KVM: MMU: add SPTE_HOST_WRITEABLE flag to the shadow ptes
this flag notify that the host physical page we are pointing to from
the spte is write protected, and therefore we cant change its access
to be write unless we run get_user_pages(write = 1).
(this is needed for change_pte support in kvm)
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index d2fec9c..72558f8 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -273,9 +273,13 @@
if (mmu_notifier_retry(vcpu, vcpu->arch.update_pte.mmu_seq))
return;
kvm_get_pfn(pfn);
+ /*
+ * we call mmu_set_spte() with reset_host_protection = true beacuse that
+ * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
+ */
mmu_set_spte(vcpu, spte, page->role.access, pte_access, 0, 0,
gpte & PT_DIRTY_MASK, NULL, PT_PAGE_TABLE_LEVEL,
- gpte_to_gfn(gpte), pfn, true);
+ gpte_to_gfn(gpte), pfn, true, true);
}
/*
@@ -308,7 +312,7 @@
user_fault, write_fault,
gw->ptes[gw->level-1] & PT_DIRTY_MASK,
ptwrite, level,
- gw->gfn, pfn, false);
+ gw->gfn, pfn, false, true);
break;
}
@@ -558,6 +562,7 @@
static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
{
int i, offset, nr_present;
+ bool reset_host_protection;
offset = nr_present = 0;
@@ -595,9 +600,16 @@
nr_present++;
pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte);
+ if (!(sp->spt[i] & SPTE_HOST_WRITEABLE)) {
+ pte_access &= ~ACC_WRITE_MASK;
+ reset_host_protection = 0;
+ } else {
+ reset_host_protection = 1;
+ }
set_spte(vcpu, &sp->spt[i], pte_access, 0, 0,
is_dirty_gpte(gpte), PT_PAGE_TABLE_LEVEL, gfn,
- spte_to_pfn(sp->spt[i]), true, false);
+ spte_to_pfn(sp->spt[i]), true, false,
+ reset_host_protection);
}
return !nr_present;