Re: [RFC PATCH 3/6] i386/sev: initialize SNP context

Dov Murik
2021-07-15T09:32:41Z

Hi Brijesh,

On 10/07/2021 0:55, Brijesh Singh wrote:
> When SEV-SNP is enabled, the KVM_SNP_INIT command is used to initialize
> the platform. The command checks whether SNP is enabled in the KVM, if
> enabled then it allocate a new ASID from the SNP pool and calls the

s/allocate/allocates/

> firmware to initialize the all the resources.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> target/i386/sev.c | 24 +++++++++++++++++++++---
> target/i386/sev_i386.h | 1 +
> 2 files changed, 22 insertions(+), 3 deletions(-)
>
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 6b238ef969..84ae244af0 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -583,10 +583,17 @@ sev_enabled(void)
> return !!sev_guest;
> }
>
> +bool
> +sev_snp_enabled(void)
> +{
> + return sev_guest->snp;
> +}
> +
> bool
> sev_es_enabled(void)
> {
> - return sev_enabled() && (sev_guest->policy & SEV_POLICY_ES);
> + return sev_snp_enabled() ||
> + (sev_enabled() && (sev_guest->policy & SEV_POLICY_ES));
> }
>

Just making sure I understand:

* sev_enabled() returns true for SEV or newer (SEV or SEV-ES or
SEV-SNP).
* sev_es_enabled() returns true for SEV-ES or newer (SEV-ES or SEV-SNP).
* sev_snp_enabled() returns true for SEV-SNP or newer (currently only
SEV-SNP).

Is that indeed the intention?

-Dov

> uint64_t
> @@ -1008,6 +1015,7 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
> uint32_t ebx;
> uint32_t host_cbitpos;
> struct sev_user_data_status status = {};
> + void *init_args = NULL;
>
> if (!sev) {
> return 0;
> @@ -1061,7 +1069,17 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
> sev->api_major = status.api_major;
> sev->api_minor = status.api_minor;
>
> - if (sev_es_enabled()) {
> + if (sev_snp_enabled()) {
> + if (!kvm_kernel_irqchip_allowed()) {
> + error_report("%s: SEV-SNP guests require in-kernel irqchip support",
> + __func__);
> + goto err;
> + }
> +
> + cmd = KVM_SEV_SNP_INIT;
> + init_args = (void *)&sev->snp_config.init;
> +
> + } else if (sev_es_enabled()) {
> if (!kvm_kernel_irqchip_allowed()) {
> error_report("%s: SEV-ES guests require in-kernel irqchip support",
> __func__);
> @@ -1080,7 +1098,7 @@ int sev_kvm_init(ConfidentialGuestSupport *cgs, Error **errp)
> }
>
> trace_kvm_sev_init();
> - ret = sev_ioctl(sev->sev_fd, cmd, NULL, &fw_error);
> + ret = sev_ioctl(sev->sev_fd, cmd, init_args, &fw_error);
> if (ret) {
> error_setg(errp, "%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 ae6d840478..e0e1a599be 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_es_enabled(void);
> +extern bool sev_snp_enabled(void);
> extern uint64_t sev_get_me_mask(void);
> extern SevInfo *sev_get_info(void);
> extern uint32_t sev_get_cbit_position(void);
>