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linux/arch/powerpc/kvm/book3s_rmhandlers.S
Paul Mackerras 0214394760 KVM: PPC: book3s_pr: Simplify transitions between virtual and real mode 
This simplifies the way that the book3s_pr makes the transition to
real mode when entering the guest.  We now call kvmppc_entry_trampoline
(renamed from kvmppc_rmcall) in the base kernel using a normal function
call instead of doing an indirect call through a pointer in the vcpu.
If kvm is a module, the module loader takes care of generating a
trampoline as it does for other calls to functions outside the module.

kvmppc_entry_trampoline then disables interrupts and jumps to
kvmppc_handler_trampoline_enter in real mode using an rfi[d].
That then uses the link register as the address to return to
(potentially in module space) when the guest exits.

This also simplifies the way that we call the Linux interrupt handler
when we exit the guest due to an external, decrementer or performance
monitor interrupt.  Instead of turning on the MMU, then deciding that
we need to call the Linux handler and turning the MMU back off again,
we now go straight to the handler at the point where we would turn the
MMU on.  The handler will then return to the virtual-mode code
(potentially in the module).

Along the way, this moves the setting and clearing of the HID5 DCBZ32
bit into real-mode interrupts-off code, and also makes sure that
we clear the MSR[RI] bit before loading values into SRR0/1.

The net result is that we no longer need any code addresses to be
stored in vcpu->arch.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
2011-09-25 19:52:29 +03:00

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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 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/mmu.h>
#include <asm/page.h>
#include <asm/asm-offsets.h>
#ifdef CONFIG_PPC_BOOK3S_64
#include <asm/exception-64s.h>
#endif
/*****************************************************************************
* *
* Real Mode handlers that need to be in low physical memory *
* *
****************************************************************************/
#if defined(CONFIG_PPC_BOOK3S_64)
#define FUNC(name) GLUE(.,name)
#define MTMSR_EERI(reg) mtmsrd (reg),1
.globl kvmppc_skip_interrupt
kvmppc_skip_interrupt:
/*
* Here all GPRs are unchanged from when the interrupt happened
* except for r13, which is saved in SPRG_SCRATCH0.
*/
mfspr r13, SPRN_SRR0
addi r13, r13, 4
mtspr SPRN_SRR0, r13
GET_SCRATCH0(r13)
rfid
b .
.globl kvmppc_skip_Hinterrupt
kvmppc_skip_Hinterrupt:
/*
* Here all GPRs are unchanged from when the interrupt happened
* except for r13, which is saved in SPRG_SCRATCH0.
*/
mfspr r13, SPRN_HSRR0
addi r13, r13, 4
mtspr SPRN_HSRR0, r13
GET_SCRATCH0(r13)
hrfid
b .
#elif defined(CONFIG_PPC_BOOK3S_32)
#define FUNC(name) name
#define MTMSR_EERI(reg) mtmsr (reg)
.macro INTERRUPT_TRAMPOLINE intno
.global kvmppc_trampoline_\intno
kvmppc_trampoline_\intno:
mtspr SPRN_SPRG_SCRATCH0, r13 /* Save r13 */
/*
* First thing to do is to find out if we're coming
* from a KVM guest or a Linux process.
*
* To distinguish, we check a magic byte in the PACA/current
*/
mfspr r13, SPRN_SPRG_THREAD
lwz r13, THREAD_KVM_SVCPU(r13)
/* PPC32 can have a NULL pointer - let's check for that */
mtspr SPRN_SPRG_SCRATCH1, r12 /* Save r12 */
mfcr r12
cmpwi r13, 0
bne 1f
2: mtcr r12
mfspr r12, SPRN_SPRG_SCRATCH1
mfspr r13, SPRN_SPRG_SCRATCH0 /* r13 = original r13 */
b kvmppc_resume_\intno /* Get back original handler */
1: tophys(r13, r13)
stw r12, HSTATE_SCRATCH1(r13)
mfspr r12, SPRN_SPRG_SCRATCH1
stw r12, HSTATE_SCRATCH0(r13)
lbz r12, HSTATE_IN_GUEST(r13)
cmpwi r12, KVM_GUEST_MODE_NONE
bne ..kvmppc_handler_hasmagic_\intno
/* No KVM guest? Then jump back to the Linux handler! */
lwz r12, HSTATE_SCRATCH1(r13)
b 2b
/* Now we know we're handling a KVM guest */
..kvmppc_handler_hasmagic_\intno:
/* Should we just skip the faulting instruction? */
cmpwi r12, KVM_GUEST_MODE_SKIP
beq kvmppc_handler_skip_ins
/* Let's store which interrupt we're handling */
li r12, \intno
/* Jump into the SLB exit code that goes to the highmem handler */
b kvmppc_handler_trampoline_exit
.endm
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_SYSTEM_RESET
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_MACHINE_CHECK
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_DATA_STORAGE
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_INST_STORAGE
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_EXTERNAL
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_ALIGNMENT
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_PROGRAM
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_FP_UNAVAIL
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_DECREMENTER
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_SYSCALL
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_TRACE
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_PERFMON
INTERRUPT_TRAMPOLINE BOOK3S_INTERRUPT_ALTIVEC
/*
* Bring us back to the faulting code, but skip the
* faulting instruction.
*
* This is a generic exit path from the interrupt
* trampolines above.
*
* Input Registers:
*
* R12 = free
* R13 = Shadow VCPU (PACA)
* HSTATE.SCRATCH0 = guest R12
* HSTATE.SCRATCH1 = guest CR
* SPRG_SCRATCH0 = guest R13
*
*/
kvmppc_handler_skip_ins:
/* Patch the IP to the next instruction */
mfsrr0 r12
addi r12, r12, 4
mtsrr0 r12
/* Clean up all state */
lwz r12, HSTATE_SCRATCH1(r13)
mtcr r12
PPC_LL r12, HSTATE_SCRATCH0(r13)
GET_SCRATCH0(r13)
/* And get back into the code */
RFI
#endif
/*
* Call kvmppc_handler_trampoline_enter in real mode
*
* On entry, r4 contains the guest shadow MSR
*/
_GLOBAL(kvmppc_entry_trampoline)
mfmsr r5
LOAD_REG_ADDR(r7, kvmppc_handler_trampoline_enter)
toreal(r7)
li r9, MSR_RI
ori r9, r9, MSR_EE
andc r9, r5, r9 /* Clear EE and RI in MSR value */
li r6, MSR_IR | MSR_DR
ori r6, r6, MSR_EE
andc r6, r5, r6 /* Clear EE, DR and IR in MSR value */
MTMSR_EERI(r9) /* Clear EE and RI in MSR */
mtsrr0 r7 /* before we set srr0/1 */
mtsrr1 r6
RFI
#if defined(CONFIG_PPC_BOOK3S_32)
#define STACK_LR INT_FRAME_SIZE+4
/* load_up_xxx have to run with MSR_DR=0 on Book3S_32 */
#define MSR_EXT_START \
PPC_STL r20, _NIP(r1); \
mfmsr r20; \
LOAD_REG_IMMEDIATE(r3, MSR_DR|MSR_EE); \
andc r3,r20,r3; /* Disable DR,EE */ \
mtmsr r3; \
sync
#define MSR_EXT_END \
mtmsr r20; /* Enable DR,EE */ \
sync; \
PPC_LL r20, _NIP(r1)
#elif defined(CONFIG_PPC_BOOK3S_64)
#define STACK_LR _LINK
#define MSR_EXT_START
#define MSR_EXT_END
#endif
/*
* Activate current's external feature (FPU/Altivec/VSX)
*/
#define define_load_up(what) \
\
_GLOBAL(kvmppc_load_up_ ## what); \
PPC_STLU r1, -INT_FRAME_SIZE(r1); \
mflr r3; \
PPC_STL r3, STACK_LR(r1); \
MSR_EXT_START; \
\
bl FUNC(load_up_ ## what); \
\
MSR_EXT_END; \
PPC_LL r3, STACK_LR(r1); \
mtlr r3; \
addi r1, r1, INT_FRAME_SIZE; \
blr
define_load_up(fpu)
#ifdef CONFIG_ALTIVEC
define_load_up(altivec)
#endif
#ifdef CONFIG_VSX
define_load_up(vsx)
#endif
#include "book3s_segment.S"
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