Messages in this thread | | | Date | Tue, 31 Oct 2023 16:49:06 -0700 | Subject | Re: [PATCH v7 05/11] KVM: pfncache: allow a cache to be activated with a fixed (userspace) HVA | From | Sean Christopherson <> |
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On Mon, Oct 02, 2023, Paul Durrant wrote: > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h > index 6f4737d5046a..d49946ee7ae3 100644 > --- a/include/linux/kvm_types.h > +++ b/include/linux/kvm_types.h > @@ -64,7 +64,7 @@ struct gfn_to_hva_cache { > > struct gfn_to_pfn_cache { > u64 generation; > - gpa_t gpa; > + u64 addr;
Holy moly, we have unions for exactly this reason.
union { gpa_t gpa; unsigned long addr; };
But that's also weird and silly because it's basically the exact same thing as "uhva". If "uhva" stores the full address instead of the page-aligned address, then I don't see a need for unionizing the gpa and uhva.
kvm_xen_vcpu_get_attr() should darn well explicitly check that the gpc stores the correct type and not bleed ABI into the gfn_to_pfn_cache implementation.
If there's a true need for a union, the helpers should WARN.
> +unsigned long kvm_gpc_hva(struct gfn_to_pfn_cache *gpc) > +{ > + return !gpc->addr_is_gpa ? gpc->addr : 0;
'0' is a perfectly valid address. Yeah, practically speaking '0' can't be used these days, but we already have KVM_HVA_ERR_BAD. If y'all want to use the for the Xen ABI, then so be it. But the common helpers need to use a sane value.
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