lkml.org 
[lkml]   [2020]   [Mar]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 04/12] KVM: SVM: Add support for KVM_SEV_RECEIVE_START command
On Mon, Mar 09, 2020 at 06:41:02PM -0700, Steve Rutherford wrote:
> > +static int sev_receive_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> > +{
> > + struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> > + struct sev_data_receive_start *start;
> > + struct kvm_sev_receive_start params;
> > + int *error = &argp->error;
> > + void *session_data;
> > + void *pdh_data;
> > + int ret;
> > +
> > + if (!sev_guest(kvm))
> > + return -ENOTTY;
> > +
> > + /* Get parameter from the userspace */
> > + if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> > + sizeof(struct kvm_sev_receive_start)))
> > + return -EFAULT;
> > +
> > + /* some sanity checks */
> > + if (!params.pdh_uaddr || !params.pdh_len ||
> > + !params.session_uaddr || !params.session_len)
> > + return -EINVAL;
> > +
> > + pdh_data = psp_copy_user_blob(params.pdh_uaddr, params.pdh_len);
> > + if (IS_ERR(pdh_data))
> > + return PTR_ERR(pdh_data);
> > +
> > + session_data = psp_copy_user_blob(params.session_uaddr,
> > + params.session_len);
> > + if (IS_ERR(session_data)) {
> > + ret = PTR_ERR(session_data);
> > + goto e_free_pdh;
> > + }
> > +
> > + ret = -ENOMEM;
> > + start = kzalloc(sizeof(*start), GFP_KERNEL);
> > + if (!start)
> > + goto e_free_session;
> > +
> > + start->handle = params.handle;
> > + start->policy = params.policy;
> > + start->pdh_cert_address = __psp_pa(pdh_data);
> > + start->pdh_cert_len = params.pdh_len;
> > + start->session_address = __psp_pa(session_data);
> > + start->session_len = params.session_len;
> > +
> > + /* create memory encryption context */
>
> Set ret to a different value here, since otherwise this will look like -ENOMEM.

But, ret will be the value returned by __sev_issue_cmd(), so why will it
look like -ENOMEM ?

>
> > + ret = __sev_issue_cmd(argp->sev_fd, SEV_CMD_RECEIVE_START, start,
> > + error);
> > + if (ret)
> > + goto e_free;
> > +
> > + /* Bind ASID to this guest */
>
> Ideally, set ret to another distinct value, since the error spaces for
> these commands overlap, so you won't be sure which had the problem.
> You also wouldn't be sure if one succeeded and the other failed vs
> both failing.

Both commands "may" return the same error code as set by sev_do_cmd(), but
then we need that very specific error code, sev_do_cmd() can't return
different error codes for each command it is issuing ?

>
> > + ret = sev_bind_asid(kvm, start->handle, error);
> > + if (ret)
> > + goto e_free;
> > +

Thanks,
Ashish

\
 
 \ /
  Last update: 2020-03-12 01:43    [W:0.109 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site