Re: [Qemu-devel] [PATCH v9 16/29] sev/i386: add command to encrypt guest memory region

[Brijesh Singh]

On 2/16/18 9:47 AM, Dr. David Alan Gilbert wrote:
> * Brijesh Singh (address@hidden) wrote:
>> The KVM_SEV_LAUNCH_UPDATE_DATA command is used to encrypt a guest memory
>> region using the VM Encryption Key created using LAUNCH_START.
>>
>> Cc: Paolo Bonzini <address@hidden>
>> Cc: Richard Henderson <address@hidden>
>> Cc: Eduardo Habkost <address@hidden>
>> Signed-off-by: Brijesh Singh <address@hidden>
>> ---
>>  accel/kvm/kvm-all.c      |  2 ++
>>  include/sysemu/sev.h     |  1 +
>>  stubs/sev.c              |  5 +++++
>>  target/i386/sev.c        | 49 
>> ++++++++++++++++++++++++++++++++++++++++++++++++
>>  target/i386/trace-events |  1 +
>>  5 files changed, 58 insertions(+)
>>
>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
>> index 4468c8fe002c..4974c00c46fb 100644
>> --- a/accel/kvm/kvm-all.c
>> +++ b/accel/kvm/kvm-all.c
>> @@ -1679,6 +1679,8 @@ static int kvm_init(MachineState *ms)
>>          if (!kvm_state->memcrypt_handle) {
>>              goto err;
>>          }
>> +
>> +        kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
>>      }
>>  
>>      ret = kvm_arch_init(ms, s);
>> diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
>> index 5c8c549b68ec..c16102b05ec4 100644
>> --- a/include/sysemu/sev.h
>> +++ b/include/sysemu/sev.h
>> @@ -69,5 +69,6 @@ struct SEVState {
>>  typedef struct SEVState SEVState;
>>  
>>  void *sev_guest_init(const char *id);
>> +int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len);
>>  
>>  #endif
>> diff --git a/stubs/sev.c b/stubs/sev.c
>> index 24c7b0c3e04d..74182bb545e2 100644
>> --- a/stubs/sev.c
>> +++ b/stubs/sev.c
>> @@ -15,6 +15,11 @@
>>  #include "qemu-common.h"
>>  #include "sysemu/sev.h"
>>  
>> +int sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
>> +{
>> +    return 1;
>> +}
>> +
>>  SevState sev_get_current_state(void)
>>  {
>>      return SEV_STATE_UNINIT;
>> diff --git a/target/i386/sev.c b/target/i386/sev.c
>> index 6f767084fd57..04a64b5bc61d 100644
>> --- a/target/i386/sev.c
>> +++ b/target/i386/sev.c
>> @@ -90,6 +90,12 @@ fw_error_to_str(int code)
>>      return sev_fw_errlist[code];
>>  }
>>  
>> +static bool
>> +sev_check_state(SevState state)
>> +{
>> +    return current_sev_guest_state == state ? true : false;
>> +}
>> +
>>  static void
>>  sev_set_guest_state(SevState new_state)
>>  {
>> @@ -466,6 +472,36 @@ sev_launch_start(SEVState *s)
>>      return 0;
>>  }
>>  
>> +static int
>> +sev_launch_update_data(uint8_t *addr, uint64_t len)
>> +{
>> +    int ret, fw_error;
>> +    struct kvm_sev_launch_update_data *update;
>> +
>> +    if (addr == NULL || len <= 0) {
>> +        return 1;
>> +    }
>> +
>> +    update = g_malloc0(sizeof(*update));
>> +    if (!update) {
>> +        return 1;
>> +    }
>>
> Keep checking for the g_malloc0 use - it will never return NULL;
> if you want it to be safe from running out of memory use g_try_malloc0
> otherwise you can just remove the !update check.
> Also it's better to use the g_new0 macro (or g_try_new0) - it's neater
> and avoids the whole sizeof thing.
> (You have that in a bunch of the patches)

I didn't realized that g_malloc0() will never return NULL. I checked
just glib doc, if v10 is needed then I can remove them all or can submit
a follow-up patch.

thanks


> Dave
>
>> +    update->uaddr = (__u64)addr;
>> +    update->len = len;
>> +    trace_kvm_sev_launch_update_data(addr, len);
>> +    ret = sev_ioctl(KVM_SEV_LAUNCH_UPDATE_DATA, update, &fw_error);
>> +    if (ret) {
>> +        error_report("%s: LAUNCH_UPDATE ret=%d fw_error=%d '%s'",
>> +                __func__, ret, fw_error, fw_error_to_str(fw_error));
>> +        goto err;
>> +    }
>> +
>> +err:
>> +    g_free(update);
>> +    return ret;
>> +}
>> +
>>  void *
>>  sev_guest_init(const char *id)
>>  {
>> @@ -540,6 +576,19 @@ err:
>>      return NULL;
>>  }
>>  
>> +int
>> +sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
>> +{
>> +    assert(handle);
>> +
>> +    /* if SEV is in update state then encrypt the data else do nothing */
>> +    if (sev_check_state(SEV_STATE_LUPDATE)) {
>> +        return sev_launch_update_data(ptr, len);
>> +    }
>> +
>> +    return 0;
>> +}
>> +
>>  static void
>>  sev_register_types(void)
>>  {
>> diff --git a/target/i386/trace-events b/target/i386/trace-events
>> index 9402251e9991..c0cd8e93217f 100644
>> --- a/target/i386/trace-events
>> +++ b/target/i386/trace-events
>> @@ -12,3 +12,4 @@ kvm_memcrypt_register_region(void *addr, size_t len) "addr 
>> %p len 0x%lu"
>>  kvm_memcrypt_unregister_region(void *addr, size_t len) "addr %p len 0x%lu"
>>  kvm_sev_change_state(const char *old, const char *new) "%s -> %s"
>>  kvm_sev_launch_start(int policy, void *session, void *pdh) "policy 0x%x 
>> session %p pdh %p"
>> +kvm_sev_launch_update_data(void *addr, uint64_t len) "addr %p len 0x%" 
>> PRIu64
>> -- 
>> 2.14.3
>>
> --
> Dr. David Alan Gilbert / address@hidden / Manchester, UK