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32fad281c0
This adds a new ioctl to enable userspace to control the size of the guest hashed page table (HPT) and to clear it out when resetting the guest. The KVM_PPC_ALLOCATE_HTAB ioctl is a VM ioctl and takes as its parameter a pointer to a u32 containing the desired order of the HPT (log base 2 of the size in bytes), which is updated on successful return to the actual order of the HPT which was allocated. There must be no vcpus running at the time of this ioctl. To enforce this, we now keep a count of the number of vcpus running in kvm->arch.vcpus_running. If the ioctl is called when a HPT has already been allocated, we don't reallocate the HPT but just clear it out. We first clear the kvm->arch.rma_setup_done flag, which has two effects: (a) since we hold the kvm->lock mutex, it will prevent any vcpus from starting to run until we're done, and (b) it means that the first vcpu to run after we're done will re-establish the VRMA if necessary. If userspace doesn't call this ioctl before running the first vcpu, the kernel will allocate a default-sized HPT at that point. We do it then rather than when creating the VM, as the code did previously, so that userspace has a chance to do the ioctl if it wants. When allocating the HPT, we can allocate either from the kernel page allocator, or from the preallocated pool. If userspace is asking for a different size from the preallocated HPTs, we first try to allocate using the kernel page allocator. Then we try to allocate from the preallocated pool, and then if that fails, we try allocating decreasing sizes from the kernel page allocator, down to the minimum size allowed (256kB). Note that the kernel page allocator limits allocations to 1 << CONFIG_FORCE_MAX_ZONEORDER pages, which by default corresponds to 16MB (on 64-bit powerpc, at least). Signed-off-by: Paul Mackerras <paulus@samba.org> [agraf: fix module compilation] Signed-off-by: Alexander Graf <agraf@suse.de>
234 lines
5.6 KiB
C
234 lines
5.6 KiB
C
/*
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* Copyright 2011 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License, version 2, as
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* published by the Free Software Foundation.
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*/
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#include <linux/kvm_host.h>
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#include <linux/preempt.h>
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#include <linux/export.h>
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#include <linux/sched.h>
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#include <linux/spinlock.h>
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#include <linux/bootmem.h>
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#include <linux/init.h>
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#include <asm/cputable.h>
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#include <asm/kvm_ppc.h>
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#include <asm/kvm_book3s.h>
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#define KVM_LINEAR_RMA 0
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#define KVM_LINEAR_HPT 1
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static void __init kvm_linear_init_one(ulong size, int count, int type);
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static struct kvmppc_linear_info *kvm_alloc_linear(int type);
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static void kvm_release_linear(struct kvmppc_linear_info *ri);
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int kvm_hpt_order = KVM_DEFAULT_HPT_ORDER;
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EXPORT_SYMBOL_GPL(kvm_hpt_order);
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/*************** RMA *************/
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/*
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* This maintains a list of RMAs (real mode areas) for KVM guests to use.
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* Each RMA has to be physically contiguous and of a size that the
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* hardware supports. PPC970 and POWER7 support 64MB, 128MB and 256MB,
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* and other larger sizes. Since we are unlikely to be allocate that
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* much physically contiguous memory after the system is up and running,
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* we preallocate a set of RMAs in early boot for KVM to use.
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*/
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static unsigned long kvm_rma_size = 64 << 20; /* 64MB */
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static unsigned long kvm_rma_count;
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/* Work out RMLS (real mode limit selector) field value for a given RMA size.
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Assumes POWER7 or PPC970. */
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static inline int lpcr_rmls(unsigned long rma_size)
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{
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switch (rma_size) {
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case 32ul << 20: /* 32 MB */
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if (cpu_has_feature(CPU_FTR_ARCH_206))
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return 8; /* only supported on POWER7 */
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return -1;
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case 64ul << 20: /* 64 MB */
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return 3;
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case 128ul << 20: /* 128 MB */
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return 7;
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case 256ul << 20: /* 256 MB */
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return 4;
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case 1ul << 30: /* 1 GB */
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return 2;
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case 16ul << 30: /* 16 GB */
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return 1;
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case 256ul << 30: /* 256 GB */
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return 0;
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default:
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return -1;
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}
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}
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static int __init early_parse_rma_size(char *p)
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{
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if (!p)
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return 1;
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kvm_rma_size = memparse(p, &p);
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return 0;
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}
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early_param("kvm_rma_size", early_parse_rma_size);
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static int __init early_parse_rma_count(char *p)
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{
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if (!p)
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return 1;
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kvm_rma_count = simple_strtoul(p, NULL, 0);
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return 0;
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}
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early_param("kvm_rma_count", early_parse_rma_count);
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struct kvmppc_linear_info *kvm_alloc_rma(void)
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{
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return kvm_alloc_linear(KVM_LINEAR_RMA);
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}
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EXPORT_SYMBOL_GPL(kvm_alloc_rma);
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void kvm_release_rma(struct kvmppc_linear_info *ri)
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{
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kvm_release_linear(ri);
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}
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EXPORT_SYMBOL_GPL(kvm_release_rma);
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/*************** HPT *************/
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/*
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* This maintains a list of big linear HPT tables that contain the GVA->HPA
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* memory mappings. If we don't reserve those early on, we might not be able
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* to get a big (usually 16MB) linear memory region from the kernel anymore.
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*/
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static unsigned long kvm_hpt_count;
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static int __init early_parse_hpt_count(char *p)
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{
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if (!p)
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return 1;
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kvm_hpt_count = simple_strtoul(p, NULL, 0);
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return 0;
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}
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early_param("kvm_hpt_count", early_parse_hpt_count);
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struct kvmppc_linear_info *kvm_alloc_hpt(void)
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{
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return kvm_alloc_linear(KVM_LINEAR_HPT);
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}
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EXPORT_SYMBOL_GPL(kvm_alloc_hpt);
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void kvm_release_hpt(struct kvmppc_linear_info *li)
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{
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kvm_release_linear(li);
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}
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EXPORT_SYMBOL_GPL(kvm_release_hpt);
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/*************** generic *************/
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static LIST_HEAD(free_linears);
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static DEFINE_SPINLOCK(linear_lock);
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static void __init kvm_linear_init_one(ulong size, int count, int type)
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{
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unsigned long i;
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unsigned long j, npages;
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void *linear;
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struct page *pg;
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const char *typestr;
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struct kvmppc_linear_info *linear_info;
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if (!count)
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return;
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typestr = (type == KVM_LINEAR_RMA) ? "RMA" : "HPT";
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npages = size >> PAGE_SHIFT;
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linear_info = alloc_bootmem(count * sizeof(struct kvmppc_linear_info));
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for (i = 0; i < count; ++i) {
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linear = alloc_bootmem_align(size, size);
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pr_info("Allocated KVM %s at %p (%ld MB)\n", typestr, linear,
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size >> 20);
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linear_info[i].base_virt = linear;
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linear_info[i].base_pfn = __pa(linear) >> PAGE_SHIFT;
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linear_info[i].npages = npages;
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linear_info[i].type = type;
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list_add_tail(&linear_info[i].list, &free_linears);
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atomic_set(&linear_info[i].use_count, 0);
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pg = pfn_to_page(linear_info[i].base_pfn);
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for (j = 0; j < npages; ++j) {
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atomic_inc(&pg->_count);
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++pg;
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}
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}
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}
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static struct kvmppc_linear_info *kvm_alloc_linear(int type)
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{
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struct kvmppc_linear_info *ri, *ret;
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ret = NULL;
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spin_lock(&linear_lock);
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list_for_each_entry(ri, &free_linears, list) {
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if (ri->type != type)
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continue;
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list_del(&ri->list);
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atomic_inc(&ri->use_count);
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memset(ri->base_virt, 0, ri->npages << PAGE_SHIFT);
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ret = ri;
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break;
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}
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spin_unlock(&linear_lock);
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return ret;
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}
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static void kvm_release_linear(struct kvmppc_linear_info *ri)
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{
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if (atomic_dec_and_test(&ri->use_count)) {
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spin_lock(&linear_lock);
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list_add_tail(&ri->list, &free_linears);
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spin_unlock(&linear_lock);
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}
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}
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/*
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* Called at boot time while the bootmem allocator is active,
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* to allocate contiguous physical memory for the hash page
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* tables for guests.
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*/
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void __init kvm_linear_init(void)
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{
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/* HPT */
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kvm_linear_init_one(1 << kvm_hpt_order, kvm_hpt_count, KVM_LINEAR_HPT);
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/* RMA */
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/* Only do this on PPC970 in HV mode */
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if (!cpu_has_feature(CPU_FTR_HVMODE) ||
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!cpu_has_feature(CPU_FTR_ARCH_201))
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return;
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if (!kvm_rma_size || !kvm_rma_count)
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return;
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/* Check that the requested size is one supported in hardware */
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if (lpcr_rmls(kvm_rma_size) < 0) {
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pr_err("RMA size of 0x%lx not supported\n", kvm_rma_size);
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return;
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}
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kvm_linear_init_one(kvm_rma_size, kvm_rma_count, KVM_LINEAR_RMA);
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}
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