Re: [Qemu-devel] [PATCH v2 02/13] kvm: introduce high-level API to support encrypted page migration

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Singh, Brijesh (brijesh.singh@amd.com) wrote:
> When memory encryption is enabled in VM, the guest pages will be
> encrypted with the guest-specific key, to protect the confidentiality
> of data in transit. To support the live migration we need to use
> platform specific hooks to access the guest memory.
> 
> The kvm_memcrypt_save_outgoing_page() can be used by the sender to write
> the encrypted pages and metadata associated with it on the socket.
> 
> The kvm_memcrypt_load_incoming_page() can be used by receiver to read the
> incoming encrypted pages from the socket and load into the guest memory.
> 
> Signed-off-by: Brijesh Singh <<brijesh.singh@amd.com>>
> ---
>  accel/kvm/kvm-all.c    | 27 +++++++++++++++++++++++++++
>  accel/kvm/sev-stub.c   | 11 +++++++++++
>  accel/stubs/kvm-stub.c | 12 ++++++++++++
>  include/sysemu/kvm.h   | 12 ++++++++++++
>  include/sysemu/sev.h   |  3 +++
>  5 files changed, 65 insertions(+)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 3d86ae5052..162a2d5085 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -110,6 +110,10 @@ struct KVMState
>      /* memory encryption */
>      void *memcrypt_handle;
>      int (*memcrypt_encrypt_data)(void *handle, uint8_t *ptr, uint64_t len);
> +    int (*memcrypt_save_outgoing_page)(void *ehandle, QEMUFile *f,
> +            uint8_t *ptr, uint32_t sz, uint64_t *bytes_sent);
> +    int (*memcrypt_load_incoming_page)(void *ehandle, QEMUFile *f,
> +            uint8_t *ptr);
>  };
>  
>  KVMState *kvm_state;
> @@ -165,6 +169,29 @@ int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
>      return 1;
>  }
>  
> +int kvm_memcrypt_save_outgoing_page(QEMUFile *f, uint8_t *ptr,
> +                                    uint32_t size, uint64_t *bytes_sent)
> +{
> +    if (kvm_state->memcrypt_handle &&
> +        kvm_state->memcrypt_save_outgoing_page) {
> +        return kvm_state->memcrypt_save_outgoing_page(kvm_state->memcrypt_handle,
> +                    f, ptr, size, bytes_sent);
> +    }
> +
> +    return 1;

This needs to be commented saying what the return values mean.
I'm not sure what '1' means for the case when this didn't have
encryption support.

> +}
> +
> +int kvm_memcrypt_load_incoming_page(QEMUFile *f, uint8_t *ptr)
> +{
> +    if (kvm_state->memcrypt_handle &&
> +        kvm_state->memcrypt_load_incoming_page) {
> +        return kvm_state->memcrypt_load_incoming_page(kvm_state->memcrypt_handle,
> +                    f, ptr);
> +    }
> +
> +    return 1;
> +}
> +
>  static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
>  {
>      KVMState *s = kvm_state;
> diff --git a/accel/kvm/sev-stub.c b/accel/kvm/sev-stub.c
> index 4f97452585..c12a8e005e 100644
> --- a/accel/kvm/sev-stub.c
> +++ b/accel/kvm/sev-stub.c
> @@ -24,3 +24,14 @@ void *sev_guest_init(const char *id)
>  {
>      return NULL;
>  }
> +
> +int sev_save_outgoing_page(void *handle, QEMUFile *f, uint8_t *ptr,
> +                           uint32_t size, uint64_t *bytes_sent)
> +{
> +    return 1;
> +}
> +
> +int sev_load_incoming_page(void *handle, QEMUFile *f, uint8_t *ptr)
> +{
> +    return 1;
> +}
> diff --git a/accel/stubs/kvm-stub.c b/accel/stubs/kvm-stub.c
> index 6feb66ed80..e14b879531 100644
> --- a/accel/stubs/kvm-stub.c
> +++ b/accel/stubs/kvm-stub.c
> @@ -114,6 +114,18 @@ int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
>    return 1;
>  }
>  
> +int kvm_memcrypt_save_outgoing_page(QEMUFile *f, uint8_t *ptr,
> +                                    uint32_t size, uint64_t *bytes_sent)
> +{
> +    return 1;
> +}
> +
> +int kvm_memcrypt_load_incoming_page(QEMUFile *f, uint8_t *ptr)
> +{
> +    return 1;
> +}
> +
> +
>  #ifndef CONFIG_USER_ONLY
>  int kvm_irqchip_add_msi_route(KVMState *s, int vector, PCIDevice *dev)
>  {
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index acd90aebb6..bb6bcc143c 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -247,6 +247,18 @@ bool kvm_memcrypt_enabled(void);
>   */
>  int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len);
>  
> +/**
> + * kvm_memcrypt_save_outgoing_buffer - encrypt the outgoing buffer
> + * and write to the wire.
> + */
> +int kvm_memcrypt_save_outgoing_page(QEMUFile *f, uint8_t *ptr, uint32_t size,
> +                                    uint64_t *bytes_sent);
> +
> +/**
> + * kvm_memcrypt_load_incoming_buffer - read the encrypt incoming buffer and copy
> + * the buffer into the guest memory space.
> + */
> +int kvm_memcrypt_load_incoming_page(QEMUFile *f, uint8_t *ptr);
>  
>  #ifdef NEED_CPU_H
>  #include "cpu.h"
> diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
> index 98c1ec8d38..752a71b1c0 100644
> --- a/include/sysemu/sev.h
> +++ b/include/sysemu/sev.h
> @@ -18,4 +18,7 @@
>  
>  void *sev_guest_init(const char *id);
>  int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len);
> +int sev_save_outgoing_page(void *handle, QEMUFile *f, uint8_t *ptr,
> +                           uint32_t size, uint64_t *bytes_sent);
> +int sev_load_incoming_page(void *handle, QEMUFile *f, uint8_t *ptr);
>  #endif
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK