linux/arch/powerpc/kvm/44x_emulate.c
Alexander Graf 54771e6217 KVM: PPC: Emulator: clean up SPR reads and writes
When reading and writing SPRs, every SPR emulation piece had to read
or write the respective GPR the value was read from or stored in itself.

This approach is pretty prone to failure. What if we accidentally
implement mfspr emulation where we just do "break" and nothing else?
Suddenly we would get a random value in the return register - which is
always a bad idea.

So let's consolidate the generic code paths and only give the core
specific SPR handling code readily made variables to read/write from/to.

Functionally, this patch doesn't change anything, but it increases the
readability of the code and makes is less prone to bugs.

Signed-off-by: Alexander Graf <agraf@suse.de>
2012-05-06 16:19:13 +02:00

171 lines
4.1 KiB
C

/*
* 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. 2008
*
* Authors: Hollis Blanchard <hollisb@us.ibm.com>
*/
#include <asm/kvm_ppc.h>
#include <asm/dcr.h>
#include <asm/dcr-regs.h>
#include <asm/disassemble.h>
#include <asm/kvm_44x.h>
#include "timing.h"
#include "booke.h"
#include "44x_tlb.h"
#define XOP_MFDCR 323
#define XOP_MTDCR 451
#define XOP_TLBSX 914
#define XOP_ICCCI 966
#define XOP_TLBWE 978
int kvmppc_core_emulate_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int inst, int *advance)
{
int emulated = EMULATE_DONE;
int dcrn = get_dcrn(inst);
int ra = get_ra(inst);
int rb = get_rb(inst);
int rc = get_rc(inst);
int rs = get_rs(inst);
int rt = get_rt(inst);
int ws = get_ws(inst);
switch (get_op(inst)) {
case 31:
switch (get_xop(inst)) {
case XOP_MFDCR:
/* The guest may access CPR0 registers to determine the timebase
* frequency, and it must know the real host frequency because it
* can directly access the timebase registers.
*
* It would be possible to emulate those accesses in userspace,
* but userspace can really only figure out the end frequency.
* We could decompose that into the factors that compute it, but
* that's tricky math, and it's easier to just report the real
* CPR0 values.
*/
switch (dcrn) {
case DCRN_CPR0_CONFIG_ADDR:
kvmppc_set_gpr(vcpu, rt, vcpu->arch.cpr0_cfgaddr);
break;
case DCRN_CPR0_CONFIG_DATA:
local_irq_disable();
mtdcr(DCRN_CPR0_CONFIG_ADDR,
vcpu->arch.cpr0_cfgaddr);
kvmppc_set_gpr(vcpu, rt,
mfdcr(DCRN_CPR0_CONFIG_DATA));
local_irq_enable();
break;
default:
run->dcr.dcrn = dcrn;
run->dcr.data = 0;
run->dcr.is_write = 0;
vcpu->arch.io_gpr = rt;
vcpu->arch.dcr_needed = 1;
kvmppc_account_exit(vcpu, DCR_EXITS);
emulated = EMULATE_DO_DCR;
}
break;
case XOP_MTDCR:
/* emulate some access in kernel */
switch (dcrn) {
case DCRN_CPR0_CONFIG_ADDR:
vcpu->arch.cpr0_cfgaddr = kvmppc_get_gpr(vcpu, rs);
break;
default:
run->dcr.dcrn = dcrn;
run->dcr.data = kvmppc_get_gpr(vcpu, rs);
run->dcr.is_write = 1;
vcpu->arch.dcr_needed = 1;
kvmppc_account_exit(vcpu, DCR_EXITS);
emulated = EMULATE_DO_DCR;
}
break;
case XOP_TLBWE:
emulated = kvmppc_44x_emul_tlbwe(vcpu, ra, rs, ws);
break;
case XOP_TLBSX:
emulated = kvmppc_44x_emul_tlbsx(vcpu, rt, ra, rb, rc);
break;
case XOP_ICCCI:
break;
default:
emulated = EMULATE_FAIL;
}
break;
default:
emulated = EMULATE_FAIL;
}
if (emulated == EMULATE_FAIL)
emulated = kvmppc_booke_emulate_op(run, vcpu, inst, advance);
return emulated;
}
int kvmppc_core_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, ulong spr_val)
{
int emulated = EMULATE_DONE;
switch (sprn) {
case SPRN_PID:
kvmppc_set_pid(vcpu, spr_val); break;
case SPRN_MMUCR:
vcpu->arch.mmucr = spr_val; break;
case SPRN_CCR0:
vcpu->arch.ccr0 = spr_val; break;
case SPRN_CCR1:
vcpu->arch.ccr1 = spr_val; break;
default:
emulated = kvmppc_booke_emulate_mtspr(vcpu, sprn, spr_val);
}
return emulated;
}
int kvmppc_core_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, ulong *spr_val)
{
int emulated = EMULATE_DONE;
switch (sprn) {
case SPRN_PID:
*spr_val = vcpu->arch.pid; break;
case SPRN_MMUCR:
*spr_val = vcpu->arch.mmucr; break;
case SPRN_CCR0:
*spr_val = vcpu->arch.ccr0; break;
case SPRN_CCR1:
*spr_val = vcpu->arch.ccr1; break;
default:
emulated = kvmppc_booke_emulate_mfspr(vcpu, sprn, spr_val);
}
return emulated;
}