From 9973d54eeafcd1c3a2e89f0f59280c4c1e03e73b Mon Sep 17 00:00:00 2001 From: Scott Wood Date: Tue, 14 Jun 2011 18:34:39 -0500 Subject: [PATCH] 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 Signed-off-by: Alexander Graf --- arch/powerpc/kvm/e500_tlb.c | 103 ++++++++++++++++++++++++++++++++---- 1 file changed, 94 insertions(+), 9 deletions(-) diff --git a/arch/powerpc/kvm/e500_tlb.c b/arch/powerpc/kvm/e500_tlb.c index 0291c3cf5055..7f808c52e64a 100644 --- 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(¤t->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(¤t->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, -- 2.20.1