Messages in this thread | | | Subject | Re: [PATCH v2 3/4] KVM: SVM: move sev_bind_asid to psp | From | Brijesh Singh <> | Date | Thu, 9 Sep 2021 17:25:25 -0500 |
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On 9/9/21 4:18 PM, Mingwei Zhang wrote: >>> Most of the address field in the "struct sev_data_*" are physical >>> addressess. The userspace will not be able to populate those fields. >> >> Yeah, that's my biggest hesitation to using struct sev_data_* in the API, it's >> both confusing and gross. But it's also why I think these helpers belong in the >> PSP driver, KVM should not need to know the "on-the-wire" format for communicating >> with the PSP. >> > > Did a simple checking for all struct sev_data_* fields defined in psp-sev.h:
thank you for compiling the list, let me add few more at the end of your list (they are part of spec but PSP/KVM does not have support for it).
I am also adding SNP specific so that we get a full picture.
> > The average argument is roughly 4 (103/27), detailed data appended at > last. In addition, I believe the most used commands would be the > following? > > #data structure name: number of meaningful fields > sev_data_launch_start: 6 > sev_data_activate: 2 > sev_data_decommission: 1 > sev_data_receive_update_data: 7 > sev_data_send_update_vmsa: 7 > sev_data_launch_measure: 3 > sev_data_launch_finish: 1 > sev_data_deactivate: 1 >
Once the page copy, and swap in/out is implemented then it will also be frequently used.
sev_data_copy: 4 sev_swap_out: 12 sev_swap_in: 7
snp_data_gctx_create: 1 snp_data_activate: 2 snp_data_deactivate: 2 snp_data_decommission: 1 snp_data_launch_start: 6 snp_data_launch_update: 8 snp_data_launch_finish: 6 snp_data_page_move: 4 snp_data_page_swap_out: 8 snp_data_page_swap_in: 8 snp_data_page_reclaim: 2 snp_guest_request: 3 snp_guest_request_ext: 5
> For the above frequently-used command set, the average argument length > is also around 3-4 (28/8) on average, 2.5 as the median. >
It averages around 4-5 (51/11) without snp. The good news is with snp the avg is still 4-5 (107/24).
Additionally, we also need to pass the sev->fd in each of these functions, which will increase avg to 5-6.
> So, from that perspective, I think we should just remove those > sev_data data structures in KVM, since it is more clear to read each > argument. >
I believe once we are done with it, will have 5 functions that will need >=8 arguments. I don't know if its acceptable.
> In addition, having to construct each sev_data_* structure in KVM code > is also a pain and consumes a lot of irrelevant lines as well. >
Maybe I am missing something, aren't those lines will be moved from KVM to PSP driver?
I am in full support for restructuring, but lets look at full set of PSP APIs before making the final decision.
thanks
> #data structure name: number of meaningful fields > sev_data_deactivate: 1 > sev_data_decommission: 1 > sev_data_launch_finish: 1 > sev_data_receive_finish: 1 > sev_data_send_cancel: 1 > sev_data_send_finish: 1 > sev_data_activate: 2 > sev_data_download_firmware: 2 > sev_data_get_id: 2 > sev_data_pek_csr: 2 > sev_data_init: 3 > sev_data_launch_measure: 3 > sev_data_launch_update_data: 3 > sev_data_launch_update_vmsa: 3 > sev_data_attestation_report: 4 > sev_data_dbg: 4 > sev_data_guest_status: 4 > sev_data_pdh_cert_export: 4 > sev_data_pek_cert_import: 4 > sev_data_launch_start: 6 > sev_data_receive_start: 6 > sev_data_launch_secret: 7 > sev_data_receive_update_data: 7 > sev_data_receive_update_vmsa: 7 > sev_data_send_update_data: 7 > sev_data_send_update_vmsa: 7 > sev_data_send_start: 10 >
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