![Alexander Graf](/assets/img/avatar_default.png)
We will need to patch several instruction streams over to a different code path, so we need a way to patch a single instruction with a branch somewhere else. This patch adds a helper to facilitate this patching. Signed-off-by: Alexander Graf <agraf@suse.de> Signed-off-by: Avi Kivity <avi@redhat.com>
340 lines
8.4 KiB
C
340 lines
8.4 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 void kvm_patch_ins_b(u32 *inst, int addr)
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{
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#ifdef CONFIG_RELOCATABLE
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/* On relocatable kernels interrupts handlers and our code
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can be in different regions, so we don't patch them */
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extern u32 __end_interrupts;
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if ((ulong)inst < (ulong)&__end_interrupts)
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return;
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#endif
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kvm_patch_ins(inst, KVM_INST_B | (addr & KVM_INST_B_MASK));
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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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