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KVM/MIPS32: Entry point for trampolining to the guest and trap handlers.

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- __kvm_mips_vcpu_run: main entry point to enter guest, we save kernel context, load
  up guest context from and ERET to guest context.
- mips32_exception: L1 exception handler(s), save k0/k1 and jump to main handlers.
- mips32_GuestException: Generic exception handlers for exceptions/interrupts while in
  guest context.  Save guest context, restore some kernel context and jump to
  main 'C' handler: kvm_mips_handle_exit()

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 18:34:01 -08:00 committed by Ralf Baechle
parent 740765ce45
commit b680f70fc1
1 changed files with 650 additions and 0 deletions
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650
arch/mips/kvm/kvm_locore.S 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.
*
* Main entry point for the guest, exception handling.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
* Authors: Sanjay Lal <sanjayl@kymasys.com>
*/
#include <asm/asm.h>
#include <asm/asmmacro.h>
#include <asm/regdef.h>
#include <asm/mipsregs.h>
#include <asm/stackframe.h>
#include <asm/asm-offsets.h>
#define _C_LABEL(x) x
#define MIPSX(name) mips32_ ## name
#define CALLFRAME_SIZ 32
/*
* VECTOR
* exception vector entrypoint
*/
#define VECTOR(x, regmask) \
.ent _C_LABEL(x),0; \
EXPORT(x);
#define VECTOR_END(x) \
EXPORT(x);
/* Overload, Danger Will Robinson!! */
#define PT_HOST_ASID PT_BVADDR
#define PT_HOST_USERLOCAL PT_EPC
#define CP0_DDATA_LO $28,3
#define CP0_EBASE $15,1
#define CP0_INTCTL $12,1
#define CP0_SRSCTL $12,2
#define CP0_SRSMAP $12,3
#define CP0_HWRENA $7,0
/* Resume Flags */
#define RESUME_FLAG_HOST (1<<1) /* Resume host? */
#define RESUME_GUEST 0
#define RESUME_HOST RESUME_FLAG_HOST
/*
* __kvm_mips_vcpu_run: entry point to the guest
* a0: run
* a1: vcpu
*/
FEXPORT(__kvm_mips_vcpu_run)
.set push
.set noreorder
.set noat
/* k0/k1 not being used in host kernel context */
addiu k1,sp, -PT_SIZE
LONG_S $0, PT_R0(k1)
LONG_S $1, PT_R1(k1)
LONG_S $2, PT_R2(k1)
LONG_S $3, PT_R3(k1)
LONG_S $4, PT_R4(k1)
LONG_S $5, PT_R5(k1)
LONG_S $6, PT_R6(k1)
LONG_S $7, PT_R7(k1)
LONG_S $8, PT_R8(k1)
LONG_S $9, PT_R9(k1)
LONG_S $10, PT_R10(k1)
LONG_S $11, PT_R11(k1)
LONG_S $12, PT_R12(k1)
LONG_S $13, PT_R13(k1)
LONG_S $14, PT_R14(k1)
LONG_S $15, PT_R15(k1)
LONG_S $16, PT_R16(k1)
LONG_S $17, PT_R17(k1)
LONG_S $18, PT_R18(k1)
LONG_S $19, PT_R19(k1)
LONG_S $20, PT_R20(k1)
LONG_S $21, PT_R21(k1)
LONG_S $22, PT_R22(k1)
LONG_S $23, PT_R23(k1)
LONG_S $24, PT_R24(k1)
LONG_S $25, PT_R25(k1)
/* XXXKYMA k0/k1 not saved, not being used if we got here through an ioctl() */
LONG_S $28, PT_R28(k1)
LONG_S $29, PT_R29(k1)
LONG_S $30, PT_R30(k1)
LONG_S $31, PT_R31(k1)
/* Save hi/lo */
mflo v0
LONG_S v0, PT_LO(k1)
mfhi v1
LONG_S v1, PT_HI(k1)
/* Save host status */
mfc0 v0, CP0_STATUS
LONG_S v0, PT_STATUS(k1)
/* Save host ASID, shove it into the BVADDR location */
mfc0 v1,CP0_ENTRYHI
andi v1, 0xff
LONG_S v1, PT_HOST_ASID(k1)
/* Save DDATA_LO, will be used to store pointer to vcpu */
mfc0 v1, CP0_DDATA_LO
LONG_S v1, PT_HOST_USERLOCAL(k1)
/* DDATA_LO has pointer to vcpu */
mtc0 a1,CP0_DDATA_LO
/* Offset into vcpu->arch */
addiu k1, a1, VCPU_HOST_ARCH
/* Save the host stack to VCPU, used for exception processing when we exit from the Guest */
LONG_S sp, VCPU_HOST_STACK(k1)
/* Save the kernel gp as well */
LONG_S gp, VCPU_HOST_GP(k1)
/* Setup status register for running the guest in UM, interrupts are disabled */
li k0,(ST0_EXL | KSU_USER| ST0_BEV)
mtc0 k0,CP0_STATUS
ehb
/* load up the new EBASE */
LONG_L k0, VCPU_GUEST_EBASE(k1)
mtc0 k0,CP0_EBASE
/* Now that the new EBASE has been loaded, unset BEV, set interrupt mask as it was
* but make sure that timer interrupts are enabled
*/
li k0,(ST0_EXL | KSU_USER | ST0_IE)
andi v0, v0, ST0_IM
or k0, k0, v0
mtc0 k0,CP0_STATUS
ehb
/* Set Guest EPC */
LONG_L t0, VCPU_PC(k1)
mtc0 t0, CP0_EPC
FEXPORT(__kvm_mips_load_asid)
/* Set the ASID for the Guest Kernel */
sll t0, t0, 1 /* with kseg0 @ 0x40000000, kernel */
/* addresses shift to 0x80000000 */
bltz t0, 1f /* If kernel */
addiu t1, k1, VCPU_GUEST_KERNEL_ASID /* (BD) */
addiu t1, k1, VCPU_GUEST_USER_ASID /* else user */
1:
/* t1: contains the base of the ASID array, need to get the cpu id */
LONG_L t2, TI_CPU($28) /* smp_processor_id */
sll t2, t2, 2 /* x4 */
addu t3, t1, t2
LONG_L k0, (t3)
andi k0, k0, 0xff
mtc0 k0,CP0_ENTRYHI
ehb
/* Disable RDHWR access */
mtc0 zero, CP0_HWRENA
/* Now load up the Guest Context from VCPU */
LONG_L $1, VCPU_R1(k1)
LONG_L $2, VCPU_R2(k1)
LONG_L $3, VCPU_R3(k1)
LONG_L $4, VCPU_R4(k1)
LONG_L $5, VCPU_R5(k1)
LONG_L $6, VCPU_R6(k1)
LONG_L $7, VCPU_R7(k1)
LONG_L $8, VCPU_R8(k1)
LONG_L $9, VCPU_R9(k1)
LONG_L $10, VCPU_R10(k1)
LONG_L $11, VCPU_R11(k1)
LONG_L $12, VCPU_R12(k1)
LONG_L $13, VCPU_R13(k1)
LONG_L $14, VCPU_R14(k1)
LONG_L $15, VCPU_R15(k1)
LONG_L $16, VCPU_R16(k1)
LONG_L $17, VCPU_R17(k1)
LONG_L $18, VCPU_R18(k1)
LONG_L $19, VCPU_R19(k1)
LONG_L $20, VCPU_R20(k1)
LONG_L $21, VCPU_R21(k1)
LONG_L $22, VCPU_R22(k1)
LONG_L $23, VCPU_R23(k1)
LONG_L $24, VCPU_R24(k1)
LONG_L $25, VCPU_R25(k1)
/* k0/k1 loaded up later */
LONG_L $28, VCPU_R28(k1)
LONG_L $29, VCPU_R29(k1)
LONG_L $30, VCPU_R30(k1)
LONG_L $31, VCPU_R31(k1)
/* Restore hi/lo */
LONG_L k0, VCPU_LO(k1)
mtlo k0
LONG_L k0, VCPU_HI(k1)
mthi k0
FEXPORT(__kvm_mips_load_k0k1)
/* Restore the guest's k0/k1 registers */
LONG_L k0, VCPU_R26(k1)
LONG_L k1, VCPU_R27(k1)
/* Jump to guest */
eret
.set pop
VECTOR(MIPSX(exception), unknown)
/*
* Find out what mode we came from and jump to the proper handler.
*/
.set push
.set noat
.set noreorder
mtc0 k0, CP0_ERROREPC #01: Save guest k0
ehb #02:
mfc0 k0, CP0_EBASE #02: Get EBASE
srl k0, k0, 10 #03: Get rid of CPUNum
sll k0, k0, 10 #04
LONG_S k1, 0x3000(k0) #05: Save k1 @ offset 0x3000
addiu k0, k0, 0x2000 #06: Exception handler is installed @ offset 0x2000
j k0 #07: jump to the function
nop #08: branch delay slot
.set push
VECTOR_END(MIPSX(exceptionEnd))
.end MIPSX(exception)
/*
* Generic Guest exception handler. We end up here when the guest
* does something that causes a trap to kernel mode.
*
*/
NESTED (MIPSX(GuestException), CALLFRAME_SIZ, ra)
.set push
.set noat
.set noreorder
/* Get the VCPU pointer from DDTATA_LO */
mfc0 k1, CP0_DDATA_LO
addiu k1, k1, VCPU_HOST_ARCH
/* Start saving Guest context to VCPU */
LONG_S $0, VCPU_R0(k1)
LONG_S $1, VCPU_R1(k1)
LONG_S $2, VCPU_R2(k1)
LONG_S $3, VCPU_R3(k1)
LONG_S $4, VCPU_R4(k1)
LONG_S $5, VCPU_R5(k1)
LONG_S $6, VCPU_R6(k1)
LONG_S $7, VCPU_R7(k1)
LONG_S $8, VCPU_R8(k1)
LONG_S $9, VCPU_R9(k1)
LONG_S $10, VCPU_R10(k1)
LONG_S $11, VCPU_R11(k1)
LONG_S $12, VCPU_R12(k1)
LONG_S $13, VCPU_R13(k1)
LONG_S $14, VCPU_R14(k1)
LONG_S $15, VCPU_R15(k1)
LONG_S $16, VCPU_R16(k1)
LONG_S $17,VCPU_R17(k1)
LONG_S $18, VCPU_R18(k1)
LONG_S $19, VCPU_R19(k1)
LONG_S $20, VCPU_R20(k1)
LONG_S $21, VCPU_R21(k1)
LONG_S $22, VCPU_R22(k1)
LONG_S $23, VCPU_R23(k1)
LONG_S $24, VCPU_R24(k1)
LONG_S $25, VCPU_R25(k1)
/* Guest k0/k1 saved later */
LONG_S $28, VCPU_R28(k1)
LONG_S $29, VCPU_R29(k1)
LONG_S $30, VCPU_R30(k1)
LONG_S $31, VCPU_R31(k1)
/* We need to save hi/lo and restore them on
* the way out
*/
mfhi t0
LONG_S t0, VCPU_HI(k1)
mflo t0
LONG_S t0, VCPU_LO(k1)
/* Finally save guest k0/k1 to VCPU */
mfc0 t0, CP0_ERROREPC
LONG_S t0, VCPU_R26(k1)
/* Get GUEST k1 and save it in VCPU */
la t1, ~0x2ff
mfc0 t0, CP0_EBASE
and t0, t0, t1
LONG_L t0, 0x3000(t0)
LONG_S t0, VCPU_R27(k1)
/* Now that context has been saved, we can use other registers */
/* Restore vcpu */
mfc0 a1, CP0_DDATA_LO
move s1, a1
/* Restore run (vcpu->run) */
LONG_L a0, VCPU_RUN(a1)
/* Save pointer to run in s0, will be saved by the compiler */
move s0, a0
/* Save Host level EPC, BadVaddr and Cause to VCPU, useful to process the exception */
mfc0 k0,CP0_EPC
LONG_S k0, VCPU_PC(k1)
mfc0 k0, CP0_BADVADDR
LONG_S k0, VCPU_HOST_CP0_BADVADDR(k1)
mfc0 k0, CP0_CAUSE
LONG_S k0, VCPU_HOST_CP0_CAUSE(k1)
mfc0 k0, CP0_ENTRYHI
LONG_S k0, VCPU_HOST_ENTRYHI(k1)
/* Now restore the host state just enough to run the handlers */
/* Swtich EBASE to the one used by Linux */
/* load up the host EBASE */
mfc0 v0, CP0_STATUS
.set at
or k0, v0, ST0_BEV
.set noat
mtc0 k0, CP0_STATUS
ehb
LONG_L k0, VCPU_HOST_EBASE(k1)
mtc0 k0,CP0_EBASE
/* Now that the new EBASE has been loaded, unset BEV and KSU_USER */
.set at
and v0, v0, ~(ST0_EXL | KSU_USER | ST0_IE)
or v0, v0, ST0_CU0
.set noat
mtc0 v0, CP0_STATUS
ehb
/* Load up host GP */
LONG_L gp, VCPU_HOST_GP(k1)
/* Need a stack before we can jump to "C" */
LONG_L sp, VCPU_HOST_STACK(k1)
/* Saved host state */
addiu sp,sp, -PT_SIZE
/* XXXKYMA do we need to load the host ASID, maybe not because the
* kernel entries are marked GLOBAL, need to verify
*/
/* Restore host DDATA_LO */
LONG_L k0, PT_HOST_USERLOCAL(sp)
mtc0 k0, CP0_DDATA_LO
/* Restore RDHWR access */
la k0, 0x2000000F
mtc0 k0, CP0_HWRENA
/* Jump to handler */
FEXPORT(__kvm_mips_jump_to_handler)
/* XXXKYMA: not sure if this is safe, how large is the stack?? */
/* Now jump to the kvm_mips_handle_exit() to see if we can deal with this in the kernel */
la t9,kvm_mips_handle_exit
jalr.hb t9
addiu sp,sp, -CALLFRAME_SIZ /* BD Slot */
/* Return from handler Make sure interrupts are disabled */
di
ehb
/* XXXKYMA: k0/k1 could have been blown away if we processed an exception
* while we were handling the exception from the guest, reload k1
*/
move k1, s1
addiu k1, k1, VCPU_HOST_ARCH
/* Check return value, should tell us if we are returning to the host (handle I/O etc)
* or resuming the guest
*/
andi t0, v0, RESUME_HOST
bnez t0, __kvm_mips_return_to_host
nop
__kvm_mips_return_to_guest:
/* Put the saved pointer to vcpu (s1) back into the DDATA_LO Register */
mtc0 s1, CP0_DDATA_LO
/* Load up the Guest EBASE to minimize the window where BEV is set */
LONG_L t0, VCPU_GUEST_EBASE(k1)
/* Switch EBASE back to the one used by KVM */
mfc0 v1, CP0_STATUS
.set at
or k0, v1, ST0_BEV
.set noat
mtc0 k0, CP0_STATUS
ehb
mtc0 t0,CP0_EBASE
/* Setup status register for running guest in UM */
.set at
or v1, v1, (ST0_EXL | KSU_USER | ST0_IE)
and v1, v1, ~ST0_CU0
.set noat
mtc0 v1, CP0_STATUS
ehb
/* Set Guest EPC */
LONG_L t0, VCPU_PC(k1)
mtc0 t0, CP0_EPC
/* Set the ASID for the Guest Kernel */
sll t0, t0, 1 /* with kseg0 @ 0x40000000, kernel */
/* addresses shift to 0x80000000 */
bltz t0, 1f /* If kernel */
addiu t1, k1, VCPU_GUEST_KERNEL_ASID /* (BD) */
addiu t1, k1, VCPU_GUEST_USER_ASID /* else user */
1:
/* t1: contains the base of the ASID array, need to get the cpu id */
LONG_L t2, TI_CPU($28) /* smp_processor_id */
sll t2, t2, 2 /* x4 */
addu t3, t1, t2
LONG_L k0, (t3)
andi k0, k0, 0xff
mtc0 k0,CP0_ENTRYHI
ehb
/* Disable RDHWR access */
mtc0 zero, CP0_HWRENA
/* load the guest context from VCPU and return */
LONG_L $0, VCPU_R0(k1)
LONG_L $1, VCPU_R1(k1)
LONG_L $2, VCPU_R2(k1)
LONG_L $3, VCPU_R3(k1)
LONG_L $4, VCPU_R4(k1)
LONG_L $5, VCPU_R5(k1)
LONG_L $6, VCPU_R6(k1)
LONG_L $7, VCPU_R7(k1)
LONG_L $8, VCPU_R8(k1)
LONG_L $9, VCPU_R9(k1)
LONG_L $10, VCPU_R10(k1)
LONG_L $11, VCPU_R11(k1)
LONG_L $12, VCPU_R12(k1)
LONG_L $13, VCPU_R13(k1)
LONG_L $14, VCPU_R14(k1)
LONG_L $15, VCPU_R15(k1)
LONG_L $16, VCPU_R16(k1)
LONG_L $17, VCPU_R17(k1)
LONG_L $18, VCPU_R18(k1)
LONG_L $19, VCPU_R19(k1)
LONG_L $20, VCPU_R20(k1)
LONG_L $21, VCPU_R21(k1)
LONG_L $22, VCPU_R22(k1)
LONG_L $23, VCPU_R23(k1)
LONG_L $24, VCPU_R24(k1)
LONG_L $25, VCPU_R25(k1)
/* $/k1 loaded later */
LONG_L $28, VCPU_R28(k1)
LONG_L $29, VCPU_R29(k1)
LONG_L $30, VCPU_R30(k1)
LONG_L $31, VCPU_R31(k1)
FEXPORT(__kvm_mips_skip_guest_restore)
LONG_L k0, VCPU_HI(k1)
mthi k0
LONG_L k0, VCPU_LO(k1)
mtlo k0
LONG_L k0, VCPU_R26(k1)
LONG_L k1, VCPU_R27(k1)
eret
__kvm_mips_return_to_host:
/* EBASE is already pointing to Linux */
LONG_L k1, VCPU_HOST_STACK(k1)
addiu k1,k1, -PT_SIZE
/* Restore host DDATA_LO */
LONG_L k0, PT_HOST_USERLOCAL(k1)
mtc0 k0, CP0_DDATA_LO
/* Restore host ASID */
LONG_L k0, PT_HOST_ASID(sp)
andi k0, 0xff
mtc0 k0,CP0_ENTRYHI
ehb
/* Load context saved on the host stack */
LONG_L $0, PT_R0(k1)
LONG_L $1, PT_R1(k1)
/* r2/v0 is the return code, shift it down by 2 (arithmetic) to recover the err code */
sra k0, v0, 2
move $2, k0
LONG_L $3, PT_R3(k1)
LONG_L $4, PT_R4(k1)
LONG_L $5, PT_R5(k1)
LONG_L $6, PT_R6(k1)
LONG_L $7, PT_R7(k1)
LONG_L $8, PT_R8(k1)
LONG_L $9, PT_R9(k1)
LONG_L $10, PT_R10(k1)
LONG_L $11, PT_R11(k1)
LONG_L $12, PT_R12(k1)
LONG_L $13, PT_R13(k1)
LONG_L $14, PT_R14(k1)
LONG_L $15, PT_R15(k1)
LONG_L $16, PT_R16(k1)
LONG_L $17, PT_R17(k1)
LONG_L $18, PT_R18(k1)
LONG_L $19, PT_R19(k1)
LONG_L $20, PT_R20(k1)
LONG_L $21, PT_R21(k1)
LONG_L $22, PT_R22(k1)
LONG_L $23, PT_R23(k1)
LONG_L $24, PT_R24(k1)
LONG_L $25, PT_R25(k1)
/* Host k0/k1 were not saved */
LONG_L $28, PT_R28(k1)
LONG_L $29, PT_R29(k1)
LONG_L $30, PT_R30(k1)
LONG_L k0, PT_HI(k1)
mthi k0
LONG_L k0, PT_LO(k1)
mtlo k0
/* Restore RDHWR access */
la k0, 0x2000000F
mtc0 k0, CP0_HWRENA
/* Restore RA, which is the address we will return to */
LONG_L ra, PT_R31(k1)
j ra
nop
.set pop
VECTOR_END(MIPSX(GuestExceptionEnd))
.end MIPSX(GuestException)
MIPSX(exceptions):
####
##### The exception handlers.
#####
.word _C_LABEL(MIPSX(GuestException)) # 0
.word _C_LABEL(MIPSX(GuestException)) # 1
.word _C_LABEL(MIPSX(GuestException)) # 2
.word _C_LABEL(MIPSX(GuestException)) # 3
.word _C_LABEL(MIPSX(GuestException)) # 4
.word _C_LABEL(MIPSX(GuestException)) # 5
.word _C_LABEL(MIPSX(GuestException)) # 6
.word _C_LABEL(MIPSX(GuestException)) # 7
.word _C_LABEL(MIPSX(GuestException)) # 8
.word _C_LABEL(MIPSX(GuestException)) # 9
.word _C_LABEL(MIPSX(GuestException)) # 10
.word _C_LABEL(MIPSX(GuestException)) # 11
.word _C_LABEL(MIPSX(GuestException)) # 12
.word _C_LABEL(MIPSX(GuestException)) # 13
.word _C_LABEL(MIPSX(GuestException)) # 14
.word _C_LABEL(MIPSX(GuestException)) # 15
.word _C_LABEL(MIPSX(GuestException)) # 16
.word _C_LABEL(MIPSX(GuestException)) # 17
.word _C_LABEL(MIPSX(GuestException)) # 18
.word _C_LABEL(MIPSX(GuestException)) # 19
.word _C_LABEL(MIPSX(GuestException)) # 20
.word _C_LABEL(MIPSX(GuestException)) # 21
.word _C_LABEL(MIPSX(GuestException)) # 22
.word _C_LABEL(MIPSX(GuestException)) # 23
.word _C_LABEL(MIPSX(GuestException)) # 24
.word _C_LABEL(MIPSX(GuestException)) # 25
.word _C_LABEL(MIPSX(GuestException)) # 26
.word _C_LABEL(MIPSX(GuestException)) # 27
.word _C_LABEL(MIPSX(GuestException)) # 28
.word _C_LABEL(MIPSX(GuestException)) # 29
.word _C_LABEL(MIPSX(GuestException)) # 30
.word _C_LABEL(MIPSX(GuestException)) # 31
/* This routine makes changes to the instruction stream effective to the hardware.
* It should be called after the instruction stream is written.
* On return, the new instructions are effective.
* Inputs:
* a0 = Start address of new instruction stream
* a1 = Size, in bytes, of new instruction stream
*/
#define HW_SYNCI_Step $1
LEAF(MIPSX(SyncICache))
.set push
.set mips32r2
beq a1, zero, 20f
nop
addu a1, a0, a1
rdhwr v0, HW_SYNCI_Step
beq v0, zero, 20f
nop
10:
synci 0(a0)
addu a0, a0, v0
sltu v1, a0, a1
bne v1, zero, 10b
nop
sync
20:
jr.hb ra
nop
.set pop
END(MIPSX(SyncICache))