arch/powerpc/kernel/kvm_emul.S

/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * Copyright SUSE Linux Products GmbH 2010
 *
 * Authors: Alexander Graf <agraf@suse.de>
 */

#include <asm/ppc_asm.h>
#include <asm/kvm_asm.h>
#include <asm/reg.h>
#include <asm/page.h>
#include <asm/asm-offsets.h>

/* Hypercall entry point. Will be patched with device tree instructions. */

.global kvm_hypercall_start
kvm_hypercall_start:
	li	r3, -1
	nop
	nop
	nop
	blr

#define KVM_MAGIC_PAGE		(-4096)

#ifdef CONFIG_64BIT
#define LL64(reg, offs, reg2)	ld	reg, (offs)(reg2)
#define STL64(reg, offs, reg2)	std	reg, (offs)(reg2)
#else
#define LL64(reg, offs, reg2)	lwz	reg, (offs + 4)(reg2)
#define STL64(reg, offs, reg2)	stw	reg, (offs + 4)(reg2)
#endif

#define SCRATCH_SAVE							\
	/* Enable critical section. We are critical if			\
	   shared->critical == r1 */					\
	STL64(r1, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0);		\
									\
	/* Save state */						\
	PPC_STL	r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH1)(0);		\
	PPC_STL	r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH2)(0);		\
	mfcr	r31;							\
	stw	r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH3)(0);

#define SCRATCH_RESTORE							\
	/* Restore state */						\
	PPC_LL	r31, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH1)(0);		\
	lwz	r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH3)(0);		\
	mtcr	r30;							\
	PPC_LL	r30, (KVM_MAGIC_PAGE + KVM_MAGIC_SCRATCH2)(0);		\
									\
	/* Disable critical section. We are critical if			\
	   shared->critical == r1 and r2 is always != r1 */		\
	STL64(r2, KVM_MAGIC_PAGE + KVM_MAGIC_CRITICAL, 0);

.global kvm_emulate_mtmsrd
kvm_emulate_mtmsrd:

	SCRATCH_SAVE

	/* Put MSR & ~(MSR_EE|MSR_RI) in r31 */
	LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)
	lis	r30, (~(MSR_EE | MSR_RI))@h
	ori	r30, r30, (~(MSR_EE | MSR_RI))@l
	and	r31, r31, r30

	/* OR the register's (MSR_EE|MSR_RI) on MSR */
kvm_emulate_mtmsrd_reg:
	andi.	r30, r0, (MSR_EE|MSR_RI)
	or	r31, r31, r30

	/* Put MSR back into magic page */
	STL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)

	/* Check if we have to fetch an interrupt */
	lwz	r31, (KVM_MAGIC_PAGE + KVM_MAGIC_INT)(0)
	cmpwi	r31, 0
	beq+	no_check

	/* Check if we may trigger an interrupt */
	andi.	r30, r30, MSR_EE
	beq	no_check

	SCRATCH_RESTORE

	/* Nag hypervisor */
	tlbsync

	b	kvm_emulate_mtmsrd_branch

no_check:

	SCRATCH_RESTORE

	/* Go back to caller */
kvm_emulate_mtmsrd_branch:
	b	.
kvm_emulate_mtmsrd_end:

.global kvm_emulate_mtmsrd_branch_offs
kvm_emulate_mtmsrd_branch_offs:
	.long (kvm_emulate_mtmsrd_branch - kvm_emulate_mtmsrd) / 4

.global kvm_emulate_mtmsrd_reg_offs
kvm_emulate_mtmsrd_reg_offs:
	.long (kvm_emulate_mtmsrd_reg - kvm_emulate_mtmsrd) / 4

.global kvm_emulate_mtmsrd_len
kvm_emulate_mtmsrd_len:
	.long (kvm_emulate_mtmsrd_end - kvm_emulate_mtmsrd) / 4


#define MSR_SAFE_BITS (MSR_EE | MSR_CE | MSR_ME | MSR_RI)
#define MSR_CRITICAL_BITS ~MSR_SAFE_BITS

.global kvm_emulate_mtmsr
kvm_emulate_mtmsr:

	SCRATCH_SAVE

	/* Fetch old MSR in r31 */
	LL64(r31, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)

	/* Find the changed bits between old and new MSR */
kvm_emulate_mtmsr_reg1:
	xor	r31, r0, r31

	/* Check if we need to really do mtmsr */
	LOAD_REG_IMMEDIATE(r30, MSR_CRITICAL_BITS)
	and.	r31, r31, r30

	/* No critical bits changed? Maybe we can stay in the guest. */
	beq	maybe_stay_in_guest

do_mtmsr:

	SCRATCH_RESTORE

	/* Just fire off the mtmsr if it's critical */
kvm_emulate_mtmsr_orig_ins:
	mtmsr	r0

	b	kvm_emulate_mtmsr_branch

maybe_stay_in_guest:

	/* Check if we have to fetch an interrupt */
	lwz	r31, (KVM_MAGIC_PAGE + KVM_MAGIC_INT)(0)
	cmpwi	r31, 0
	beq+	no_mtmsr

	/* Check if we may trigger an interrupt */
kvm_emulate_mtmsr_reg2:
	andi.	r31, r0, MSR_EE
	beq	no_mtmsr

	b	do_mtmsr

no_mtmsr:

	/* Put MSR into magic page because we don't call mtmsr */
kvm_emulate_mtmsr_reg3:
	STL64(r0, KVM_MAGIC_PAGE + KVM_MAGIC_MSR, 0)

	SCRATCH_RESTORE

	/* Go back to caller */
kvm_emulate_mtmsr_branch:
	b	.
kvm_emulate_mtmsr_end:

.global kvm_emulate_mtmsr_branch_offs
kvm_emulate_mtmsr_branch_offs:
	.long (kvm_emulate_mtmsr_branch - kvm_emulate_mtmsr) / 4

.global kvm_emulate_mtmsr_reg1_offs
kvm_emulate_mtmsr_reg1_offs:
	.long (kvm_emulate_mtmsr_reg1 - kvm_emulate_mtmsr) / 4

.global kvm_emulate_mtmsr_reg2_offs
kvm_emulate_mtmsr_reg2_offs:
	.long (kvm_emulate_mtmsr_reg2 - kvm_emulate_mtmsr) / 4

.global kvm_emulate_mtmsr_reg3_offs
kvm_emulate_mtmsr_reg3_offs:
	.long (kvm_emulate_mtmsr_reg3 - kvm_emulate_mtmsr) / 4

.global kvm_emulate_mtmsr_orig_ins_offs
kvm_emulate_mtmsr_orig_ins_offs:
	.long (kvm_emulate_mtmsr_orig_ins - kvm_emulate_mtmsr) / 4

.global kvm_emulate_mtmsr_len
kvm_emulate_mtmsr_len:
	.long (kvm_emulate_mtmsr_end - kvm_emulate_mtmsr) / 4