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Commit 9973d54e authored by Scott Wood's avatar Scott Wood Committed by Avi Kivity
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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: default avatarScott Wood <scottwood@freescale.com>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
parent 59c1f4e3

arch/powerpc/kvm/e500_tlb.c

+94 −9
Original line number Diff line number Diff line
@@ -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.

	 */

	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.

			 */

	pfn = gfn_to_pfn(vcpu_e500->vcpu.kvm, gfn);

			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,