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

[Singh, Brijesh]

On 7/11/19 12:47 PM, Dr. David Alan Gilbert wrote:
> * Singh, Brijesh (address@hidden) 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 <<address@hidden>>
>> ---
>>   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.
> 

Agreed, I will add comment in API header about this. The value of zero
means success and anything else is failure.


>> +}
>> +
>> +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 / address@hidden / Manchester, UK
>