Re: [Qemu-devel] [PATCH v2 10/13] target/i386: sev: add support to load incoming encrypted page

[Singh, Brijesh]

On 7/12/19 6:02 AM, Dr. David Alan Gilbert wrote:
> * Singh, Brijesh (address@hidden) wrote:
>> The sev_load_incoming_page() provide the implementation to read the
>> incoming guest private pages from the socket and load it into the guest
>> memory. The routines uses the RECEIVE_START command to create the
>> incoming encryption context on the first call then uses the
>> RECEIEVE_UPDATE_DATA command to load the encrypted pages into the guest
>> memory. After migration is completed, we issue the RECEIVE_FINISH command
>> to transition the SEV guest to the runnable state so that it can be
>> executed.
>>
>> Signed-off-by: Brijesh Singh <address@hidden>
>> ---
>>   accel/kvm/kvm-all.c      |   1 +
>>   target/i386/sev.c        | 126 ++++++++++++++++++++++++++++++++++++++-
>>   target/i386/trace-events |   3 +
>>   3 files changed, 129 insertions(+), 1 deletion(-)
>>
>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
>> index a9fb447248..7f94dba6f9 100644
>> --- a/accel/kvm/kvm-all.c
>> +++ b/accel/kvm/kvm-all.c
>> @@ -1793,6 +1793,7 @@ 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;
>>       }
>>   
>>       ret = kvm_arch_init(ms, s);
>> diff --git a/target/i386/sev.c b/target/i386/sev.c
>> index 28b36c8035..09a62d6f88 100644
>> --- a/target/i386/sev.c
>> +++ b/target/i386/sev.c
>> @@ -708,13 +708,34 @@ sev_launch_finish(SEVState *s)
>>       }
>>   }
>>   
>> +static int
>> +sev_receive_finish(SEVState *s)
>> +{
>> +    int error, ret = 1;
>> +
>> +    trace_kvm_sev_receive_finish();
>> +    ret = sev_ioctl(s->sev_fd, KVM_SEV_RECEIVE_FINISH, 0, &error);
>> +    if (ret) {
>> +        error_report("%s: RECEIVE_FINISH ret=%d fw_error=%d '%s'",
>> +                __func__, ret, error, fw_error_to_str(error));
>> +        goto err;
>> +    }
>> +
>> +    sev_set_guest_state(SEV_STATE_RUNNING);
>> +err:
>> +    return ret;
>> +}
>> +
>> +
>>   static void
>>   sev_vm_state_change(void *opaque, int running, RunState state)
>>   {
>>       SEVState *s = opaque;
>>   
>>       if (running) {
>> -        if (!sev_check_state(SEV_STATE_RUNNING)) {
>> +        if (sev_check_state(SEV_STATE_RECEIVE_UPDATE)) {
>> +            sev_receive_finish(s);
>> +        } else if (!sev_check_state(SEV_STATE_RUNNING)) {
>>               sev_launch_finish(s);
>>           }
>>       }
>> @@ -1065,6 +1086,109 @@ int sev_save_outgoing_page(void *handle, QEMUFile 
>> *f, uint8_t *ptr,
>>       return sev_send_update_data(s, f, ptr, sz, bytes_sent);
>>   }
>>   
>> +static int
>> +sev_receive_start(QSevGuestInfo *sev, QEMUFile *f)
>> +{
>> +    int ret = 1;
>> +    int fw_error;
>> +    struct kvm_sev_receive_start *start;
>> +    gchar *session = NULL, *pdh_cert = NULL;
>> +
>> +    start = g_new0(struct kvm_sev_receive_start, 1);
> 
> Same as the send patch; these are tiny so may as well be on the stack
> 
>> +    /* get SEV guest handle */
>> +    start->handle = object_property_get_int(OBJECT(sev), "handle",
>> +            &error_abort);
>> +
>> +    /* get the source policy */
>> +    start->policy = qemu_get_be32(f);
>> +
>> +    /* get source PDH key */
>> +    start->pdh_len = qemu_get_be32(f);
> 
> You might want to bound the sizes of pdh_len and session_len
> on reading; if the migration stream is badly corrupt you could
> end up allocating and then trying to read a few GB ofjunk off the wire.
> 

Good point. Noted.


>> +    pdh_cert = g_new(gchar, start->pdh_len);
>> +    qemu_get_buffer(f, (uint8_t *)pdh_cert, start->pdh_len);
>> +    start->pdh_uaddr = (unsigned long)pdh_cert;
>> +
>> +    /* get source session data */
>> +    start->session_len = qemu_get_be32(f);
>> +    session = g_new(gchar, start->session_len);
>> +    qemu_get_buffer(f, (uint8_t *)session, start->session_len);
>> +    start->session_uaddr = (unsigned long)session;
>> +
>> +    trace_kvm_sev_receive_start(start->policy, session, pdh_cert);
>> +
>> +    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_RECEIVE_START, start, 
>> &fw_error);
>> +    if (ret < 0) {
>> +        error_report("Error RECEIVE_START ret=%d fw_error=%d '%s'",
>> +                ret, fw_error, fw_error_to_str(fw_error));
>> +        goto err;
>> +    }
>> +
>> +    object_property_set_int(OBJECT(sev), start->handle, "handle", 
>> &error_abort);
>> +    sev_set_guest_state(SEV_STATE_RECEIVE_UPDATE);
>> +err:
>> +    g_free(start);
>> +    g_free(session);
>> +    g_free(pdh_cert);
>> +
>> +    return ret;
>> +}
>> +
>> +static int sev_receive_update_data(QEMUFile *f, uint8_t *ptr)
>> +{
>> +    int ret = 1, fw_error = 0;
>> +    gchar *hdr = NULL, *trans = NULL;
>> +    struct kvm_sev_receive_update_data *update;
>> +
>> +    update = g_new0(struct kvm_sev_receive_update_data, 1);
> 
> Similar comments to the _start function
> 

Noted.


>> +    /* get packet header */
>> +    update->hdr_len = qemu_get_be32(f);
>> +    hdr = g_new(gchar, update->hdr_len);
>> +    qemu_get_buffer(f, (uint8_t *)hdr, update->hdr_len);
>> +    update->hdr_uaddr = (unsigned long)hdr;
>> +
>> +    /* get transport buffer */
>> +    update->trans_len = qemu_get_be32(f);
>> +    trans = g_new(gchar, update->trans_len);
>> +    update->trans_uaddr = (unsigned long)trans;
>> +    qemu_get_buffer(f, (uint8_t *)update->trans_uaddr, update->trans_len);
>> +
>> +    update->guest_uaddr = (unsigned long) ptr;
>> +    update->guest_len = update->trans_len;
>> +
>> +    trace_kvm_sev_receive_update_data(trans, ptr, update->guest_len,
>> +            hdr, update->hdr_len);
>> +
>> +    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_RECEIVE_UPDATE_DATA,
>> +                    update, &fw_error);
>> +    if (ret) {
>> +        error_report("Error RECEIVE_UPDATE_DATA ret=%d fw_error=%d '%s'",
>> +                ret, fw_error, fw_error_to_str(fw_error));
>> +        goto err;
>> +    }
>> +err:
>> +    g_free(trans);
>> +    g_free(update);
>> +    g_free(hdr);
>> +    return ret;
>> +}
>> +
>> +int sev_load_incoming_page(void *handle, QEMUFile *f, uint8_t *ptr)
>> +{
>> +    SEVState *s = (SEVState *)handle;
>> +
>> +    /* If this is first buffer and SEV is not in recieiving state then
>> +     * use RECEIVE_START command to create a encryption context.
>> +     */
>> +    if (!sev_check_state(SEV_STATE_RECEIVE_UPDATE) &&
>> +        sev_receive_start(s->sev_info, f)) {
>> +        return 1;
>> +    }
>> +
>> +    return sev_receive_update_data(f, ptr);
>> +}
>> +
>>   static void
>>   sev_register_types(void)
>>   {
>> diff --git a/target/i386/trace-events b/target/i386/trace-events
>> index b41516cf9f..609752cca7 100644
>> --- a/target/i386/trace-events
>> +++ b/target/i386/trace-events
>> @@ -18,3 +18,6 @@ kvm_sev_launch_finish(void) ""
>>   kvm_sev_send_start(uint64_t pdh, int l1, uint64_t plat, int l2, uint64_t 
>> amd, int l3) "pdh 0x%" PRIx64 " len %d plat 0x%" PRIx64 " len %d amd 0x%" 
>> PRIx64 " len %d"
>>   kvm_sev_send_update_data(void *src, void *dst, int len) "guest %p trans %p 
>> len %d"
>>   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) ""
>> -- 
>> 2.17.1
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK
>