[Qemu-devel] [PATCH v2 12/13] migration: add support to migrate page encryption bitmap

[Singh, Brijesh]

When memory encryption is enabled, the hypervisor maintains a page
encryption bitmap which is referred by hypervisor during migratoin to check
if page is private or shared. The bitmap is built during the VM bootup and
must be migrated to the target host so that hypervisor on target host can
use it for future migration. The KVM_{SET,GET}_PAGE_ENC_BITMAP can be used
to get and set the bitmap for a given gfn range.

Signed-off-by: Brijesh Singh <address@hidden>
---
 accel/kvm/kvm-all.c      |  4 +++
 migration/ram.c          | 11 +++++++
 target/i386/sev.c        | 67 ++++++++++++++++++++++++++++++++++++++++
 target/i386/trace-events |  2 ++
 4 files changed, 84 insertions(+)

diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 442b1af36e..9e23088a94 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1831,6 +1831,10 @@ static int kvm_init(MachineState *ms)
         kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
         kvm_state->memcrypt_save_outgoing_page = sev_save_outgoing_page;
         kvm_state->memcrypt_load_incoming_page = sev_load_incoming_page;
+        kvm_state->memcrypt_load_incoming_page_enc_bitmap =
+            sev_load_incoming_page_enc_bitmap;
+        kvm_state->memcrypt_save_outgoing_page_enc_bitmap =
+            sev_save_outgoing_page_enc_bitmap;
     }
 
     ret = kvm_arch_init(ms, s);
diff --git a/migration/ram.c b/migration/ram.c
index d179867e1b..3a4bdf3c03 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -78,6 +78,7 @@
 /* 0x80 is reserved in migration.h start with 0x100 next */
 #define RAM_SAVE_FLAG_COMPRESS_PAGE    0x100
 #define RAM_SAVE_FLAG_ENCRYPTED_PAGE   0x200
+#define RAM_SAVE_FLAG_PAGE_ENCRYPTED_BITMAP       0x400 /* used in 
target/i386/sev.c */
 
 static inline bool is_zero_range(uint8_t *p, uint64_t size)
 {
@@ -3595,6 +3596,10 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
     flush_compressed_data(rs);
     ram_control_after_iterate(f, RAM_CONTROL_FINISH);
 
+    if (kvm_memcrypt_enabled()) {
+        ret = kvm_memcrypt_save_outgoing_page_enc_bitmap(f);
+    }
+
     rcu_read_unlock();
 
     multifd_send_sync_main();
@@ -4469,6 +4474,12 @@ static int ram_load(QEMUFile *f, void *opaque, int 
version_id)
                     ret = -EINVAL;
             }
             break;
+        case RAM_SAVE_FLAG_PAGE_ENCRYPTED_BITMAP:
+            if (kvm_memcrypt_load_incoming_page_enc_bitmap(f)) {
+                error_report("Failed to load page enc bitmap");
+                ret = -EINVAL;
+            }
+            break;
         case RAM_SAVE_FLAG_EOS:
             /* normal exit */
             multifd_recv_sync_main();
diff --git a/target/i386/sev.c b/target/i386/sev.c
index 09a62d6f88..93c6a90806 100644
--- a/target/i386/sev.c
+++ b/target/i386/sev.c
@@ -63,6 +63,7 @@ static const char *const sev_fw_errlist[] = {
 };
 
 #define SEV_FW_MAX_ERROR      ARRAY_SIZE(sev_fw_errlist)
+#define RAM_SAVE_FLAG_PAGE_ENCRYPTED_BITMAP       0x400
 
 static int
 sev_ioctl(int fd, int cmd, void *data, int *error)
@@ -1189,6 +1190,72 @@ int sev_load_incoming_page(void *handle, QEMUFile *f, 
uint8_t *ptr)
     return sev_receive_update_data(f, ptr);
 }
 
+#define ALIGN(x, y)  (((x)+(y)-1) & ~((y)-1))
+
+int sev_load_incoming_page_enc_bitmap(void *handle, QEMUFile *f)
+{
+    void *bmap;
+    unsigned long npages;
+    unsigned long bmap_size, base_gpa;
+    struct kvm_page_enc_bitmap e = {};
+
+    base_gpa = qemu_get_be64(f);
+    npages = qemu_get_be64(f);
+    bmap_size = qemu_get_be64(f);
+
+    bmap = g_malloc0(bmap_size);
+    qemu_get_buffer(f, (uint8_t *)bmap, bmap_size);
+
+    trace_kvm_sev_load_page_enc_bitmap(base_gpa, npages << TARGET_PAGE_BITS);
+
+    e.start_gfn = base_gpa >> TARGET_PAGE_BITS;
+    e.num_pages = npages;
+    e.enc_bitmap = bmap;
+    if (kvm_vm_ioctl(kvm_state, KVM_SET_PAGE_ENC_BITMAP, &e) == -1) {
+        error_report("KVM_SET_PAGE_ENC_BITMAP ioctl failed %d", errno);
+        g_free(bmap);
+        return 1;
+    }
+
+    g_free(bmap);
+
+    return 0;
+}
+
+int sev_save_outgoing_page_enc_bitmap(void *handle, QEMUFile *f,
+                                      unsigned long start, uint64_t length)
+{
+    uint64_t size;
+    struct kvm_page_enc_bitmap e = {};
+
+    if (!length) {
+        return 0;
+    }
+
+    size = ALIGN((length >> TARGET_PAGE_BITS), /*HOST_LONG_BITS*/ 64) / 8;
+    e.enc_bitmap = g_malloc0(size);
+    e.start_gfn = start >> TARGET_PAGE_BITS;
+    e.num_pages = length >> TARGET_PAGE_BITS;
+
+    trace_kvm_sev_save_page_enc_bitmap(start, length);
+
+    if (kvm_vm_ioctl(kvm_state, KVM_GET_PAGE_ENC_BITMAP, &e) == -1) {
+        error_report("%s: KVM_GET_PAGE_ENC_BITMAP ioctl failed %d",
+                    __func__, errno);
+        g_free(e.enc_bitmap);
+        return 1;
+    }
+
+    qemu_put_be64(f, RAM_SAVE_FLAG_PAGE_ENCRYPTED_BITMAP);
+    qemu_put_be64(f, start);
+    qemu_put_be64(f, e.num_pages);
+    qemu_put_be64(f, size);
+    qemu_put_buffer(f, (uint8_t *)e.enc_bitmap, size);
+
+    g_free(e.enc_bitmap);
+    return 0;
+}
+
 static void
 sev_register_types(void)
 {
diff --git a/target/i386/trace-events b/target/i386/trace-events
index 609752cca7..4c2be570f9 100644
--- a/target/i386/trace-events
+++ b/target/i386/trace-events
@@ -21,3 +21,5 @@ kvm_sev_send_finish(void) ""
 kvm_sev_receive_start(int policy, void *session, void *pdh) "policy 0x%x 
session %p pdh %p"
 kvm_sev_receive_update_data(void *src, void *dst, int len, void *hdr, int 
hdr_len) "guest %p trans %p len %d hdr %p hdr_len %d"
 kvm_sev_receive_finish(void) ""
+kvm_sev_save_page_enc_bitmap(uint64_t start, uint64_t len) "start 0x%" PRIx64 
" len 0x%" PRIx64
+kvm_sev_load_page_enc_bitmap(uint64_t start, uint64_t len) "start 0x%" PRIx64 
" len 0x%" PRIx64
-- 
2.17.1