Messages in this thread | | | Date | Fri, 29 Jul 2022 07:18:02 -0700 | Subject | Re: [PATCH v1 1/2] x86/sev: Use per-CPU PSC structure in prep for unaccepted memory support | From | Dave Hansen <> |
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On 7/29/22 07:01, Tom Lendacky wrote: > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index c05f0124c410..1f7f6205c4f6 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -104,6 +104,15 @@ struct sev_es_runtime_data { > * is currently unsupported in SEV-ES guests. > */ > unsigned long dr7; > + > + /* > + * Page State Change structure for use when accepting memory or when > + * changing page state. Interrupts are disabled when using the structure > + * but an NMI could still be raised, so use a flag to indicate when the > + * structure is in use and use the MSR protocol in these cases. > + */ > + struct snp_psc_desc psc_desc; > + bool psc_active; > };
This thing:
struct snp_psc_desc { struct psc_hdr hdr; struct psc_entry entries[VMGEXIT_PSC_MAX_ENTRY]; } __packed;
is 16k, right? Being per-cpu, this might eat up a MB or two of memory on a big server?
Considering that runtime acceptance is already single-threaded[1] *and* there's a fallback method, why not just have a single copy of this guarded by a single lock?
1. https://lore.kernel.org/all/20220614120231.48165-10-kirill.shutemov@linux.intel.com/
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