* Singh, Brijesh (brijesh.si...@amd.com) wrote:
> When memory encryption is enabled, the guest memory will be encrypted with
> the guest specific key. The patch introduces RAM_SAVE_FLAG_ENCRYPTED_PAGE
> flag to distinguish the encrypted data from plaintext. Encrypted pages
> may need special handling. The kvm_memcrypt_save_outgoing_page() is used
> by the sender to write the encrypted pages onto the socket, similarly the
> kvm_memcrypt_load_incoming_page() is used by the target to read the
> encrypted pages from the socket and load into the guest memory.
>
> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
Reviewed-by: Dr. David Alan Gilbert <dgilb...@redhat.com>
> ---
> migration/ram.c | 131 +++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 130 insertions(+), 1 deletion(-)
>
> diff --git a/migration/ram.c b/migration/ram.c
> index 57c707525b..100a5a10cd 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -59,6 +59,9 @@
> #include "qemu/iov.h"
> #include "hw/boards.h"
>
> +/* Defines RAM_SAVE_ENCRYPTED_PAGE and RAM_SAVE_ENCRYPTED_BITMAP */
> +#include "sysemu/sev.h"
> +
> /***********************************************************/
> /* ram save/restore */
>
> @@ -77,6 +80,7 @@
> #define RAM_SAVE_FLAG_XBZRLE 0x40
> /* 0x80 is reserved in migration.h start with 0x100 next */
> #define RAM_SAVE_FLAG_COMPRESS_PAGE 0x100
> +#define RAM_SAVE_FLAG_ENCRYPTED_DATA 0x200
>
> static inline bool is_zero_range(uint8_t *p, uint64_t size)
> {
> @@ -460,6 +464,9 @@ static QemuCond decomp_done_cond;
>
> static bool do_compress_ram_page(QEMUFile *f, z_stream *stream, RAMBlock
> *block,
> ram_addr_t offset, uint8_t *source_buf);
> +static int ram_save_encrypted_page(RAMState *rs, PageSearchStatus *pss,
> + bool last_stage);
> +
>
> static void *do_data_compress(void *opaque)
> {
> @@ -2039,6 +2046,73 @@ static int save_normal_page(RAMState *rs, RAMBlock
> *block, ram_addr_t offset,
> return 1;
> }
>
> +/**
> + * ram_save_encrypted_page - send the given encrypted page to the stream
> + */
> +static int ram_save_encrypted_page(RAMState *rs, PageSearchStatus *pss,
> + bool last_stage)
> +{
> + int ret;
> + uint8_t *p;
> + RAMBlock *block = pss->block;
> + ram_addr_t offset = pss->page << TARGET_PAGE_BITS;
> + uint64_t bytes_xmit;
> + MachineState *ms = MACHINE(qdev_get_machine());
> + MachineClass *mc = MACHINE_GET_CLASS(ms);
> + struct MachineMemoryEncryptionOps *ops = mc->memory_encryption_ops;
> +
> + p = block->host + offset;
> +
> + ram_counters.transferred +=
> + save_page_header(rs, rs->f, block,
> + offset | RAM_SAVE_FLAG_ENCRYPTED_DATA);
> +
> + qemu_put_be32(rs->f, RAM_SAVE_ENCRYPTED_PAGE);
> + ret = ops->save_outgoing_page(rs->f, p, TARGET_PAGE_SIZE, &bytes_xmit);
> + if (ret) {
> + return -1;
> + }
> +
> + ram_counters.transferred += bytes_xmit;
> + ram_counters.normal++;
> +
> + return 1;
> +}
> +
> +/**
> + * ram_save_encrypted_bitmap: send the encrypted page state bitmap
> + */
> +static int ram_save_encrypted_bitmap(RAMState *rs, QEMUFile *f)
> +{
> + MachineState *ms = MACHINE(qdev_get_machine());
> + MachineClass *mc = MACHINE_GET_CLASS(ms);
> + struct MachineMemoryEncryptionOps *ops = mc->memory_encryption_ops;
> +
> + save_page_header(rs, rs->f, rs->last_seen_block,
> + RAM_SAVE_FLAG_ENCRYPTED_DATA);
> + qemu_put_be32(rs->f, RAM_SAVE_ENCRYPTED_BITMAP);
> + return ops->save_outgoing_bitmap(rs->f);
> +}
> +
> +static int load_encrypted_data(QEMUFile *f, uint8_t *ptr)
> +{
> + MachineState *ms = MACHINE(qdev_get_machine());
> + MachineClass *mc = MACHINE_GET_CLASS(ms);
> + struct MachineMemoryEncryptionOps *ops = mc->memory_encryption_ops;
> + int flag;
> +
> + flag = qemu_get_be32(f);
> +
> + if (flag == RAM_SAVE_ENCRYPTED_PAGE) {
> + return ops->load_incoming_page(f, ptr);
> + } else if (flag == RAM_SAVE_ENCRYPTED_BITMAP) {
> + return ops->load_incoming_bitmap(f);
> + } else {
> + error_report("unknown encrypted flag %x", flag);
> + return 1;
> + }
> +}
> +
> /**
> * ram_save_page: send the given page to the stream
> *
> @@ -2528,6 +2602,22 @@ static bool save_compress_page(RAMState *rs, RAMBlock
> *block, ram_addr_t offset)
> return false;
> }
>
> +/**
> + * encrypted_test_bitmap: check if the page is encrypted
> + *
> + * Returns a bool indicating whether the page is encrypted.
> + */
> +static bool encrypted_test_bitmap(RAMState *rs, RAMBlock *block,
> + unsigned long page)
> +{
> + /* ROM devices contains the unencrypted data */
> + if (memory_region_is_rom(block->mr)) {
> + return false;
> + }
> +
> + return test_bit(page, block->encbmap);
> +}
> +
> /**
> * ram_save_target_page: save one target page
> *
> @@ -2548,6 +2638,17 @@ static int ram_save_target_page(RAMState *rs,
> PageSearchStatus *pss,
> return res;
> }
>
> + /*
> + * If memory encryption is enabled then use memory encryption APIs
> + * to write the outgoing buffer to the wire. The encryption APIs
> + * will take care of accessing the guest memory and re-encrypt it
> + * for the transport purposes.
> + */
> + if (memcrypt_enabled() &&
> + encrypted_test_bitmap(rs, pss->block, pss->page)) {
> + return ram_save_encrypted_page(rs, pss, last_stage);
> + }
> +
> if (save_compress_page(rs, block, offset)) {
> return 1;
> }
> @@ -3445,6 +3546,16 @@ void qemu_guest_free_page_hint(void *addr, size_t len)
> }
> }
>
> +static int ram_encrypted_save_setup(void)
> +{
> + MachineState *ms = MACHINE(qdev_get_machine());
> + MachineClass *mc = MACHINE_GET_CLASS(ms);
> + MigrationParameters *p = &migrate_get_current()->parameters;
> + struct MachineMemoryEncryptionOps *ops = mc->memory_encryption_ops;
> +
> + return ops->save_setup(p->sev_pdh, p->sev_plat_cert, p->sev_amd_cert);
> +}
> +
> /*
> * Each of ram_save_setup, ram_save_iterate and ram_save_complete has
> * long-running RCU critical section. When rcu-reclaims in the code
> @@ -3480,6 +3591,12 @@ static int ram_save_setup(QEMUFile *f, void *opaque)
>
> rcu_read_lock();
>
> + if (memcrypt_enabled()) {
> + if (ram_encrypted_save_setup()) {
> + return -1;
> + }
> + }
> +
> qemu_put_be64(f, ram_bytes_total_common(true) | RAM_SAVE_FLAG_MEM_SIZE);
>
> RAMBLOCK_FOREACH_MIGRATABLE(block) {
> @@ -3644,6 +3761,11 @@ static int ram_save_complete(QEMUFile *f, void *opaque)
> flush_compressed_data(rs);
> ram_control_after_iterate(f, RAM_CONTROL_FINISH);
>
> + /* send the page encryption state bitmap */
> + if (memcrypt_enabled()) {
> + ret = ram_save_encrypted_bitmap(rs, f);
> + }
> +
> rcu_read_unlock();
>
> multifd_send_sync_main();
> @@ -4391,7 +4513,8 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> }
>
> if (flags & (RAM_SAVE_FLAG_ZERO | RAM_SAVE_FLAG_PAGE |
> - RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) {
> + RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE |
> + RAM_SAVE_FLAG_ENCRYPTED_DATA)) {
> RAMBlock *block = ram_block_from_stream(f, flags);
>
> /*
> @@ -4505,6 +4628,12 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> break;
> }
> break;
> + case RAM_SAVE_FLAG_ENCRYPTED_DATA:
> + if (load_encrypted_data(f, host)) {
> + error_report("Failed to load encrypted data");
> + ret = -EINVAL;
> + }
> + break;
> case RAM_SAVE_FLAG_EOS:
> /* normal exit */
> multifd_recv_sync_main();
> --
> 2.17.1
>
--
Dr. David Alan Gilbert / dgilb...@redhat.com / Manchester, UK
