| Date | Thu, 3 Feb 2022 07:50:35 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v9 20/43] x86/sev: Use SEV-SNP AP creation to start secondary CPUs |
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On Fri, Jan 28, 2022 at 11:17:41AM -0600, Brijesh Singh wrote: > @@ -822,6 +842,236 @@ void snp_set_memory_private(unsigned long vaddr, unsigned int npages) > pvalidate_pages(vaddr, npages, true); > } > > +static int snp_set_vmsa(void *va, bool vmsa) > +{ > + u64 attrs; > + > + /* > + * Running at VMPL0 allows the kernel to change the VMSA bit for a page > + * using the RMPADJUST instruction. However, for the instruction to > + * succeed it must target the permissions of a lesser privileged
"lesser privileged/higher number VMPL level"
so that it is perfectly clear what this means.
> + * VMPL level, so use VMPL1 (refer to the RMPADJUST instruction in the > + * AMD64 APM Volume 3). > + */ > + attrs = 1; > + if (vmsa) > + attrs |= RMPADJUST_VMSA_PAGE_BIT; > + > + return rmpadjust((unsigned long)va, RMP_PG_SIZE_4K, attrs); > +}
...
> +static int wakeup_cpu_via_vmgexit(int apic_id, unsigned long start_ip) > +{ > + struct sev_es_save_area *cur_vmsa, *vmsa; > + struct ghcb_state state; > + unsigned long flags; > + struct ghcb *ghcb; > + u8 sipi_vector; > + int cpu, ret; > + u64 cr4; > + > + /* > + * SNP-SNP AP creation requires that the hypervisor must support SEV-SNP ^^^^^^^
See what I mean? :-)
That marketing has brainwashed y'all.
> + * feature. The SEV-SNP feature check is already performed, so just check > + * for the AP_CREATION feature flag. > + */
Let's clean this one:
/* * The hypervisor SNP feature support check has happened earlier, just check * the AP_CREATION one here. */
> + if (!(sev_hv_features & GHCB_HV_FT_SNP_AP_CREATION)) > + return -EOPNOTSUPP; > + > + /* > + * Verify the desired start IP against the known trampoline start IP > + * to catch any future new trampolines that may be introduced that > + * would require a new protected guest entry point. > + */ > + if (WARN_ONCE(start_ip != real_mode_header->trampoline_start, > + "Unsupported SEV-SNP start_ip: %lx\n", start_ip)) > + return -EINVAL; > + > + /* Override start_ip with known protected guest start IP */ > + start_ip = real_mode_header->sev_es_trampoline_start;
Yah, I'd like to get rid of that ->sev_es_trampoline_start and use the normal ->trampoline_start. TDX is introducing a third one even and they're all mutually-exclusive u32 values.
...
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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