Re: [PATCH v6 05/14] KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command

[Steve Rutherford]

On Thu, Apr 2, 2020 at 3:31 PM Venu Busireddy <venu.busireddy@xxxxxxxxxx> wrote:
>
> On 2020-03-30 06:21:20 +0000, Ashish Kalra wrote:
> > From: Brijesh Singh <Brijesh.Singh@xxxxxxx>
> >
> > The command is used for copying the incoming buffer into the
> > SEV guest memory space.
> >
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Cc: "Radim KrÄmÃÅ" <rkrcmar@xxxxxxxxxx>
> > Cc: Joerg Roedel <joro@xxxxxxxxxx>
> > Cc: Borislav Petkov <bp@xxxxxxx>
> > Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> > Signed-off-by: Ashish Kalra <ashish.kalra@xxxxxxx>
>
> Reviewed-by: Venu Busireddy <venu.busireddy@xxxxxxxxxx>
>
> > ---
> >  .../virt/kvm/amd-memory-encryption.rst        | 24 ++++++
> >  arch/x86/kvm/svm.c                            | 79 +++++++++++++++++++
> >  include/uapi/linux/kvm.h                      |  9 +++
> >  3 files changed, 112 insertions(+)
> >
> > diff --git a/Documentation/virt/kvm/amd-memory-encryption.rst b/Documentation/virt/kvm/amd-memory-encryption.rst
> > index ef1f1f3a5b40..554aa33a99cc 100644
> > --- a/Documentation/virt/kvm/amd-memory-encryption.rst
> > +++ b/Documentation/virt/kvm/amd-memory-encryption.rst
> > @@ -351,6 +351,30 @@ On success, the 'handle' field contains a new handle and on error, a negative va
> >
> >  For more details, see SEV spec Section 6.12.
> >
> > +14. KVM_SEV_RECEIVE_UPDATE_DATA
> > +----------------------------
> > +
> > +The KVM_SEV_RECEIVE_UPDATE_DATA command can be used by the hypervisor to copy
> > +the incoming buffers into the guest memory region with encryption context
> > +created during the KVM_SEV_RECEIVE_START.
> > +
> > +Parameters (in): struct kvm_sev_receive_update_data
> > +
> > +Returns: 0 on success, -negative on error
> > +
> > +::
> > +
> > +        struct kvm_sev_launch_receive_update_data {
> > +                __u64 hdr_uaddr;        /* userspace address containing the packet header */
> > +                __u32 hdr_len;
> > +
> > +                __u64 guest_uaddr;      /* the destination guest memory region */
> > +                __u32 guest_len;
> > +
> > +                __u64 trans_uaddr;      /* the incoming buffer memory region  */
> > +                __u32 trans_len;
> > +        };
> > +
> >  References
> >  ==========
> >
> > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> > index 038b47685733..5fc5355536d7 100644
> > --- a/arch/x86/kvm/svm.c
> > +++ b/arch/x86/kvm/svm.c
> > @@ -7497,6 +7497,82 @@ static int sev_receive_start(struct kvm *kvm, struct kvm_sev_cmd *argp)
> >       return ret;
> >  }
> >
> > +static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
> > +{
> > +     struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
> > +     struct kvm_sev_receive_update_data params;
> > +     struct sev_data_receive_update_data *data;
> > +     void *hdr = NULL, *trans = NULL;
> > +     struct page **guest_page;
> > +     unsigned long n;
> > +     int ret, offset;
> > +
> > +     if (!sev_guest(kvm))
> > +             return -EINVAL;
> > +
> > +     if (copy_from_user(&params, (void __user *)(uintptr_t)argp->data,
> > +                     sizeof(struct kvm_sev_receive_update_data)))
> > +             return -EFAULT;
> > +
> > +     if (!params.hdr_uaddr || !params.hdr_len ||
> > +         !params.guest_uaddr || !params.guest_len ||
> > +         !params.trans_uaddr || !params.trans_len)
> > +             return -EINVAL;
> > +
> > +     /* Check if we are crossing the page boundary */
> > +     offset = params.guest_uaddr & (PAGE_SIZE - 1);
> > +     if ((params.guest_len + offset > PAGE_SIZE))
> > +             return -EINVAL;

Check for overflow.
>
> > +
> > +     hdr = psp_copy_user_blob(params.hdr_uaddr, params.hdr_len);
> > +     if (IS_ERR(hdr))
> > +             return PTR_ERR(hdr);
> > +
> > +     trans = psp_copy_user_blob(params.trans_uaddr, params.trans_len);
> > +     if (IS_ERR(trans)) {
> > +             ret = PTR_ERR(trans);
> > +             goto e_free_hdr;
> > +     }
> > +
> > +     ret = -ENOMEM;
> > +     data = kzalloc(sizeof(*data), GFP_KERNEL);
> > +     if (!data)
> > +             goto e_free_trans;
> > +
> > +     data->hdr_address = __psp_pa(hdr);
> > +     data->hdr_len = params.hdr_len;
> > +     data->trans_address = __psp_pa(trans);
> > +     data->trans_len = params.trans_len;
> > +
> > +     /* Pin guest memory */
> > +     ret = -EFAULT;
> > +     guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
> > +                                 PAGE_SIZE, &n, 0);
> > +     if (!guest_page)
> > +             goto e_free;
> > +
> > +     /* The RECEIVE_UPDATE_DATA command requires C-bit to be always set. */
> > +     data->guest_address = (page_to_pfn(guest_page[0]) << PAGE_SHIFT) +
> > +                             offset;
> > +     data->guest_address |= sev_me_mask;
> > +     data->guest_len = params.guest_len;
> > +     data->handle = sev->handle;
> > +
> > +     ret = sev_issue_cmd(kvm, SEV_CMD_RECEIVE_UPDATE_DATA, data,
> > +                             &argp->error);
> > +
> > +     sev_unpin_memory(kvm, guest_page, n);
> > +
> > +e_free:
> > +     kfree(data);
> > +e_free_trans:
> > +     kfree(trans);
> > +e_free_hdr:
> > +     kfree(hdr);
> > +
> > +     return ret;
> > +}
> > +
> >  static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> >  {
> >       struct kvm_sev_cmd sev_cmd;
> > @@ -7553,6 +7629,9 @@ static int svm_mem_enc_op(struct kvm *kvm, void __user *argp)
> >       case KVM_SEV_RECEIVE_START:
> >               r = sev_receive_start(kvm, &sev_cmd);
> >               break;
> > +     case KVM_SEV_RECEIVE_UPDATE_DATA:
> > +             r = sev_receive_update_data(kvm, &sev_cmd);
> > +             break;
> >       default:
> >               r = -EINVAL;
> >               goto out;
> > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> > index 74764b9db5fa..4e80c57a3182 100644
> > --- a/include/uapi/linux/kvm.h
> > +++ b/include/uapi/linux/kvm.h
> > @@ -1588,6 +1588,15 @@ struct kvm_sev_receive_start {
> >       __u32 session_len;
> >  };
> >
> > +struct kvm_sev_receive_update_data {
> > +     __u64 hdr_uaddr;
> > +     __u32 hdr_len;
> > +     __u64 guest_uaddr;
> > +     __u32 guest_len;
> > +     __u64 trans_uaddr;
> > +     __u32 trans_len;
> > +};
> > +
> >  #define KVM_DEV_ASSIGN_ENABLE_IOMMU  (1 << 0)
> >  #define KVM_DEV_ASSIGN_PCI_2_3               (1 << 1)
> >  #define KVM_DEV_ASSIGN_MASK_INTX     (1 << 2)
> > --
> > 2.17.1
> >
Otherwise looks fine to my eye.
Reviewed-by: Steve Rutherford <srutherford@xxxxxxxxxx>