Messages in this thread | | | Subject | Re: [PATCH v8 07/15] KVM: pfncache: include page offset in uhva and use it consistently | From | David Woodhouse <> | Date | Wed, 22 Nov 2023 09:12:18 +0000 |
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On Wed, 2023-11-22 at 16:54 +0800, Xu Yilun wrote: > > > @@ -259,13 +258,25 @@ static int __kvm_gpc_refresh(struct gfn_to_pfn_cache *gpc, gpa_t gpa, > > ret = -EFAULT; > > goto out; > > } > > + > > + hva_change = true; > > + } else { > > + /* > > + * No need to do any re-mapping if the only thing that has > > + * changed is the page offset. Just page align it to allow the > > + * new offset to be added in. > > I don't understand how the uhva('s offset) could be changed when both gpa and > slot are not changed. Maybe I have no knowledge of xen, but in later > patch you said your uhva would never change...
It doesn't change on a normal refresh with kvm_gpc_refresh(), which is just for revalidation after memslot changes or MMU invalidation.
But it can change if the gpc is being reinitialized with a new address (perhaps because the guest has made another hypercall to set the address, etc.)
That new address could happen to be in the *same* page as the previous one. In fact the xen_shinfo_test explicitly tests that case, IIRC.
And kvm_gpc_activate() also happens to use __kvm_gpc_refresh() internally. [unhandled content-type:application/pkcs7-signature] | |