Re: [PATCH v6 40/42] virt: Add SEV-SNP guest driver

Dov Murik
2021-10-10T17:52:13Z

Hi Brijesh,

On 08/10/2021 21:04, Brijesh Singh wrote:
> SEV-SNP specification provides the guest a mechanisum to communicate with
> the PSP without risk from a malicious hypervisor who wishes to read, alter,
> drop or replay the messages sent. The driver uses snp_issue_guest_request()
> to issue GHCB SNP_GUEST_REQUEST or SNP_EXT_GUEST_REQUEST NAE events to
> submit the request to PSP.
>
> The PSP requires that all communication should be encrypted using key
> specified through the platform_data.
>
> The userspace can use SNP_GET_REPORT ioctl() to query the guest
> attestation report.
>
> See SEV-SNP spec section Guest Messages for more details.
>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
> Documentation/virt/coco/sevguest.rst | 77 ++++
> drivers/virt/Kconfig | 3 +
> drivers/virt/Makefile | 1 +
> drivers/virt/coco/sevguest/Kconfig | 9 +
> drivers/virt/coco/sevguest/Makefile | 2 +
> drivers/virt/coco/sevguest/sevguest.c | 561 ++++++++++++++++++++++++++
> drivers/virt/coco/sevguest/sevguest.h | 98 +++++
> include/uapi/linux/sev-guest.h | 44 ++
> 8 files changed, 795 insertions(+)
> create mode 100644 Documentation/virt/coco/sevguest.rst
> create mode 100644 drivers/virt/coco/sevguest/Kconfig
> create mode 100644 drivers/virt/coco/sevguest/Makefile
> create mode 100644 drivers/virt/coco/sevguest/sevguest.c
> create mode 100644 drivers/virt/coco/sevguest/sevguest.h
> create mode 100644 include/uapi/linux/sev-guest.h
>

[...]

> +
> +static u8 *get_vmpck(int id, struct snp_secrets_page_layout *layout, u32 **seqno)
> +{
> + u8 *key = NULL;
> +
> + switch (id) {
> + case 0:
> + *seqno = &layout->os_area.msg_seqno_0;
> + key = layout->vmpck0;
> + break;
> + case 1:
> + *seqno = &layout->os_area.msg_seqno_1;
> + key = layout->vmpck1;
> + break;
> + case 2:
> + *seqno = &layout->os_area.msg_seqno_2;
> + key = layout->vmpck2;
> + break;
> + case 3:
> + *seqno = &layout->os_area.msg_seqno_3;
> + key = layout->vmpck3;
> + break;
> + default:
> + break;
> + }
> +
> + return NULL;

This should be 'return key', right?

-Dov

> +}
> +