Re: [PATCH v3 1/5] sev/i386: Add initial support for SEV-ES

[Tom Lendacky <thomas.lendacky@amd.com>]

On 9/21/20 1:45 AM, Dov Murik wrote:
> On 16/09/2020 0:29, Tom Lendacky wrote:
>> From: Tom Lendacky <thomas.lendacky@amd.com>
>>
>> Provide initial support for SEV-ES. This includes creating a function to
>> indicate the guest is an SEV-ES guest (which will return false until all
>> support is in place), performing the proper SEV initialization and
>> ensuring that the guest CPU state is measured as part of the launch.
>>
>> Co-developed-by: Jiri Slaby <jslaby@suse.cz>
>> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
>> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
>> ---
>>   target/i386/cpu.c      |  1 +
>>   target/i386/sev-stub.c |  5 +++++
>>   target/i386/sev.c      | 46 ++++++++++++++++++++++++++++++++++++++++--
>>   target/i386/sev_i386.h |  1 +
>>   4 files changed, 51 insertions(+), 2 deletions(-)
>>
>> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
>> index 588f32e136..bbbe581d35 100644
>> --- a/target/i386/cpu.c
>> +++ b/target/i386/cpu.c
>> @@ -5969,6 +5969,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t
>> index, uint32_t count,
>>           break;
>>       case 0x8000001F:
>>           *eax = sev_enabled() ? 0x2 : 0;
>> +        *eax |= sev_es_enabled() ? 0x8 : 0;
>>           *ebx = sev_get_cbit_position();
>>           *ebx |= sev_get_reduced_phys_bits() << 6;
>>           *ecx = 0;
>> diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
>> index 88e3f39a1e..040ac90563 100644
>> --- a/target/i386/sev-stub.c
>> +++ b/target/i386/sev-stub.c
>> @@ -49,3 +49,8 @@ SevCapability *sev_get_capabilities(Error **errp)
>>       error_setg(errp, "SEV is not available in this QEMU");
>>       return NULL;
>>   }
>> +
>> +bool sev_es_enabled(void)
>> +{
>> +    return false;
>> +}
>> diff --git a/target/i386/sev.c b/target/i386/sev.c
>> index c3ecf86704..6c9cd0854b 100644
>> --- a/target/i386/sev.c
>> +++ b/target/i386/sev.c
>> @@ -359,6 +359,12 @@ sev_enabled(void)
>>       return !!sev_guest;
>>   }
>>
>> +bool
>> +sev_es_enabled(void)
>> +{
>> +    return false;
>> +}
>> +
>>   uint64_t
>>   sev_get_me_mask(void)
>>   {
>> @@ -578,6 +584,22 @@ sev_launch_update_data(SevGuestState *sev, uint8_t
>> *addr, uint64_t len)
>>       return ret;
>>   }
>>
>> +static int
>> +sev_launch_update_vmsa(SevGuestState *sev)
>> +{
>> +    int ret, fw_error;
>> +
>> +    ret = sev_ioctl(sev->sev_fd, KVM_SEV_LAUNCH_UPDATE_VMSA, NULL,
>> &fw_error);
>> +    if (ret) {
>> +        error_report("%s: LAUNCH_UPDATE_VMSA ret=%d fw_error=%d '%s'",
>> +                __func__, ret, fw_error, fw_error_to_str(fw_error));
>> +        goto err;
> 
> goto (and the err: label) is not needed.

Yup, will remove both.

> 
>> +    }
>> +
>> +err:
>> +    return ret;
>> +}
>> +
>>   static void
>>   sev_launch_get_measure(Notifier *notifier, void *unused)
>>   {
>> @@ -590,6 +612,14 @@ sev_launch_get_measure(Notifier *notifier, void
>> *unused)
>>           return;
>>       }
>>
>> +    if (sev_es_enabled()) {
>> +        /* measure all the VM save areas before getting launch_measure */
>> +        ret = sev_launch_update_vmsa(sev);
>> +        if (ret) {
>> +            exit(1);
> 
> Other error cases in this function just return on error. Why quit QEMU here?

This is inside an void return function so an error can't be returned. It
matches what happens if sev_launch_finish() fails. To that end, a
LAUNCH_MEASURE error should probably exit(), also.

Thanks,
Tom

> 
>> +        }
>> +    }
>> +
>>       measurement = g_new0(struct kvm_sev_launch_measure, 1);
>>
>>       /* query the measurement blob length */
>> @@ -684,7 +714,7 @@ sev_guest_init(const char *id)
>>   {
>>       SevGuestState *sev;
>>       char *devname;
>> -    int ret, fw_error;
>> +    int ret, fw_error, cmd;
>>       uint32_t ebx;
>>       uint32_t host_cbitpos;
>>       struct sev_user_data_status status = {};
>> @@ -745,8 +775,20 @@ sev_guest_init(const char *id)
>>       sev->api_major = status.api_major;
>>       sev->api_minor = status.api_minor;
>>
>> +    if (sev_es_enabled()) {
>> +        if (!(status.flags & SEV_STATUS_FLAGS_CONFIG_ES)) {
>> +            error_report("%s: guest policy requires SEV-ES, but "
>> +                         "host SEV-ES support unavailable",
>> +                         __func__);
>> +            goto err;
>> +        }
>> +        cmd = KVM_SEV_ES_INIT;
>> +    } else {
>> +        cmd = KVM_SEV_INIT;
>> +    }
>> +
>>       trace_kvm_sev_init();
>> -    ret = sev_ioctl(sev->sev_fd, KVM_SEV_INIT, NULL, &fw_error);
>> +    ret = sev_ioctl(sev->sev_fd, cmd, NULL, &fw_error);
>>       if (ret) {
>>           error_report("%s: failed to initialize ret=%d fw_error=%d '%s'",
>>                        __func__, ret, fw_error, fw_error_to_str(fw_error));
>> diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
>> index 4db6960f60..4f9a5e9b21 100644
>> --- a/target/i386/sev_i386.h
>> +++ b/target/i386/sev_i386.h
>> @@ -29,6 +29,7 @@
>>   #define SEV_POLICY_SEV          0x20
>>
>>   extern bool sev_enabled(void);
>> +extern bool sev_es_enabled(void);
>>   extern uint64_t sev_get_me_mask(void);
>>   extern SevInfo *sev_get_info(void);
>>   extern uint32_t sev_get_cbit_position(void);
>>