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https://github.com/torvalds/linux
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2d4f567103
We will soon require more sophisticated methods to replace single instructions with multiple instructions. We do that by branching to a memory region where we write replacement code for the instruction to. This region needs to be within 32 MB of the patched instruction though, because that's the furthest we can jump with immediate branches. So we keep 1MB of free space around in bss. After we're done initing we can just tell the mm system that the unused pages are free, but until then we have enough space to fit all our code in. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
326 lines
8.1 KiB
C
326 lines
8.1 KiB
C
/*
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* Copyright (C) 2010 SUSE Linux Products GmbH. All rights reserved.
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*
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* Authors:
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* Alexander Graf <agraf@suse.de>
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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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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*/
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#include <linux/kvm_host.h>
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#include <linux/init.h>
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#include <linux/kvm_para.h>
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#include <linux/slab.h>
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#include <linux/of.h>
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#include <asm/reg.h>
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#include <asm/kvm_ppc.h>
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#include <asm/sections.h>
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#include <asm/cacheflush.h>
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#include <asm/disassemble.h>
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#define KVM_MAGIC_PAGE (-4096L)
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#define magic_var(x) KVM_MAGIC_PAGE + offsetof(struct kvm_vcpu_arch_shared, x)
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#define KVM_INST_LWZ 0x80000000
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#define KVM_INST_STW 0x90000000
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#define KVM_INST_LD 0xe8000000
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#define KVM_INST_STD 0xf8000000
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#define KVM_INST_NOP 0x60000000
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#define KVM_INST_B 0x48000000
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#define KVM_INST_B_MASK 0x03ffffff
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#define KVM_INST_B_MAX 0x01ffffff
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#define KVM_MASK_RT 0x03e00000
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#define KVM_INST_MFMSR 0x7c0000a6
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#define KVM_INST_MFSPR_SPRG0 0x7c1042a6
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#define KVM_INST_MFSPR_SPRG1 0x7c1142a6
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#define KVM_INST_MFSPR_SPRG2 0x7c1242a6
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#define KVM_INST_MFSPR_SPRG3 0x7c1342a6
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#define KVM_INST_MFSPR_SRR0 0x7c1a02a6
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#define KVM_INST_MFSPR_SRR1 0x7c1b02a6
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#define KVM_INST_MFSPR_DAR 0x7c1302a6
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#define KVM_INST_MFSPR_DSISR 0x7c1202a6
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#define KVM_INST_MTSPR_SPRG0 0x7c1043a6
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#define KVM_INST_MTSPR_SPRG1 0x7c1143a6
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#define KVM_INST_MTSPR_SPRG2 0x7c1243a6
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#define KVM_INST_MTSPR_SPRG3 0x7c1343a6
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#define KVM_INST_MTSPR_SRR0 0x7c1a03a6
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#define KVM_INST_MTSPR_SRR1 0x7c1b03a6
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#define KVM_INST_MTSPR_DAR 0x7c1303a6
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#define KVM_INST_MTSPR_DSISR 0x7c1203a6
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#define KVM_INST_TLBSYNC 0x7c00046c
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static bool kvm_patching_worked = true;
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static char kvm_tmp[1024 * 1024];
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static int kvm_tmp_index;
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static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
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{
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*inst = new_inst;
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flush_icache_range((ulong)inst, (ulong)inst + 4);
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}
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static void kvm_patch_ins_ld(u32 *inst, long addr, u32 rt)
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{
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#ifdef CONFIG_64BIT
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kvm_patch_ins(inst, KVM_INST_LD | rt | (addr & 0x0000fffc));
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#else
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kvm_patch_ins(inst, KVM_INST_LWZ | rt | ((addr + 4) & 0x0000fffc));
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#endif
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}
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static void kvm_patch_ins_lwz(u32 *inst, long addr, u32 rt)
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{
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kvm_patch_ins(inst, KVM_INST_LWZ | rt | (addr & 0x0000ffff));
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}
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static void kvm_patch_ins_std(u32 *inst, long addr, u32 rt)
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{
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#ifdef CONFIG_64BIT
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kvm_patch_ins(inst, KVM_INST_STD | rt | (addr & 0x0000fffc));
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#else
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kvm_patch_ins(inst, KVM_INST_STW | rt | ((addr + 4) & 0x0000fffc));
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#endif
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}
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static void kvm_patch_ins_stw(u32 *inst, long addr, u32 rt)
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{
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kvm_patch_ins(inst, KVM_INST_STW | rt | (addr & 0x0000fffc));
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}
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static void kvm_patch_ins_nop(u32 *inst)
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{
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kvm_patch_ins(inst, KVM_INST_NOP);
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}
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static u32 *kvm_alloc(int len)
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{
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u32 *p;
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if ((kvm_tmp_index + len) > ARRAY_SIZE(kvm_tmp)) {
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printk(KERN_ERR "KVM: No more space (%d + %d)\n",
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kvm_tmp_index, len);
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kvm_patching_worked = false;
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return NULL;
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}
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p = (void*)&kvm_tmp[kvm_tmp_index];
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kvm_tmp_index += len;
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return p;
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}
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static void kvm_map_magic_page(void *data)
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{
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kvm_hypercall2(KVM_HC_PPC_MAP_MAGIC_PAGE,
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KVM_MAGIC_PAGE, /* Physical Address */
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KVM_MAGIC_PAGE); /* Effective Address */
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}
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static void kvm_check_ins(u32 *inst)
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{
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u32 _inst = *inst;
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u32 inst_no_rt = _inst & ~KVM_MASK_RT;
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u32 inst_rt = _inst & KVM_MASK_RT;
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switch (inst_no_rt) {
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/* Loads */
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case KVM_INST_MFMSR:
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kvm_patch_ins_ld(inst, magic_var(msr), inst_rt);
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break;
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case KVM_INST_MFSPR_SPRG0:
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kvm_patch_ins_ld(inst, magic_var(sprg0), inst_rt);
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break;
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case KVM_INST_MFSPR_SPRG1:
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kvm_patch_ins_ld(inst, magic_var(sprg1), inst_rt);
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break;
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case KVM_INST_MFSPR_SPRG2:
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kvm_patch_ins_ld(inst, magic_var(sprg2), inst_rt);
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break;
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case KVM_INST_MFSPR_SPRG3:
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kvm_patch_ins_ld(inst, magic_var(sprg3), inst_rt);
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break;
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case KVM_INST_MFSPR_SRR0:
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kvm_patch_ins_ld(inst, magic_var(srr0), inst_rt);
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break;
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case KVM_INST_MFSPR_SRR1:
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kvm_patch_ins_ld(inst, magic_var(srr1), inst_rt);
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break;
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case KVM_INST_MFSPR_DAR:
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kvm_patch_ins_ld(inst, magic_var(dar), inst_rt);
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break;
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case KVM_INST_MFSPR_DSISR:
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kvm_patch_ins_lwz(inst, magic_var(dsisr), inst_rt);
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break;
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/* Stores */
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case KVM_INST_MTSPR_SPRG0:
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kvm_patch_ins_std(inst, magic_var(sprg0), inst_rt);
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break;
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case KVM_INST_MTSPR_SPRG1:
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kvm_patch_ins_std(inst, magic_var(sprg1), inst_rt);
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break;
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case KVM_INST_MTSPR_SPRG2:
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kvm_patch_ins_std(inst, magic_var(sprg2), inst_rt);
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break;
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case KVM_INST_MTSPR_SPRG3:
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kvm_patch_ins_std(inst, magic_var(sprg3), inst_rt);
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break;
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case KVM_INST_MTSPR_SRR0:
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kvm_patch_ins_std(inst, magic_var(srr0), inst_rt);
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break;
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case KVM_INST_MTSPR_SRR1:
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kvm_patch_ins_std(inst, magic_var(srr1), inst_rt);
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break;
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case KVM_INST_MTSPR_DAR:
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kvm_patch_ins_std(inst, magic_var(dar), inst_rt);
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break;
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case KVM_INST_MTSPR_DSISR:
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kvm_patch_ins_stw(inst, magic_var(dsisr), inst_rt);
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break;
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/* Nops */
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case KVM_INST_TLBSYNC:
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kvm_patch_ins_nop(inst);
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break;
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}
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switch (_inst) {
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}
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}
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static void kvm_use_magic_page(void)
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{
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u32 *p;
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u32 *start, *end;
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u32 tmp;
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/* Tell the host to map the magic page to -4096 on all CPUs */
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on_each_cpu(kvm_map_magic_page, NULL, 1);
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/* Quick self-test to see if the mapping works */
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if (__get_user(tmp, (u32*)KVM_MAGIC_PAGE)) {
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kvm_patching_worked = false;
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return;
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}
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/* Now loop through all code and find instructions */
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start = (void*)_stext;
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end = (void*)_etext;
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for (p = start; p < end; p++)
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kvm_check_ins(p);
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printk(KERN_INFO "KVM: Live patching for a fast VM %s\n",
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kvm_patching_worked ? "worked" : "failed");
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}
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unsigned long kvm_hypercall(unsigned long *in,
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unsigned long *out,
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unsigned long nr)
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{
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unsigned long register r0 asm("r0");
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unsigned long register r3 asm("r3") = in[0];
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unsigned long register r4 asm("r4") = in[1];
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unsigned long register r5 asm("r5") = in[2];
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unsigned long register r6 asm("r6") = in[3];
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unsigned long register r7 asm("r7") = in[4];
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unsigned long register r8 asm("r8") = in[5];
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unsigned long register r9 asm("r9") = in[6];
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unsigned long register r10 asm("r10") = in[7];
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unsigned long register r11 asm("r11") = nr;
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unsigned long register r12 asm("r12");
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asm volatile("bl kvm_hypercall_start"
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: "=r"(r0), "=r"(r3), "=r"(r4), "=r"(r5), "=r"(r6),
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"=r"(r7), "=r"(r8), "=r"(r9), "=r"(r10), "=r"(r11),
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"=r"(r12)
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: "r"(r3), "r"(r4), "r"(r5), "r"(r6), "r"(r7), "r"(r8),
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"r"(r9), "r"(r10), "r"(r11)
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: "memory", "cc", "xer", "ctr", "lr");
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out[0] = r4;
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out[1] = r5;
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out[2] = r6;
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out[3] = r7;
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out[4] = r8;
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out[5] = r9;
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out[6] = r10;
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out[7] = r11;
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return r3;
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}
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EXPORT_SYMBOL_GPL(kvm_hypercall);
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static int kvm_para_setup(void)
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{
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extern u32 kvm_hypercall_start;
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struct device_node *hyper_node;
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u32 *insts;
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int len, i;
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hyper_node = of_find_node_by_path("/hypervisor");
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if (!hyper_node)
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return -1;
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insts = (u32*)of_get_property(hyper_node, "hcall-instructions", &len);
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if (len % 4)
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return -1;
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if (len > (4 * 4))
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return -1;
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for (i = 0; i < (len / 4); i++)
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kvm_patch_ins(&(&kvm_hypercall_start)[i], insts[i]);
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return 0;
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}
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static __init void kvm_free_tmp(void)
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{
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unsigned long start, end;
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start = (ulong)&kvm_tmp[kvm_tmp_index + (PAGE_SIZE - 1)] & PAGE_MASK;
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end = (ulong)&kvm_tmp[ARRAY_SIZE(kvm_tmp)] & PAGE_MASK;
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/* Free the tmp space we don't need */
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for (; start < end; start += PAGE_SIZE) {
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ClearPageReserved(virt_to_page(start));
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init_page_count(virt_to_page(start));
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free_page(start);
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totalram_pages++;
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}
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}
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static int __init kvm_guest_init(void)
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{
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if (!kvm_para_available())
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goto free_tmp;
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if (kvm_para_setup())
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goto free_tmp;
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if (kvm_para_has_feature(KVM_FEATURE_MAGIC_PAGE))
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kvm_use_magic_page();
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free_tmp:
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kvm_free_tmp();
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return 0;
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}
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postcore_initcall(kvm_guest_init);
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