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

[Dov Murik <dovmurik@linux.vnet.ibm.com>]

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.

> +    }
> +
> +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?

> +        }
> +    }
> +
>       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);
>