1 files changed, 684 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c
new file mode 100644
index 000000000..57af53a6a
--- /dev/null
+++ b/arch/powerpc/kvm/book3s_64_vio_hv.c
@@ -0,0 +1,684 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
+ * Copyright 2011 David Gibson, IBM Corporation <dwg@au1.ibm.com>
+ * Copyright 2016 Alexey Kardashevskiy, IBM Corporation <aik@au1.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kvm.h>
+#include <linux/kvm_host.h>
+#include <linux/highmem.h>
+#include <linux/gfp.h>
+#include <linux/slab.h>
+#include <linux/hugetlb.h>
+#include <linux/list.h>
+#include <linux/stringify.h>
+
+#include <asm/kvm_ppc.h>
+#include <asm/kvm_book3s.h>
+#include <asm/book3s/64/mmu-hash.h>
+#include <asm/mmu_context.h>
+#include <asm/hvcall.h>
+#include <asm/synch.h>
+#include <asm/ppc-opcode.h>
+#include <asm/udbg.h>
+#include <asm/iommu.h>
+#include <asm/tce.h>
+#include <asm/pte-walk.h>
+
+#ifdef CONFIG_BUG
+
+#define WARN_ON_ONCE_RM(condition)	({			\
+	static bool __section(".data.unlikely") __warned;	\
+	int __ret_warn_once = !!(condition);			\
+								\
+	if (unlikely(__ret_warn_once && !__warned)) {		\
+		__warned = true;				\
+		pr_err("WARN_ON_ONCE_RM: (%s) at %s:%u\n",	\
+				__stringify(condition),		\
+				__func__, __LINE__);		\
+		dump_stack();					\
+	}							\
+	unlikely(__ret_warn_once);				\
+})
+
+#else
+
+#define WARN_ON_ONCE_RM(condition) ({				\
+	int __ret_warn_on = !!(condition);			\
+	unlikely(__ret_warn_on);				\
+})
+
+#endif
+
+/*
+ * Finds a TCE table descriptor by LIOBN.
+ *
+ * WARNING: This will be called in real or virtual mode on HV KVM and virtual
+ *          mode on PR KVM
+ */
+struct kvmppc_spapr_tce_table *kvmppc_find_table(struct kvm *kvm,
+		unsigned long liobn)
+{
+	struct kvmppc_spapr_tce_table *stt;
+
+	list_for_each_entry_lockless(stt, &kvm->arch.spapr_tce_tables, list)
+		if (stt->liobn == liobn)
+			return stt;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(kvmppc_find_table);
+
+#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
+static long kvmppc_rm_tce_to_ua(struct kvm *kvm,
+				unsigned long tce, unsigned long *ua)
+{
+	unsigned long gfn = tce >> PAGE_SHIFT;
+	struct kvm_memory_slot *memslot;
+
+	memslot = search_memslots(kvm_memslots_raw(kvm), gfn);
+	if (!memslot)
+		return -EINVAL;
+
+	*ua = __gfn_to_hva_memslot(memslot, gfn) |
+		(tce & ~(PAGE_MASK | TCE_PCI_READ | TCE_PCI_WRITE));
+
+	return 0;
+}
+
+/*
+ * Validates TCE address.
+ * At the moment flags and page mask are validated.
+ * As the host kernel does not access those addresses (just puts them
+ * to the table and user space is supposed to process them), we can skip
+ * checking other things (such as TCE is a guest RAM address or the page
+ * was actually allocated).
+ */
+static long kvmppc_rm_tce_validate(struct kvmppc_spapr_tce_table *stt,
+		unsigned long tce)
+{
+	unsigned long gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
+	enum dma_data_direction dir = iommu_tce_direction(tce);
+	struct kvmppc_spapr_tce_iommu_table *stit;
+	unsigned long ua = 0;
+
+	/* Allow userspace to poison TCE table */
+	if (dir == DMA_NONE)
+		return H_SUCCESS;
+
+	if (iommu_tce_check_gpa(stt->page_shift, gpa))
+		return H_PARAMETER;
+
+	if (kvmppc_rm_tce_to_ua(stt->kvm, tce, &ua))
+		return H_TOO_HARD;
+
+	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
+		unsigned long hpa = 0;
+		struct mm_iommu_table_group_mem_t *mem;
+		long shift = stit->tbl->it_page_shift;
+
+		mem = mm_iommu_lookup_rm(stt->kvm->mm, ua, 1ULL << shift);
+		if (!mem)
+			return H_TOO_HARD;
+
+		if (mm_iommu_ua_to_hpa_rm(mem, ua, shift, &hpa))
+			return H_TOO_HARD;
+	}
+
+	return H_SUCCESS;
+}
+
+/* Note on the use of page_address() in real mode,
+ *
+ * It is safe to use page_address() in real mode on ppc64 because
+ * page_address() is always defined as lowmem_page_address()
+ * which returns __va(PFN_PHYS(page_to_pfn(page))) which is arithmetic
+ * operation and does not access page struct.
+ *
+ * Theoretically page_address() could be defined different
+ * but either WANT_PAGE_VIRTUAL or HASHED_PAGE_VIRTUAL
+ * would have to be enabled.
+ * WANT_PAGE_VIRTUAL is never enabled on ppc32/ppc64,
+ * HASHED_PAGE_VIRTUAL could be enabled for ppc32 only and only
+ * if CONFIG_HIGHMEM is defined. As CONFIG_SPARSEMEM_VMEMMAP
+ * is not expected to be enabled on ppc32, page_address()
+ * is safe for ppc32 as well.
+ *
+ * WARNING: This will be called in real-mode on HV KVM and virtual
+ *          mode on PR KVM
+ */
+static u64 *kvmppc_page_address(struct page *page)
+{
+#if defined(HASHED_PAGE_VIRTUAL) || defined(WANT_PAGE_VIRTUAL)
+#error TODO: fix to avoid page_address() here
+#endif
+	return (u64 *) page_address(page);
+}
+
+/*
+ * Handles TCE requests for emulated devices.
+ * Puts guest TCE values to the table and expects user space to convert them.
+ * Cannot fail so kvmppc_rm_tce_validate must be called before it.
+ */
+static void kvmppc_rm_tce_put(struct kvmppc_spapr_tce_table *stt,
+		unsigned long idx, unsigned long tce)
+{
+	struct page *page;
+	u64 *tbl;
+
+	idx -= stt->offset;
+	page = stt->pages[idx / TCES_PER_PAGE];
+	/*
+	 * kvmppc_rm_ioba_validate() allows pages not be allocated if TCE is
+	 * being cleared, otherwise it returns H_TOO_HARD and we skip this.
+	 */
+	if (!page) {
+		WARN_ON_ONCE_RM(tce != 0);
+		return;
+	}
+	tbl = kvmppc_page_address(page);
+
+	tbl[idx % TCES_PER_PAGE] = tce;
+}
+
+/*
+ * TCEs pages are allocated in kvmppc_rm_tce_put() which won't be able to do so
+ * in real mode.
+ * Check if kvmppc_rm_tce_put() can succeed in real mode, i.e. a TCEs page is
+ * allocated or not required (when clearing a tce entry).
+ */
+static long kvmppc_rm_ioba_validate(struct kvmppc_spapr_tce_table *stt,
+		unsigned long ioba, unsigned long npages, bool clearing)
+{
+	unsigned long i, idx, sttpage, sttpages;
+	unsigned long ret = kvmppc_ioba_validate(stt, ioba, npages);
+
+	if (ret)
+		return ret;
+	/*
+	 * clearing==true says kvmppc_rm_tce_put won't be allocating pages
+	 * for empty tces.
+	 */
+	if (clearing)
+		return H_SUCCESS;
+
+	idx = (ioba >> stt->page_shift) - stt->offset;
+	sttpage = idx / TCES_PER_PAGE;
+	sttpages = ALIGN(idx % TCES_PER_PAGE + npages, TCES_PER_PAGE) /
+			TCES_PER_PAGE;
+	for (i = sttpage; i < sttpage + sttpages; ++i)
+		if (!stt->pages[i])
+			return H_TOO_HARD;
+
+	return H_SUCCESS;
+}
+
+static long iommu_tce_xchg_no_kill_rm(struct mm_struct *mm,
+		struct iommu_table *tbl,
+		unsigned long entry, unsigned long *hpa,
+		enum dma_data_direction *direction)
+{
+	long ret;
+
+	ret = tbl->it_ops->xchg_no_kill(tbl, entry, hpa, direction, true);
+
+	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
+				(*direction == DMA_BIDIRECTIONAL))) {
+		__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY_RO(tbl, entry);
+		/*
+		 * kvmppc_rm_tce_iommu_do_map() updates the UA cache after
+		 * calling this so we still get here a valid UA.
+		 */
+		if (pua && *pua)
+			mm_iommu_ua_mark_dirty_rm(mm, be64_to_cpu(*pua));
+	}
+
+	return ret;
+}
+
+static void iommu_tce_kill_rm(struct iommu_table *tbl,
+		unsigned long entry, unsigned long pages)
+{
+	if (tbl->it_ops->tce_kill)
+		tbl->it_ops->tce_kill(tbl, entry, pages, true);
+}
+
+static void kvmppc_rm_clear_tce(struct kvm *kvm, struct kvmppc_spapr_tce_table *stt,
+		struct iommu_table *tbl, unsigned long entry)
+{
+	unsigned long i;
+	unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
+	unsigned long io_entry = entry << (stt->page_shift - tbl->it_page_shift);
+
+	for (i = 0; i < subpages; ++i) {
+		unsigned long hpa = 0;
+		enum dma_data_direction dir = DMA_NONE;
+
+		iommu_tce_xchg_no_kill_rm(kvm->mm, tbl, io_entry + i, &hpa, &dir);
+	}
+}
+
+static long kvmppc_rm_tce_iommu_mapped_dec(struct kvm *kvm,
+		struct iommu_table *tbl, unsigned long entry)
+{
+	struct mm_iommu_table_group_mem_t *mem = NULL;
+	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
+	__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY_RO(tbl, entry);
+
+	if (!pua)
+		/* it_userspace allocation might be delayed */
+		return H_TOO_HARD;
+
+	mem = mm_iommu_lookup_rm(kvm->mm, be64_to_cpu(*pua), pgsize);
+	if (!mem)
+		return H_TOO_HARD;
+
+	mm_iommu_mapped_dec(mem);
+
+	*pua = cpu_to_be64(0);
+
+	return H_SUCCESS;
+}
+
+static long kvmppc_rm_tce_iommu_do_unmap(struct kvm *kvm,
+		struct iommu_table *tbl, unsigned long entry)
+{
+	enum dma_data_direction dir = DMA_NONE;
+	unsigned long hpa = 0;
+	long ret;
+
+	if (iommu_tce_xchg_no_kill_rm(kvm->mm, tbl, entry, &hpa, &dir))
+		/*
+		 * real mode xchg can fail if struct page crosses
+		 * a page boundary
+		 */
+		return H_TOO_HARD;
+
+	if (dir == DMA_NONE)
+		return H_SUCCESS;
+
+	ret = kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
+	if (ret)
+		iommu_tce_xchg_no_kill_rm(kvm->mm, tbl, entry, &hpa, &dir);
+
+	return ret;
+}
+
+static long kvmppc_rm_tce_iommu_unmap(struct kvm *kvm,
+		struct kvmppc_spapr_tce_table *stt, struct iommu_table *tbl,
+		unsigned long entry)
+{
+	unsigned long i, ret = H_SUCCESS;
+	unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
+	unsigned long io_entry = entry * subpages;
+
+	for (i = 0; i < subpages; ++i) {
+		ret = kvmppc_rm_tce_iommu_do_unmap(kvm, tbl, io_entry + i);
+		if (ret != H_SUCCESS)
+			break;
+	}
+
+	iommu_tce_kill_rm(tbl, io_entry, subpages);
+
+	return ret;
+}
+
+static long kvmppc_rm_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
+		unsigned long entry, unsigned long ua,
+		enum dma_data_direction dir)
+{
+	long ret;
+	unsigned long hpa = 0;
+	__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY_RO(tbl, entry);
+	struct mm_iommu_table_group_mem_t *mem;
+
+	if (!pua)
+		/* it_userspace allocation might be delayed */
+		return H_TOO_HARD;
+
+	mem = mm_iommu_lookup_rm(kvm->mm, ua, 1ULL << tbl->it_page_shift);
+	if (!mem)
+		return H_TOO_HARD;
+
+	if (WARN_ON_ONCE_RM(mm_iommu_ua_to_hpa_rm(mem, ua, tbl->it_page_shift,
+			&hpa)))
+		return H_TOO_HARD;
+
+	if (WARN_ON_ONCE_RM(mm_iommu_mapped_inc(mem)))
+		return H_TOO_HARD;
+
+	ret = iommu_tce_xchg_no_kill_rm(kvm->mm, tbl, entry, &hpa, &dir);
+	if (ret) {
+		mm_iommu_mapped_dec(mem);
+		/*
+		 * real mode xchg can fail if struct page crosses
+		 * a page boundary
+		 */
+		return H_TOO_HARD;
+	}
+
+	if (dir != DMA_NONE)
+		kvmppc_rm_tce_iommu_mapped_dec(kvm, tbl, entry);
+
+	*pua = cpu_to_be64(ua);
+
+	return 0;
+}
+
+static long kvmppc_rm_tce_iommu_map(struct kvm *kvm,
+		struct kvmppc_spapr_tce_table *stt, struct iommu_table *tbl,
+		unsigned long entry, unsigned long ua,
+		enum dma_data_direction dir)
+{
+	unsigned long i, pgoff, ret = H_SUCCESS;
+	unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
+	unsigned long io_entry = entry * subpages;
+
+	for (i = 0, pgoff = 0; i < subpages;
+			++i, pgoff += IOMMU_PAGE_SIZE(tbl)) {
+
+		ret = kvmppc_rm_tce_iommu_do_map(kvm, tbl,
+				io_entry + i, ua + pgoff, dir);
+		if (ret != H_SUCCESS)
+			break;
+	}
+
+	iommu_tce_kill_rm(tbl, io_entry, subpages);
+
+	return ret;
+}
+
+long kvmppc_rm_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
+		unsigned long ioba, unsigned long tce)
+{
+	struct kvmppc_spapr_tce_table *stt;
+	long ret;
+	struct kvmppc_spapr_tce_iommu_table *stit;
+	unsigned long entry, ua = 0;
+	enum dma_data_direction dir;
+
+	/* udbg_printf("H_PUT_TCE(): liobn=0x%lx ioba=0x%lx, tce=0x%lx\n", */
+	/* 	    liobn, ioba, tce); */
+
+	/* For radix, we might be in virtual mode, so punt */
+	if (kvm_is_radix(vcpu->kvm))
+		return H_TOO_HARD;
+
+	stt = kvmppc_find_table(vcpu->kvm, liobn);
+	if (!stt)
+		return H_TOO_HARD;
+
+	ret = kvmppc_rm_ioba_validate(stt, ioba, 1, tce == 0);
+	if (ret != H_SUCCESS)
+		return ret;
+
+	ret = kvmppc_rm_tce_validate(stt, tce);
+	if (ret != H_SUCCESS)
+		return ret;
+
+	dir = iommu_tce_direction(tce);
+	if ((dir != DMA_NONE) && kvmppc_rm_tce_to_ua(vcpu->kvm, tce, &ua))
+		return H_PARAMETER;
+
+	entry = ioba >> stt->page_shift;
+
+	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
+		if (dir == DMA_NONE)
+			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm, stt,
+					stit->tbl, entry);
+		else
+			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt,
+					stit->tbl, entry, ua, dir);
+
+		if (ret != H_SUCCESS) {
+			kvmppc_rm_clear_tce(vcpu->kvm, stt, stit->tbl, entry);
+			return ret;
+		}
+	}
+
+	kvmppc_rm_tce_put(stt, entry, tce);
+
+	return H_SUCCESS;
+}
+
+static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, unsigned long mmu_seq,
+				unsigned long ua, unsigned long *phpa)
+{
+	pte_t *ptep, pte;
+	unsigned shift = 0;
+
+	/*
+	 * Called in real mode with MSR_EE = 0. We are safe here.
+	 * It is ok to do the lookup with arch.pgdir here, because
+	 * we are doing this on secondary cpus and current task there
+	 * is not the hypervisor. Also this is safe against THP in the
+	 * host, because an IPI to primary thread will wait for the secondary
+	 * to exit which will agains result in the below page table walk
+	 * to finish.
+	 */
+	/* an rmap lock won't make it safe. because that just ensure hash
+	 * page table entries are removed with rmap lock held. After that
+	 * mmu notifier returns and we go ahead and removing ptes from Qemu page table.
+	 */
+	ptep = find_kvm_host_pte(vcpu->kvm, mmu_seq, ua, &shift);
+	if (!ptep)
+		return -ENXIO;
+
+	pte = READ_ONCE(*ptep);
+	if (!pte_present(pte))
+		return -ENXIO;
+
+	if (!shift)
+		shift = PAGE_SHIFT;
+
+	/* Avoid handling anything potentially complicated in realmode */
+	if (shift > PAGE_SHIFT)
+		return -EAGAIN;
+
+	if (!pte_young(pte))
+		return -EAGAIN;
+
+	*phpa = (pte_pfn(pte) << PAGE_SHIFT) | (ua & ((1ULL << shift) - 1)) |
+			(ua & ~PAGE_MASK);
+
+	return 0;
+}
+
+long kvmppc_rm_h_put_tce_indirect(struct kvm_vcpu *vcpu,
+		unsigned long liobn, unsigned long ioba,
+		unsigned long tce_list,	unsigned long npages)
+{
+	struct kvm *kvm = vcpu->kvm;
+	struct kvmppc_spapr_tce_table *stt;
+	long i, ret = H_SUCCESS;
+	unsigned long tces, entry, ua = 0;
+	unsigned long mmu_seq;
+	bool prereg = false;
+	struct kvmppc_spapr_tce_iommu_table *stit;
+
+	/* For radix, we might be in virtual mode, so punt */
+	if (kvm_is_radix(vcpu->kvm))
+		return H_TOO_HARD;
+
+	/*
+	 * used to check for invalidations in progress
+	 */
+	mmu_seq = kvm->mmu_notifier_seq;
+	smp_rmb();
+
+	stt = kvmppc_find_table(vcpu->kvm, liobn);
+	if (!stt)
+		return H_TOO_HARD;
+
+	entry = ioba >> stt->page_shift;
+	/*
+	 * The spec says that the maximum size of the list is 512 TCEs
+	 * so the whole table addressed resides in 4K page
+	 */
+	if (npages > 512)
+		return H_PARAMETER;
+
+	if (tce_list & (SZ_4K - 1))
+		return H_PARAMETER;
+
+	ret = kvmppc_rm_ioba_validate(stt, ioba, npages, false);
+	if (ret != H_SUCCESS)
+		return ret;
+
+	if (mm_iommu_preregistered(vcpu->kvm->mm)) {
+		/*
+		 * We get here if guest memory was pre-registered which
+		 * is normally VFIO case and gpa->hpa translation does not
+		 * depend on hpt.
+		 */
+		struct mm_iommu_table_group_mem_t *mem;
+
+		if (kvmppc_rm_tce_to_ua(vcpu->kvm, tce_list, &ua))
+			return H_TOO_HARD;
+
+		mem = mm_iommu_lookup_rm(vcpu->kvm->mm, ua, IOMMU_PAGE_SIZE_4K);
+		if (mem)
+			prereg = mm_iommu_ua_to_hpa_rm(mem, ua,
+					IOMMU_PAGE_SHIFT_4K, &tces) == 0;
+	}
+
+	if (!prereg) {
+		/*
+		 * This is usually a case of a guest with emulated devices only
+		 * when TCE list is not in preregistered memory.
+		 * We do not require memory to be preregistered in this case
+		 * so lock rmap and do __find_linux_pte_or_hugepte().
+		 */
+		if (kvmppc_rm_tce_to_ua(vcpu->kvm, tce_list, &ua))
+			return H_TOO_HARD;
+
+		arch_spin_lock(&kvm->mmu_lock.rlock.raw_lock);
+		if (kvmppc_rm_ua_to_hpa(vcpu, mmu_seq, ua, &tces)) {
+			ret = H_TOO_HARD;
+			goto unlock_exit;
+		}
+	}
+
+	for (i = 0; i < npages; ++i) {
+		unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
+
+		ret = kvmppc_rm_tce_validate(stt, tce);
+		if (ret != H_SUCCESS)
+			goto unlock_exit;
+	}
+
+	for (i = 0; i < npages; ++i) {
+		unsigned long tce = be64_to_cpu(((u64 *)tces)[i]);
+
+		ua = 0;
+		if (kvmppc_rm_tce_to_ua(vcpu->kvm, tce, &ua)) {
+			ret = H_PARAMETER;
+			goto unlock_exit;
+		}
+
+		list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
+			ret = kvmppc_rm_tce_iommu_map(vcpu->kvm, stt,
+					stit->tbl, entry + i, ua,
+					iommu_tce_direction(tce));
+
+			if (ret != H_SUCCESS) {
+				kvmppc_rm_clear_tce(vcpu->kvm, stt, stit->tbl,
+						entry + i);
+				goto unlock_exit;
+			}
+		}
+
+		kvmppc_rm_tce_put(stt, entry + i, tce);
+	}
+
+unlock_exit:
+	if (!prereg)
+		arch_spin_unlock(&kvm->mmu_lock.rlock.raw_lock);
+	return ret;
+}
+
+long kvmppc_rm_h_stuff_tce(struct kvm_vcpu *vcpu,
+		unsigned long liobn, unsigned long ioba,
+		unsigned long tce_value, unsigned long npages)
+{
+	struct kvmppc_spapr_tce_table *stt;
+	long i, ret;
+	struct kvmppc_spapr_tce_iommu_table *stit;
+
+	/* For radix, we might be in virtual mode, so punt */
+	if (kvm_is_radix(vcpu->kvm))
+		return H_TOO_HARD;
+
+	stt = kvmppc_find_table(vcpu->kvm, liobn);
+	if (!stt)
+		return H_TOO_HARD;
+
+	ret = kvmppc_rm_ioba_validate(stt, ioba, npages, tce_value == 0);
+	if (ret != H_SUCCESS)
+		return ret;
+
+	/* Check permission bits only to allow userspace poison TCE for debug */
+	if (tce_value & (TCE_PCI_WRITE | TCE_PCI_READ))
+		return H_PARAMETER;
+
+	list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
+		unsigned long entry = ioba >> stt->page_shift;
+
+		for (i = 0; i < npages; ++i) {
+			ret = kvmppc_rm_tce_iommu_unmap(vcpu->kvm, stt,
+					stit->tbl, entry + i);
+
+			if (ret == H_SUCCESS)
+				continue;
+
+			if (ret == H_TOO_HARD)
+				return ret;
+
+			WARN_ON_ONCE_RM(1);
+			kvmppc_rm_clear_tce(vcpu->kvm, stt, stit->tbl, entry + i);
+		}
+	}
+
+	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
+		kvmppc_rm_tce_put(stt, ioba >> stt->page_shift, tce_value);
+
+	return ret;
+}
+
+/* This can be called in either virtual mode or real mode */
+long kvmppc_h_get_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
+		      unsigned long ioba)
+{
+	struct kvmppc_spapr_tce_table *stt;
+	long ret;
+	unsigned long idx;
+	struct page *page;
+	u64 *tbl;
+
+	stt = kvmppc_find_table(vcpu->kvm, liobn);
+	if (!stt)
+		return H_TOO_HARD;
+
+	ret = kvmppc_ioba_validate(stt, ioba, 1);
+	if (ret != H_SUCCESS)
+		return ret;
+
+	idx = (ioba >> stt->page_shift) - stt->offset;
+	page = stt->pages[idx / TCES_PER_PAGE];
+	if (!page) {
+		vcpu->arch.regs.gpr[4] = 0;
+		return H_SUCCESS;
+	}
+	tbl = (u64 *)page_address(page);
+
+	vcpu->arch.regs.gpr[4] = tbl[idx % TCES_PER_PAGE];
+
+	return H_SUCCESS;
+}
+EXPORT_SYMBOL_GPL(kvmppc_h_get_tce);
+
+#endif /* KVM_BOOK3S_HV_POSSIBLE */