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KVM/MIPS32: Binary patching of select privileged instructions. 

Currently, the following instructions are translated:
- CACHE (indexed)
- CACHE (va based): translated to a SYNCI, overkill on D-CACHE operations,
  but still much faster than a trap.
- mfc0/mtc0: the virtual COP0 registers for the guest are implemented as
  2-D array.
  [COP#][SEL] and this is mapped into the guest kernel address space @ VA 0x0.
  mfc0/mtc0 operations are transformed to load/stores.

Signed-off-by: Sanjay Lal <sanjayl@kymasys.com>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Sanjay Lal 2012-11-21 18:34:16 -08:00 committed by Ralf Baechle
parent 2f4d9b5442
commit 50c8308538
3 changed files with 209 additions and 0 deletions
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23
arch/mips/kvm/kvm_mips_comm.h Normal file
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* KVM/MIPS: commpage: mapped into get kernel space
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
#ifndef __KVM_MIPS_COMMPAGE_H__
#define __KVM_MIPS_COMMPAGE_H__
struct kvm_mips_commpage {
struct mips_coproc cop0; /* COP0 state is mapped into Guest kernel via commpage */
};
#define KVM_MIPS_COMM_EIDI_OFFSET 0x0
extern void kvm_mips_commpage_init(struct kvm_vcpu *vcpu);
#endif /* __KVM_MIPS_COMMPAGE_H__ */

37
arch/mips/kvm/kvm_mips_commpage.c Normal file
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* commpage, currently used for Virtual COP0 registers.
* Mapped into the guest kernel @ 0x0.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/bootmem.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <linux/kvm_host.h>
#include "kvm_mips_comm.h"
void kvm_mips_commpage_init(struct kvm_vcpu *vcpu)
{
struct kvm_mips_commpage *page = vcpu->arch.kseg0_commpage;
memset(page, 0, sizeof(struct kvm_mips_commpage));
/* Specific init values for fields */
vcpu->arch.cop0 = &page->cop0;
memset(vcpu->arch.cop0, 0, sizeof(struct mips_coproc));
return;
}

149
arch/mips/kvm/kvm_mips_dyntrans.c Normal file
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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/bootmem.h>
#include "kvm_mips_comm.h"
#define SYNCI_TEMPLATE 0x041f0000
#define SYNCI_BASE(x) (((x) >> 21) & 0x1f)
#define SYNCI_OFFSET ((x) & 0xffff)
#define LW_TEMPLATE 0x8c000000
#define CLEAR_TEMPLATE 0x00000020
#define SW_TEMPLATE 0xac000000
int
kvm_mips_trans_cache_index(uint32_t inst, uint32_t *opc,
struct kvm_vcpu *vcpu)
{
int result = 0;
unsigned long kseg0_opc;
uint32_t synci_inst = 0x0;
/* Replace the CACHE instruction, with a NOP */
kseg0_opc =
CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
(vcpu, (unsigned long) opc));
memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
mips32_SyncICache(kseg0_opc, 32);
return result;
}
/*
* Address based CACHE instructions are transformed into synci(s). A little heavy
* for just D-cache invalidates, but avoids an expensive trap
*/
int
kvm_mips_trans_cache_va(uint32_t inst, uint32_t *opc,
struct kvm_vcpu *vcpu)
{
int result = 0;
unsigned long kseg0_opc;
uint32_t synci_inst = SYNCI_TEMPLATE, base, offset;
base = (inst >> 21) & 0x1f;
offset = inst & 0xffff;
synci_inst |= (base << 21);
synci_inst |= offset;
kseg0_opc =
CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
(vcpu, (unsigned long) opc));
memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
mips32_SyncICache(kseg0_opc, 32);
return result;
}
int
kvm_mips_trans_mfc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
{
int32_t rt, rd, sel;
uint32_t mfc0_inst;
unsigned long kseg0_opc, flags;
rt = (inst >> 16) & 0x1f;
rd = (inst >> 11) & 0x1f;
sel = inst & 0x7;
if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) {
mfc0_inst = CLEAR_TEMPLATE;
mfc0_inst |= ((rt & 0x1f) << 16);
} else {
mfc0_inst = LW_TEMPLATE;
mfc0_inst |= ((rt & 0x1f) << 16);
mfc0_inst |=
offsetof(struct mips_coproc,
reg[rd][sel]) + offsetof(struct kvm_mips_commpage,
cop0);
}
if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
kseg0_opc =
CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
(vcpu, (unsigned long) opc));
memcpy((void *)kseg0_opc, (void *)&mfc0_inst, sizeof(uint32_t));
mips32_SyncICache(kseg0_opc, 32);
} else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
local_irq_save(flags);
memcpy((void *)opc, (void *)&mfc0_inst, sizeof(uint32_t));
mips32_SyncICache((unsigned long) opc, 32);
local_irq_restore(flags);
} else {
kvm_err("%s: Invalid address: %p\n", __func__, opc);
return -EFAULT;
}
return 0;
}
int
kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
{
int32_t rt, rd, sel;
uint32_t mtc0_inst = SW_TEMPLATE;
unsigned long kseg0_opc, flags;
rt = (inst >> 16) & 0x1f;
rd = (inst >> 11) & 0x1f;
sel = inst & 0x7;
mtc0_inst |= ((rt & 0x1f) << 16);
mtc0_inst |=
offsetof(struct mips_coproc,
reg[rd][sel]) + offsetof(struct kvm_mips_commpage, cop0);
if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
kseg0_opc =
CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
(vcpu, (unsigned long) opc));
memcpy((void *)kseg0_opc, (void *)&mtc0_inst, sizeof(uint32_t));
mips32_SyncICache(kseg0_opc, 32);
} else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
local_irq_save(flags);
memcpy((void *)opc, (void *)&mtc0_inst, sizeof(uint32_t));
mips32_SyncICache((unsigned long) opc, 32);
local_irq_restore(flags);
} else {
kvm_err("%s: Invalid address: %p\n", __func__, opc);
return -EFAULT;
}
return 0;
}