *ptr, uint64_t len, Error **errp)
 
     /* if SEV is in update state then encrypt the data else do nothing */
     if (sev_check_state(sev_common, SEV_STATE_LAUNCH_UPDATE)) {
-        int ret = sev_launch_update_data(SEV_GUEST(sev_common), ptr, len);
+        int ret;
+
+        if (sev_snp_enabled()) {
+            ret = sev_snp_launch_update(SEV_SNP_GUEST(sev_common), gpa, ptr,
+                                        len, KVM_SEV_SNP_PAGE_TYPE_NORMAL);
+        } else {
+            ret = sev_launch_update_data(SEV_GUEST(sev_common), ptr, len);
+        }
         if (ret < 0) {
             error_setg(errp, "failed to encrypt pflash rom");
             return ret;
diff --git a/target/i386/trace-events b/target/i386/trace-events
index 18cc14b956..0c2d250206 100644
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -12,3 +12,4 @@  kvm_sev_launch_finish(void) ""
 kvm_sev_launch_secret(uint64_t hpa, uint64_t hva, uint64_t secret, int len) "hpa 0x%" PRIx64 " hva 0x%" PRIx64 " data 0x%" PRIx64 " len %d"
 kvm_sev_attestation_report(const char *mnonce, const char *data) "mnonce %s data %s"
 kvm_sev_snp_launch_start(uint64_t policy) "policy 0x%" PRIx64
+kvm_sev_snp_launch_update(void *addr, uint64_t len, int type) "addr %p len 0x%" PRIx64 " type %d"