/*
 * 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 2009
 *
 * 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>
#include <asm/exception-64s.h>
#include <asm/asm-compat.h>

#if defined(CONFIG_PPC_BOOK3S_64)
#ifdef PPC64_ELF_ABI_v2
#define FUNC(name)              name
#else
#define FUNC(name)              GLUE(.,name)
#endif
#define GET_SHADOW_VCPU(reg)    addi    reg, r13, PACA_SVCPU

#elif defined(CONFIG_PPC_BOOK3S_32)
#define FUNC(name)              name
#define GET_SHADOW_VCPU(reg)    lwz     reg, (THREAD + THREAD_KVM_SVCPU)(r2)

#endif /* CONFIG_PPC_BOOK3S_XX */

#define VCPU_LOAD_NVGPRS(vcpu) \
        PPC_LL  r14, VCPU_GPR(R14)(vcpu); \
        PPC_LL  r15, VCPU_GPR(R15)(vcpu); \
        PPC_LL  r16, VCPU_GPR(R16)(vcpu); \
        PPC_LL  r17, VCPU_GPR(R17)(vcpu); \
        PPC_LL  r18, VCPU_GPR(R18)(vcpu); \
        PPC_LL  r19, VCPU_GPR(R19)(vcpu); \
        PPC_LL  r20, VCPU_GPR(R20)(vcpu); \
        PPC_LL  r21, VCPU_GPR(R21)(vcpu); \
        PPC_LL  r22, VCPU_GPR(R22)(vcpu); \
        PPC_LL  r23, VCPU_GPR(R23)(vcpu); \
        PPC_LL  r24, VCPU_GPR(R24)(vcpu); \
        PPC_LL  r25, VCPU_GPR(R25)(vcpu); \
        PPC_LL  r26, VCPU_GPR(R26)(vcpu); \
        PPC_LL  r27, VCPU_GPR(R27)(vcpu); \
        PPC_LL  r28, VCPU_GPR(R28)(vcpu); \
        PPC_LL  r29, VCPU_GPR(R29)(vcpu); \
        PPC_LL  r30, VCPU_GPR(R30)(vcpu); \
        PPC_LL  r31, VCPU_GPR(R31)(vcpu); \

/*****************************************************************************
 *                                                                           *
 *     Guest entry / exit code that is in kernel module memory (highmem)     *
 *                                                                           *
 ****************************************************************************/

/* Registers:
 *  r3: kvm_run pointer
 *  r4: vcpu pointer
 */
_GLOBAL(__kvmppc_vcpu_run)

kvm_start_entry:
        /* Write correct stack frame */
        mflr    r0
        PPC_STL r0,PPC_LR_STKOFF(r1)

        /* Save host state to the stack */
        PPC_STLU r1, -SWITCH_FRAME_SIZE(r1)

        /* Save r3 (kvm_run) and r4 (vcpu) */
        SAVE_2GPRS(3, r1)

        /* Save non-volatile registers (r14 - r31) */
        SAVE_NVGPRS(r1)

        /* Save CR */
        mfcr    r14
        stw     r14, _CCR(r1)

        /* Save LR */
        PPC_STL r0, _LINK(r1)

        /* Load non-volatile guest state from the vcpu */
        VCPU_LOAD_NVGPRS(r4)

kvm_start_lightweight:
        /* Copy registers into shadow vcpu so we can access them in real mode */
        mr      r3, r4
        bl      FUNC(kvmppc_copy_to_svcpu)
        nop
        REST_GPR(4, r1)

#ifdef CONFIG_PPC_BOOK3S_64
        /* Get the dcbz32 flag */
        PPC_LL  r3, VCPU_HFLAGS(r4)
        rldicl  r3, r3, 0, 63           /* r3 &= 1 */
        stb     r3, HSTATE_RESTORE_HID5(r13)

        /* Load up guest SPRG3 value, since it's user readable */
        lwz     r3, VCPU_SHAREDBE(r4)
        cmpwi   r3, 0
        ld      r5, VCPU_SHARED(r4)
        beq     sprg3_little_endian
sprg3_big_endian:
#ifdef __BIG_ENDIAN__
        ld      r3, VCPU_SHARED_SPRG3(r5)
#else
        addi    r5, r5, VCPU_SHARED_SPRG3
        ldbrx   r3, 0, r5
#endif
        b       after_sprg3_load
sprg3_little_endian:
#ifdef __LITTLE_ENDIAN__
        ld      r3, VCPU_SHARED_SPRG3(r5)
#else
        addi    r5, r5, VCPU_SHARED_SPRG3
        ldbrx   r3, 0, r5
#endif

after_sprg3_load:
        mtspr   SPRN_SPRG3, r3
#endif /* CONFIG_PPC_BOOK3S_64 */

        PPC_LL  r4, VCPU_SHADOW_MSR(r4) /* get shadow_msr */

        /* Jump to segment patching handler and into our guest */
        bl      FUNC(kvmppc_entry_trampoline)
        nop

/*
 * This is the handler in module memory. It gets jumped at from the
 * lowmem trampoline code, so it's basically the guest exit code.
 *
 */

        /*
         * Register usage at this point:
         *
         * R1       = host R1
         * R2       = host R2
         * R12      = exit handler id
         * R13      = PACA
         * SVCPU.*  = guest *
         * MSR.EE   = 1
         *
         */

        PPC_LL  r3, GPR4(r1)            /* vcpu pointer */

        /*
         * kvmppc_copy_from_svcpu can clobber volatile registers, save
         * the exit handler id to the vcpu and restore it from there later.
         */
        stw     r12, VCPU_TRAP(r3)

        /* Transfer reg values from shadow vcpu back to vcpu struct */

        bl      FUNC(kvmppc_copy_from_svcpu)
        nop

#ifdef CONFIG_PPC_BOOK3S_64
        /*
         * Reload kernel SPRG3 value.
         * No need to save guest value as usermode can't modify SPRG3.
         */
        ld      r3, PACA_SPRG_VDSO(r13)
        mtspr   SPRN_SPRG_VDSO_WRITE, r3
#endif /* CONFIG_PPC_BOOK3S_64 */

        /* R7 = vcpu */
        PPC_LL  r7, GPR4(r1)

        PPC_STL r14, VCPU_GPR(R14)(r7)
        PPC_STL r15, VCPU_GPR(R15)(r7)
        PPC_STL r16, VCPU_GPR(R16)(r7)
        PPC_STL r17, VCPU_GPR(R17)(r7)
        PPC_STL r18, VCPU_GPR(R18)(r7)
        PPC_STL r19, VCPU_GPR(R19)(r7)
        PPC_STL r20, VCPU_GPR(R20)(r7)
        PPC_STL r21, VCPU_GPR(R21)(r7)
        PPC_STL r22, VCPU_GPR(R22)(r7)
        PPC_STL r23, VCPU_GPR(R23)(r7)
        PPC_STL r24, VCPU_GPR(R24)(r7)
        PPC_STL r25, VCPU_GPR(R25)(r7)
        PPC_STL r26, VCPU_GPR(R26)(r7)
        PPC_STL r27, VCPU_GPR(R27)(r7)
        PPC_STL r28, VCPU_GPR(R28)(r7)
        PPC_STL r29, VCPU_GPR(R29)(r7)
        PPC_STL r30, VCPU_GPR(R30)(r7)
        PPC_STL r31, VCPU_GPR(R31)(r7)

        /* Pass the exit number as 3rd argument to kvmppc_handle_exit */
        lwz     r5, VCPU_TRAP(r7)

        /* Restore r3 (kvm_run) and r4 (vcpu) */
        REST_2GPRS(3, r1)
        bl      FUNC(kvmppc_handle_exit_pr)

        /* If RESUME_GUEST, get back in the loop */
        cmpwi   r3, RESUME_GUEST
        beq     kvm_loop_lightweight

        cmpwi   r3, RESUME_GUEST_NV
        beq     kvm_loop_heavyweight

kvm_exit_loop:

        PPC_LL  r4, _LINK(r1)
        mtlr    r4

        lwz     r14, _CCR(r1)
        mtcr    r14

        /* Restore non-volatile host registers (r14 - r31) */
        REST_NVGPRS(r1)

        addi    r1, r1, SWITCH_FRAME_SIZE
        blr

kvm_loop_heavyweight:

        PPC_LL  r4, _LINK(r1)
        PPC_STL r4, (PPC_LR_STKOFF + SWITCH_FRAME_SIZE)(r1)

        /* Load vcpu and cpu_run */
        REST_2GPRS(3, r1)

        /* Load non-volatile guest state from the vcpu */
        VCPU_LOAD_NVGPRS(r4)

        /* Jump back into the beginning of this function */
        b       kvm_start_lightweight

kvm_loop_lightweight:

        /* We'll need the vcpu pointer */
        REST_GPR(4, r1)

        /* Jump back into the beginning of this function */
        b       kvm_start_lightweight