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linux/arch/powerpc/kvm/booke_interrupts.S
Hollis Blanchard 49dd2c4928 KVM: powerpc: Map guest userspace with TID=0 mappings 
When we use TID=N userspace mappings, we must ensure that kernel mappings have
been destroyed when entering userspace. Using TID=1/TID=0 for kernel/user
mappings and running userspace with PID=0 means that userspace can't access the
kernel mappings, but the kernel can directly access userspace.

The net is that we don't need to flush the TLB on privilege switches, but we do
on guest context switches (which are far more infrequent). Guest boot time
performance improvement: about 30%.

Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
2008-10-15 10:15:16 +02:00

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/*
* 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 IBM Corp. 2007
*
* Authors: Hollis Blanchard <hollisb@us.ibm.com>
*/
#include <asm/ppc_asm.h>
#include <asm/kvm_asm.h>
#include <asm/reg.h>
#include <asm/mmu-44x.h>
#include <asm/page.h>
#include <asm/asm-offsets.h>
#define KVMPPC_MSR_MASK (MSR_CE|MSR_EE|MSR_PR|MSR_DE|MSR_ME|MSR_IS|MSR_DS)
#define VCPU_GPR(n) (VCPU_GPRS + (n * 4))
/* The host stack layout: */
#define HOST_R1 0 /* Implied by stwu. */
#define HOST_CALLEE_LR 4
#define HOST_RUN 8
/* r2 is special: it holds 'current', and it made nonvolatile in the
* kernel with the -ffixed-r2 gcc option. */
#define HOST_R2 12
#define HOST_NV_GPRS 16
#define HOST_NV_GPR(n) (HOST_NV_GPRS + ((n - 14) * 4))
#define HOST_MIN_STACK_SIZE (HOST_NV_GPR(31) + 4)
#define HOST_STACK_SIZE (((HOST_MIN_STACK_SIZE + 15) / 16) * 16) /* Align. */
#define HOST_STACK_LR (HOST_STACK_SIZE + 4) /* In caller stack frame. */
#define NEED_INST_MASK ((1<<BOOKE_INTERRUPT_PROGRAM) | \
(1<<BOOKE_INTERRUPT_DTLB_MISS) | \
(1<<BOOKE_INTERRUPT_DEBUG))
#define NEED_DEAR_MASK ((1<<BOOKE_INTERRUPT_DATA_STORAGE) | \
(1<<BOOKE_INTERRUPT_DTLB_MISS))
#define NEED_ESR_MASK ((1<<BOOKE_INTERRUPT_DATA_STORAGE) | \
(1<<BOOKE_INTERRUPT_INST_STORAGE) | \
(1<<BOOKE_INTERRUPT_PROGRAM) | \
(1<<BOOKE_INTERRUPT_DTLB_MISS))
.macro KVM_HANDLER ivor_nr
_GLOBAL(kvmppc_handler_\ivor_nr)
/* Get pointer to vcpu and record exit number. */
mtspr SPRN_SPRG0, r4
mfspr r4, SPRN_SPRG1
stw r5, VCPU_GPR(r5)(r4)
stw r6, VCPU_GPR(r6)(r4)
mfctr r5
lis r6, kvmppc_resume_host@h
stw r5, VCPU_CTR(r4)
li r5, \ivor_nr
ori r6, r6, kvmppc_resume_host@l
mtctr r6
bctr
.endm
_GLOBAL(kvmppc_handlers_start)
KVM_HANDLER BOOKE_INTERRUPT_CRITICAL
KVM_HANDLER BOOKE_INTERRUPT_MACHINE_CHECK
KVM_HANDLER BOOKE_INTERRUPT_DATA_STORAGE
KVM_HANDLER BOOKE_INTERRUPT_INST_STORAGE
KVM_HANDLER BOOKE_INTERRUPT_EXTERNAL
KVM_HANDLER BOOKE_INTERRUPT_ALIGNMENT
KVM_HANDLER BOOKE_INTERRUPT_PROGRAM
KVM_HANDLER BOOKE_INTERRUPT_FP_UNAVAIL
KVM_HANDLER BOOKE_INTERRUPT_SYSCALL
KVM_HANDLER BOOKE_INTERRUPT_AP_UNAVAIL
KVM_HANDLER BOOKE_INTERRUPT_DECREMENTER
KVM_HANDLER BOOKE_INTERRUPT_FIT
KVM_HANDLER BOOKE_INTERRUPT_WATCHDOG
KVM_HANDLER BOOKE_INTERRUPT_DTLB_MISS
KVM_HANDLER BOOKE_INTERRUPT_ITLB_MISS
KVM_HANDLER BOOKE_INTERRUPT_DEBUG
_GLOBAL(kvmppc_handler_len)
.long kvmppc_handler_1 - kvmppc_handler_0
/* Registers:
* SPRG0: guest r4
* r4: vcpu pointer
* r5: KVM exit number
*/
_GLOBAL(kvmppc_resume_host)
stw r3, VCPU_GPR(r3)(r4)
mfcr r3
stw r3, VCPU_CR(r4)
stw r7, VCPU_GPR(r7)(r4)
stw r8, VCPU_GPR(r8)(r4)
stw r9, VCPU_GPR(r9)(r4)
li r6, 1
slw r6, r6, r5
/* Save the faulting instruction and all GPRs for emulation. */
andi. r7, r6, NEED_INST_MASK
beq ..skip_inst_copy
mfspr r9, SPRN_SRR0
mfmsr r8
ori r7, r8, MSR_DS
mtmsr r7
isync
lwz r9, 0(r9)
mtmsr r8
isync
stw r9, VCPU_LAST_INST(r4)
stw r15, VCPU_GPR(r15)(r4)
stw r16, VCPU_GPR(r16)(r4)
stw r17, VCPU_GPR(r17)(r4)
stw r18, VCPU_GPR(r18)(r4)
stw r19, VCPU_GPR(r19)(r4)
stw r20, VCPU_GPR(r20)(r4)
stw r21, VCPU_GPR(r21)(r4)
stw r22, VCPU_GPR(r22)(r4)
stw r23, VCPU_GPR(r23)(r4)
stw r24, VCPU_GPR(r24)(r4)
stw r25, VCPU_GPR(r25)(r4)
stw r26, VCPU_GPR(r26)(r4)
stw r27, VCPU_GPR(r27)(r4)
stw r28, VCPU_GPR(r28)(r4)
stw r29, VCPU_GPR(r29)(r4)
stw r30, VCPU_GPR(r30)(r4)
stw r31, VCPU_GPR(r31)(r4)
..skip_inst_copy:
/* Also grab DEAR and ESR before the host can clobber them. */
andi. r7, r6, NEED_DEAR_MASK
beq ..skip_dear
mfspr r9, SPRN_DEAR
stw r9, VCPU_FAULT_DEAR(r4)
..skip_dear:
andi. r7, r6, NEED_ESR_MASK
beq ..skip_esr
mfspr r9, SPRN_ESR
stw r9, VCPU_FAULT_ESR(r4)
..skip_esr:
/* Save remaining volatile guest register state to vcpu. */
stw r0, VCPU_GPR(r0)(r4)
stw r1, VCPU_GPR(r1)(r4)
stw r2, VCPU_GPR(r2)(r4)
stw r10, VCPU_GPR(r10)(r4)
stw r11, VCPU_GPR(r11)(r4)
stw r12, VCPU_GPR(r12)(r4)
stw r13, VCPU_GPR(r13)(r4)
stw r14, VCPU_GPR(r14)(r4) /* We need a NV GPR below. */
mflr r3
stw r3, VCPU_LR(r4)
mfxer r3
stw r3, VCPU_XER(r4)
mfspr r3, SPRN_SPRG0
stw r3, VCPU_GPR(r4)(r4)
mfspr r3, SPRN_SRR0
stw r3, VCPU_PC(r4)
/* Restore host stack pointer and PID before IVPR, since the host
* exception handlers use them. */
lwz r1, VCPU_HOST_STACK(r4)
lwz r3, VCPU_HOST_PID(r4)
mtspr SPRN_PID, r3
/* Restore host IVPR before re-enabling interrupts. We cheat and know
* that Linux IVPR is always 0xc0000000. */
lis r3, 0xc000
mtspr SPRN_IVPR, r3
/* Switch to kernel stack and jump to handler. */
LOAD_REG_ADDR(r3, kvmppc_handle_exit)
mtctr r3
lwz r3, HOST_RUN(r1)
lwz r2, HOST_R2(r1)
mr r14, r4 /* Save vcpu pointer. */
bctrl /* kvmppc_handle_exit() */
/* Restore vcpu pointer and the nonvolatiles we used. */
mr r4, r14
lwz r14, VCPU_GPR(r14)(r4)
/* Sometimes instruction emulation must restore complete GPR state. */
andi. r5, r3, RESUME_FLAG_NV
beq ..skip_nv_load
lwz r15, VCPU_GPR(r15)(r4)
lwz r16, VCPU_GPR(r16)(r4)
lwz r17, VCPU_GPR(r17)(r4)
lwz r18, VCPU_GPR(r18)(r4)
lwz r19, VCPU_GPR(r19)(r4)
lwz r20, VCPU_GPR(r20)(r4)
lwz r21, VCPU_GPR(r21)(r4)
lwz r22, VCPU_GPR(r22)(r4)
lwz r23, VCPU_GPR(r23)(r4)
lwz r24, VCPU_GPR(r24)(r4)
lwz r25, VCPU_GPR(r25)(r4)
lwz r26, VCPU_GPR(r26)(r4)
lwz r27, VCPU_GPR(r27)(r4)
lwz r28, VCPU_GPR(r28)(r4)
lwz r29, VCPU_GPR(r29)(r4)
lwz r30, VCPU_GPR(r30)(r4)
lwz r31, VCPU_GPR(r31)(r4)
..skip_nv_load:
/* Should we return to the guest? */
andi. r5, r3, RESUME_FLAG_HOST
beq lightweight_exit
srawi r3, r3, 2 /* Shift -ERR back down. */
heavyweight_exit:
/* Not returning to guest. */
/* We already saved guest volatile register state; now save the
* non-volatiles. */
stw r15, VCPU_GPR(r15)(r4)
stw r16, VCPU_GPR(r16)(r4)
stw r17, VCPU_GPR(r17)(r4)
stw r18, VCPU_GPR(r18)(r4)
stw r19, VCPU_GPR(r19)(r4)
stw r20, VCPU_GPR(r20)(r4)
stw r21, VCPU_GPR(r21)(r4)
stw r22, VCPU_GPR(r22)(r4)
stw r23, VCPU_GPR(r23)(r4)
stw r24, VCPU_GPR(r24)(r4)
stw r25, VCPU_GPR(r25)(r4)
stw r26, VCPU_GPR(r26)(r4)
stw r27, VCPU_GPR(r27)(r4)
stw r28, VCPU_GPR(r28)(r4)
stw r29, VCPU_GPR(r29)(r4)
stw r30, VCPU_GPR(r30)(r4)
stw r31, VCPU_GPR(r31)(r4)
/* Load host non-volatile register state from host stack. */
lwz r14, HOST_NV_GPR(r14)(r1)
lwz r15, HOST_NV_GPR(r15)(r1)
lwz r16, HOST_NV_GPR(r16)(r1)
lwz r17, HOST_NV_GPR(r17)(r1)
lwz r18, HOST_NV_GPR(r18)(r1)
lwz r19, HOST_NV_GPR(r19)(r1)
lwz r20, HOST_NV_GPR(r20)(r1)
lwz r21, HOST_NV_GPR(r21)(r1)
lwz r22, HOST_NV_GPR(r22)(r1)
lwz r23, HOST_NV_GPR(r23)(r1)
lwz r24, HOST_NV_GPR(r24)(r1)
lwz r25, HOST_NV_GPR(r25)(r1)
lwz r26, HOST_NV_GPR(r26)(r1)
lwz r27, HOST_NV_GPR(r27)(r1)
lwz r28, HOST_NV_GPR(r28)(r1)
lwz r29, HOST_NV_GPR(r29)(r1)
lwz r30, HOST_NV_GPR(r30)(r1)
lwz r31, HOST_NV_GPR(r31)(r1)
/* Return to kvm_vcpu_run(). */
lwz r4, HOST_STACK_LR(r1)
addi r1, r1, HOST_STACK_SIZE
mtlr r4
/* r3 still contains the return code from kvmppc_handle_exit(). */
blr
/* Registers:
* r3: kvm_run pointer
* r4: vcpu pointer
*/
_GLOBAL(__kvmppc_vcpu_run)
stwu r1, -HOST_STACK_SIZE(r1)
stw r1, VCPU_HOST_STACK(r4) /* Save stack pointer to vcpu. */
/* Save host state to stack. */
stw r3, HOST_RUN(r1)
mflr r3
stw r3, HOST_STACK_LR(r1)
/* Save host non-volatile register state to stack. */
stw r14, HOST_NV_GPR(r14)(r1)
stw r15, HOST_NV_GPR(r15)(r1)
stw r16, HOST_NV_GPR(r16)(r1)
stw r17, HOST_NV_GPR(r17)(r1)
stw r18, HOST_NV_GPR(r18)(r1)
stw r19, HOST_NV_GPR(r19)(r1)
stw r20, HOST_NV_GPR(r20)(r1)
stw r21, HOST_NV_GPR(r21)(r1)
stw r22, HOST_NV_GPR(r22)(r1)
stw r23, HOST_NV_GPR(r23)(r1)
stw r24, HOST_NV_GPR(r24)(r1)
stw r25, HOST_NV_GPR(r25)(r1)
stw r26, HOST_NV_GPR(r26)(r1)
stw r27, HOST_NV_GPR(r27)(r1)
stw r28, HOST_NV_GPR(r28)(r1)
stw r29, HOST_NV_GPR(r29)(r1)
stw r30, HOST_NV_GPR(r30)(r1)
stw r31, HOST_NV_GPR(r31)(r1)
/* Load guest non-volatiles. */
lwz r14, VCPU_GPR(r14)(r4)
lwz r15, VCPU_GPR(r15)(r4)
lwz r16, VCPU_GPR(r16)(r4)
lwz r17, VCPU_GPR(r17)(r4)
lwz r18, VCPU_GPR(r18)(r4)
lwz r19, VCPU_GPR(r19)(r4)
lwz r20, VCPU_GPR(r20)(r4)
lwz r21, VCPU_GPR(r21)(r4)
lwz r22, VCPU_GPR(r22)(r4)
lwz r23, VCPU_GPR(r23)(r4)
lwz r24, VCPU_GPR(r24)(r4)
lwz r25, VCPU_GPR(r25)(r4)
lwz r26, VCPU_GPR(r26)(r4)
lwz r27, VCPU_GPR(r27)(r4)
lwz r28, VCPU_GPR(r28)(r4)
lwz r29, VCPU_GPR(r29)(r4)
lwz r30, VCPU_GPR(r30)(r4)
lwz r31, VCPU_GPR(r31)(r4)
lightweight_exit:
stw r2, HOST_R2(r1)
mfspr r3, SPRN_PID
stw r3, VCPU_HOST_PID(r4)
lwz r3, VCPU_SHADOW_PID(r4)
mtspr SPRN_PID, r3
/* Prevent all asynchronous TLB updates. */
mfmsr r5
lis r6, (MSR_EE|MSR_CE|MSR_ME|MSR_DE)@h
ori r6, r6, (MSR_EE|MSR_CE|MSR_ME|MSR_DE)@l
andc r6, r5, r6
mtmsr r6
/* Load the guest mappings, leaving the host's "pinned" kernel mappings
* in place. */
mfspr r10, SPRN_MMUCR /* Save host MMUCR. */
li r5, PPC44x_TLB_SIZE
lis r5, tlb_44x_hwater@ha
lwz r5, tlb_44x_hwater@l(r5)
mtctr r5
addi r9, r4, VCPU_SHADOW_TLB
addi r5, r4, VCPU_SHADOW_MOD
li r3, 0
1:
lbzx r7, r3, r5
cmpwi r7, 0
beq 3f
/* Load guest entry. */
mulli r11, r3, TLBE_BYTES
add r11, r11, r9
lwz r7, 0(r11)
mtspr SPRN_MMUCR, r7
lwz r7, 4(r11)
tlbwe r7, r3, PPC44x_TLB_PAGEID
lwz r7, 8(r11)
tlbwe r7, r3, PPC44x_TLB_XLAT
lwz r7, 12(r11)
tlbwe r7, r3, PPC44x_TLB_ATTRIB
3:
addi r3, r3, 1 /* Increment index. */
bdnz 1b
mtspr SPRN_MMUCR, r10 /* Restore host MMUCR. */
/* Clear bitmap of modified TLB entries */
li r5, PPC44x_TLB_SIZE>>2
mtctr r5
addi r5, r4, VCPU_SHADOW_MOD - 4
li r6, 0
1:
stwu r6, 4(r5)
bdnz 1b
iccci 0, 0 /* XXX hack */
/* Load some guest volatiles. */
lwz r0, VCPU_GPR(r0)(r4)
lwz r2, VCPU_GPR(r2)(r4)
lwz r9, VCPU_GPR(r9)(r4)
lwz r10, VCPU_GPR(r10)(r4)
lwz r11, VCPU_GPR(r11)(r4)
lwz r12, VCPU_GPR(r12)(r4)
lwz r13, VCPU_GPR(r13)(r4)
lwz r3, VCPU_LR(r4)
mtlr r3
lwz r3, VCPU_XER(r4)
mtxer r3
/* Switch the IVPR. XXX If we take a TLB miss after this we're screwed,
* so how do we make sure vcpu won't fault? */
lis r8, kvmppc_booke_handlers@ha
lwz r8, kvmppc_booke_handlers@l(r8)
mtspr SPRN_IVPR, r8
/* Save vcpu pointer for the exception handlers. */
mtspr SPRN_SPRG1, r4
/* Can't switch the stack pointer until after IVPR is switched,
* because host interrupt handlers would get confused. */
lwz r1, VCPU_GPR(r1)(r4)
/* XXX handle USPRG0 */
/* Host interrupt handlers may have clobbered these guest-readable
* SPRGs, so we need to reload them here with the guest's values. */
lwz r3, VCPU_SPRG4(r4)
mtspr SPRN_SPRG4, r3
lwz r3, VCPU_SPRG5(r4)
mtspr SPRN_SPRG5, r3
lwz r3, VCPU_SPRG6(r4)
mtspr SPRN_SPRG6, r3
lwz r3, VCPU_SPRG7(r4)
mtspr SPRN_SPRG7, r3
/* Finish loading guest volatiles and jump to guest. */
lwz r3, VCPU_CTR(r4)
mtctr r3
lwz r3, VCPU_CR(r4)
mtcr r3
lwz r5, VCPU_GPR(r5)(r4)
lwz r6, VCPU_GPR(r6)(r4)
lwz r7, VCPU_GPR(r7)(r4)
lwz r8, VCPU_GPR(r8)(r4)
lwz r3, VCPU_PC(r4)
mtsrr0 r3
lwz r3, VCPU_MSR(r4)
oris r3, r3, KVMPPC_MSR_MASK@h
ori r3, r3, KVMPPC_MSR_MASK@l
mtsrr1 r3
/* Clear any debug events which occurred since we disabled MSR[DE].
* XXX This gives us a 3-instruction window in which a breakpoint
* intended for guest context could fire in the host instead. */
lis r3, 0xffff
ori r3, r3, 0xffff
mtspr SPRN_DBSR, r3
lwz r3, VCPU_GPR(r3)(r4)
lwz r4, VCPU_GPR(r4)(r4)
rfi
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