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

[Dov Murik]

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@xxxxxxx>
> ---
>  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

> +}
> +