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Add SLB switching code for entry/exit

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This is the really low level of guest entry/exit code.

Book3s_64 has an SLB, which stores all ESID -> VSID mappings we're
currently aware of.

The segments in the guest differ from the ones on the host, so we need
to switch the SLB to tell the MMU that we're in a new context.

So we store a shadow of the guest's SLB in the PACA, switch to that on
entry and only restore bolted entries on exit, leaving the rest to the
Linux SLB fault handler.

That way we get a really clean way of switching the SLB.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Alexander Graf 2009-11-02 12:02:29 +00:00 committed by Benjamin Herrenschmidt
parent 29eb61bca1
commit 5126ed3760
1 changed files with 262 additions and 0 deletions
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262
arch/powerpc/kvm/book3s_64_slb.S Normal file
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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 SUSE Linux Products GmbH 2009
*
* Authors: Alexander Graf <agraf@suse.de>
*/
#define SHADOW_SLB_ESID(num) (SLBSHADOW_SAVEAREA + (num * 0x10))
#define SHADOW_SLB_VSID(num) (SLBSHADOW_SAVEAREA + (num * 0x10) + 0x8)
#define UNBOLT_SLB_ENTRY(num) \
ld r9, SHADOW_SLB_ESID(num)(r12); \
/* Invalid? Skip. */; \
rldicl. r0, r9, 37, 63; \
beq slb_entry_skip_ ## num; \
xoris r9, r9, SLB_ESID_V@h; \
std r9, SHADOW_SLB_ESID(num)(r12); \
slb_entry_skip_ ## num:
#define REBOLT_SLB_ENTRY(num) \
ld r10, SHADOW_SLB_ESID(num)(r11); \
cmpdi r10, 0; \
beq slb_exit_skip_1; \
oris r10, r10, SLB_ESID_V@h; \
ld r9, SHADOW_SLB_VSID(num)(r11); \
slbmte r9, r10; \
std r10, SHADOW_SLB_ESID(num)(r11); \
slb_exit_skip_ ## num:
/******************************************************************************
* *
* Entry code *
* *
*****************************************************************************/
.global kvmppc_handler_trampoline_enter
kvmppc_handler_trampoline_enter:
/* Required state:
*
* MSR = ~IR|DR
* R13 = PACA
* R9 = guest IP
* R10 = guest MSR
* R11 = free
* R12 = free
* PACA[PACA_EXMC + EX_R9] = guest R9
* PACA[PACA_EXMC + EX_R10] = guest R10
* PACA[PACA_EXMC + EX_R11] = guest R11
* PACA[PACA_EXMC + EX_R12] = guest R12
* PACA[PACA_EXMC + EX_R13] = guest R13
* PACA[PACA_EXMC + EX_CCR] = guest CR
* PACA[PACA_EXMC + EX_R3] = guest XER
*/
mtsrr0 r9
mtsrr1 r10
mtspr SPRN_SPRG_SCRATCH0, r0
/* Remove LPAR shadow entries */
#if SLB_NUM_BOLTED == 3
ld r12, PACA_SLBSHADOWPTR(r13)
/* Save off the first entry so we can slbie it later */
ld r10, SHADOW_SLB_ESID(0)(r12)
ld r11, SHADOW_SLB_VSID(0)(r12)
/* Remove bolted entries */
UNBOLT_SLB_ENTRY(0)
UNBOLT_SLB_ENTRY(1)
UNBOLT_SLB_ENTRY(2)
#else
#error unknown number of bolted entries
#endif
/* Flush SLB */
slbia
/* r0 = esid & ESID_MASK */
rldicr r10, r10, 0, 35
/* r0 |= CLASS_BIT(VSID) */
rldic r12, r11, 56 - 36, 36
or r10, r10, r12
slbie r10
isync
/* Fill SLB with our shadow */
lbz r12, PACA_KVM_SLB_MAX(r13)
mulli r12, r12, 16
addi r12, r12, PACA_KVM_SLB
add r12, r12, r13
/* for (r11 = kvm_slb; r11 < kvm_slb + kvm_slb_size; r11+=slb_entry) */
li r11, PACA_KVM_SLB
add r11, r11, r13
slb_loop_enter:
ld r10, 0(r11)
rldicl. r0, r10, 37, 63
beq slb_loop_enter_skip
ld r9, 8(r11)
slbmte r9, r10
slb_loop_enter_skip:
addi r11, r11, 16
cmpd cr0, r11, r12
blt slb_loop_enter
slb_do_enter:
/* Enter guest */
mfspr r0, SPRN_SPRG_SCRATCH0
ld r9, (PACA_EXMC+EX_R9)(r13)
ld r10, (PACA_EXMC+EX_R10)(r13)
ld r12, (PACA_EXMC+EX_R12)(r13)
lwz r11, (PACA_EXMC+EX_CCR)(r13)
mtcr r11
ld r11, (PACA_EXMC+EX_R3)(r13)
mtxer r11
ld r11, (PACA_EXMC+EX_R11)(r13)
ld r13, (PACA_EXMC+EX_R13)(r13)
RFI
kvmppc_handler_trampoline_enter_end:
/******************************************************************************
* *
* Exit code *
* *
*****************************************************************************/
.global kvmppc_handler_trampoline_exit
kvmppc_handler_trampoline_exit:
/* Register usage at this point:
*
* SPRG_SCRATCH0 = guest R13
* R01 = host R1
* R02 = host R2
* R10 = guest PC
* R11 = guest MSR
* R12 = exit handler id
* R13 = PACA
* PACA.exmc.CCR = guest CR
* PACA.exmc.R9 = guest R1
* PACA.exmc.R10 = guest R10
* PACA.exmc.R11 = guest R11
* PACA.exmc.R12 = guest R12
* PACA.exmc.R13 = guest R2
*
*/
/* Save registers */
std r0, (PACA_EXMC+EX_SRR0)(r13)
std r9, (PACA_EXMC+EX_R3)(r13)
std r10, (PACA_EXMC+EX_LR)(r13)
std r11, (PACA_EXMC+EX_DAR)(r13)
/*
* In order for us to easily get the last instruction,
* we got the #vmexit at, we exploit the fact that the
* virtual layout is still the same here, so we can just
* ld from the guest's PC address
*/
/* We only load the last instruction when it's safe */
cmpwi r12, BOOK3S_INTERRUPT_DATA_STORAGE
beq ld_last_inst
cmpwi r12, BOOK3S_INTERRUPT_PROGRAM
beq ld_last_inst
b no_ld_last_inst
ld_last_inst:
/* Save off the guest instruction we're at */
/* 1) enable paging for data */
mfmsr r9
ori r11, r9, MSR_DR /* Enable paging for data */
mtmsr r11
/* 2) fetch the instruction */
lwz r0, 0(r10)
/* 3) disable paging again */
mtmsr r9
no_ld_last_inst:
/* Restore bolted entries from the shadow and fix it along the way */
/* We don't store anything in entry 0, so we don't need to take care of it */
slbia
isync
#if SLB_NUM_BOLTED == 3
ld r11, PACA_SLBSHADOWPTR(r13)
REBOLT_SLB_ENTRY(0)
REBOLT_SLB_ENTRY(1)
REBOLT_SLB_ENTRY(2)
#else
#error unknown number of bolted entries
#endif
slb_do_exit:
/* Restore registers */
ld r11, (PACA_EXMC+EX_DAR)(r13)
ld r10, (PACA_EXMC+EX_LR)(r13)
ld r9, (PACA_EXMC+EX_R3)(r13)
/* Save last inst */
stw r0, (PACA_EXMC+EX_LR)(r13)
/* Save DAR and DSISR before going to paged mode */
mfdar r0
std r0, (PACA_EXMC+EX_DAR)(r13)
mfdsisr r0
stw r0, (PACA_EXMC+EX_DSISR)(r13)
/* RFI into the highmem handler */
mfmsr r0
ori r0, r0, MSR_IR|MSR_DR|MSR_RI /* Enable paging */
mtsrr1 r0
ld r0, PACASAVEDMSR(r13) /* Highmem handler address */
mtsrr0 r0
mfspr r0, SPRN_SPRG_SCRATCH0
RFI
kvmppc_handler_trampoline_exit_end: