KVM: PPC: e500: Support large page mappings of PFNMAP vmas.

This allows large pages to be used on guest mappings backed by things like
/dev/mem, resulting in a significant speedup when guest memory
is mapped this way (it's useful for directly-assigned MMIO, too).

This is not a substitute for hugetlbfs integration, but is useful for
configurations where devices are directly assigned on chips without an
IOMMU -- in these cases, we need guest physical and true physical to
match, and be contiguous, so static reservation and mapping via /dev/mem
is the most straightforward way to set things up.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/arch/powerpc/kvm/e500_tlb.c b/arch/powerpc/kvm/e500_tlb.c
index 0291c3cf5055b908a66072cc1fa0cc98a559651d..7f808c52e64ab936660e1e50f98ff2291a0241f2 100644 (file)
--- a/arch/powerpc/kvm/e500_tlb.c
+++ b/arch/powerpc/kvm/e500_tlb.c
@@ -270,28 +270,113 @@ static inline void kvmppc_e500_deliver_tlb_miss(struct kvm_vcpu *vcpu,
 static inline void kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500,
        u64 gvaddr, gfn_t gfn, struct tlbe *gtlbe, int tlbsel, int esel)
 {
+       struct kvm_memory_slot *slot;
        struct tlbe *stlbe;
-       unsigned long pfn;
+       unsigned long pfn, hva;
+       int pfnmap = 0;
+       int tsize = BOOK3E_PAGESZ_4K;
 
        stlbe = &vcpu_e500->shadow_tlb[tlbsel][esel];
 
        /*
         * Translate guest physical to true physical, acquiring
         * a page reference if it is normal, non-reserved memory.
+        *
+        * gfn_to_memslot() must succeed because otherwise we wouldn't
+        * have gotten this far.  Eventually we should just pass the slot
+        * pointer through from the first lookup.
         */
-       pfn = gfn_to_pfn(vcpu_e500->vcpu.kvm, gfn);
-       if (is_error_pfn(pfn)) {
-               printk(KERN_ERR "Couldn't get real page for gfn %lx!\n",
-                               (long)gfn);
-               kvm_release_pfn_clean(pfn);
-               return;
+       slot = gfn_to_memslot(vcpu_e500->vcpu.kvm, gfn);
+       hva = gfn_to_hva_memslot(slot, gfn);
+
+       if (tlbsel == 1) {
+               struct vm_area_struct *vma;
+               down_read(&current->mm->mmap_sem);
+
+               vma = find_vma(current->mm, hva);
+               if (vma && hva >= vma->vm_start &&
+                   (vma->vm_flags & VM_PFNMAP)) {
+                       /*
+                        * This VMA is a physically contiguous region (e.g.
+                        * /dev/mem) that bypasses normal Linux page
+                        * management.  Find the overlap between the
+                        * vma and the memslot.
+                        */
+
+                       unsigned long start, end;
+                       unsigned long slot_start, slot_end;
+
+                       pfnmap = 1;
+
+                       start = vma->vm_pgoff;
+                       end = start +
+                             ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT);
+
+                       pfn = start + ((hva - vma->vm_start) >> PAGE_SHIFT);
+
+                       slot_start = pfn - (gfn - slot->base_gfn);
+                       slot_end = slot_start + slot->npages;
+
+                       if (start < slot_start)
+                               start = slot_start;
+                       if (end > slot_end)
+                               end = slot_end;
+
+                       tsize = (gtlbe->mas1 & MAS1_TSIZE_MASK) >>
+                               MAS1_TSIZE_SHIFT;
+
+                       /*
+                        * e500 doesn't implement the lowest tsize bit,
+                        * or 1K pages.
+                        */
+                       tsize = max(BOOK3E_PAGESZ_4K, tsize & ~1);
+
+                       /*
+                        * Now find the largest tsize (up to what the guest
+                        * requested) that will cover gfn, stay within the
+                        * range, and for which gfn and pfn are mutually
+                        * aligned.
+                        */
+
+                       for (; tsize > BOOK3E_PAGESZ_4K; tsize -= 2) {
+                               unsigned long gfn_start, gfn_end, tsize_pages;
+                               tsize_pages = 1 << (tsize - 2);
+
+                               gfn_start = gfn & ~(tsize_pages - 1);
+                               gfn_end = gfn_start + tsize_pages;
+
+                               if (gfn_start + pfn - gfn < start)
+                                       continue;
+                               if (gfn_end + pfn - gfn > end)
+                                       continue;
+                               if ((gfn & (tsize_pages - 1)) !=
+                                   (pfn & (tsize_pages - 1)))
+                                       continue;
+
+                               gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
+                               pfn &= ~(tsize_pages - 1);
+                               break;
+                       }
+               }
+
+               up_read(&current->mm->mmap_sem);
+       }
+
+       if (likely(!pfnmap)) {
+               pfn = gfn_to_pfn_memslot(vcpu_e500->vcpu.kvm, slot, gfn);
+               if (is_error_pfn(pfn)) {
+                       printk(KERN_ERR "Couldn't get real page for gfn %lx!\n",
+                                       (long)gfn);
+                       kvm_release_pfn_clean(pfn);
+                       return;
+               }
        }
 
        /* Drop reference to old page. */
        kvmppc_e500_shadow_release(vcpu_e500, tlbsel, esel);
 
-       /* Force TS=1 IPROT=0 TSIZE=4KB for all guest mappings. */
-       stlbe->mas1 = MAS1_TSIZE(BOOK3E_PAGESZ_4K)
+       /* Force TS=1 IPROT=0 for all guest mappings. */
+       stlbe->mas1 = MAS1_TSIZE(tsize)
                | MAS1_TID(get_tlb_tid(gtlbe)) | MAS1_TS | MAS1_VALID;
        stlbe->mas2 = (gvaddr & MAS2_EPN)
                | e500_shadow_mas2_attrib(gtlbe->mas2,