{
struct domain *d = v->domain;
- /* Linear pagetables in PV guests
- * ------------------------------
- *
- * Guest linear pagetables, which map the guest pages, are at
- * LINEAR_PT_VIRT_START. Shadow linear pagetables, which map the
- * shadows, are at SH_LINEAR_PT_VIRT_START. Most of the time these
- * are set up at shadow creation time, but (of course!) the PAE case
- * is subtler. Normal linear mappings are made by having an entry
- * in the top-level table that points to itself (shadow linear) or
- * to the guest top-level table (guest linear). For PAE, to set up
- * a linear map requires us to copy the four top-level entries into
- * level-2 entries. That means that every time we change a PAE l3e,
- * we need to reflect the change into the copy.
- *
+ /*
* Linear pagetables in HVM guests
* -------------------------------
*
*/
/* Don't try to update the monitor table if it doesn't exist */
- if ( shadow_mode_external(d)
- && pagetable_get_pfn(v->arch.monitor_table) == 0 )
+ if ( !shadow_mode_external(d) ||
+ pagetable_get_pfn(v->arch.monitor_table) == 0 )
return;
#if SHADOW_PAGING_LEVELS == 4
- /* For PV, one l4e points at the guest l4, one points at the shadow
- * l4. No maintenance required.
- * For HVM, just need to update the l4e that points to the shadow l4. */
+ /* For HVM, just need to update the l4e that points to the shadow l4. */
- if ( shadow_mode_external(d) )
+ /* Use the linear map if we can; otherwise make a new mapping */
+ if ( v == current )
{
- /* Use the linear map if we can; otherwise make a new mapping */
- if ( v == current )
- {
- __linear_l4_table[l4_linear_offset(SH_LINEAR_PT_VIRT_START)] =
- l4e_from_pfn(pagetable_get_pfn(v->arch.shadow_table[0]),
- __PAGE_HYPERVISOR_RW);
- }
- else
- {
- l4_pgentry_t *ml4e;
- ml4e = map_domain_page(pagetable_get_mfn(v->arch.monitor_table));
- ml4e[l4_table_offset(SH_LINEAR_PT_VIRT_START)] =
- l4e_from_pfn(pagetable_get_pfn(v->arch.shadow_table[0]),
- __PAGE_HYPERVISOR_RW);
- unmap_domain_page(ml4e);
- }
+ __linear_l4_table[l4_linear_offset(SH_LINEAR_PT_VIRT_START)] =
+ l4e_from_pfn(pagetable_get_pfn(v->arch.shadow_table[0]),
+ __PAGE_HYPERVISOR_RW);
+ }
+ else
+ {
+ l4_pgentry_t *ml4e;
+
+ ml4e = map_domain_page(pagetable_get_mfn(v->arch.monitor_table));
+ ml4e[l4_table_offset(SH_LINEAR_PT_VIRT_START)] =
+ l4e_from_pfn(pagetable_get_pfn(v->arch.shadow_table[0]),
+ __PAGE_HYPERVISOR_RW);
+ unmap_domain_page(ml4e);
}
#elif SHADOW_PAGING_LEVELS == 3
* the shadows.
*/
- ASSERT(shadow_mode_external(d));
{
/* Install copies of the shadow l3es into the monitor l2 table
* that maps SH_LINEAR_PT_VIRT_START. */
#error this should not happen
#endif
- if ( shadow_mode_external(d) )
- {
- /*
- * Having modified the linear pagetable mapping, flush local host TLBs.
- * This was not needed when vmenter/vmexit always had the side effect
- * of flushing host TLBs but, with ASIDs, it is possible to finish
- * this CR3 update, vmenter the guest, vmexit due to a page fault,
- * without an intervening host TLB flush. Then the page fault code
- * could use the linear pagetable to read a top-level shadow page
- * table entry. But, without this change, it would fetch the wrong
- * value due to a stale TLB.
- */
- flush_tlb_local();
- }
+ /*
+ * Having modified the linear pagetable mapping, flush local host TLBs.
+ * This was not needed when vmenter/vmexit always had the side effect of
+ * flushing host TLBs but, with ASIDs, it is possible to finish this CR3
+ * update, vmenter the guest, vmexit due to a page fault, without an
+ * intervening host TLB flush. Then the page fault code could use the
+ * linear pagetable to read a top-level shadow page table entry. But,
+ * without this change, it would fetch the wrong value due to a stale TLB.
+ */
+ flush_tlb_local();
}