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qemu/target-arm/kvm32.c
Christoffer Dall 4b7a6bf402 target-arm: kvm: Differentiate registers based on write-back levels 
Some registers like the CNTVCT register should only be written to the
kernel as part of machine initialization or on vmload operations, but
never during runtime, as this can potentially make time go backwards or
create inconsistent time observations between VCPUs.

Introduce a list of registers that should not be written back at runtime
and check this list on syncing the register state to the KVM state.

Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Message-id: 1437046488-10773-1-git-send-email-christoffer.dall@linaro.org
[PMM: tweaked a few comments, added the new argument to the stub
 write_list_to_kvmstate() in target-arm/kvm-stub.c]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2015-07-21 11:18:45 +01:00

479 lines
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/*
* ARM implementation of KVM hooks, 32 bit specific code.
*
* Copyright Christoffer Dall 2009-2010
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <linux/kvm.h>
#include "qemu-common.h"
#include "qemu/timer.h"
#include "sysemu/sysemu.h"
#include "sysemu/kvm.h"
#include "kvm_arm.h"
#include "cpu.h"
#include "internals.h"
#include "hw/arm/arm.h"
static inline void set_feature(uint64_t *features, int feature)
{
*features |= 1ULL << feature;
}
bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)
{
/* Identify the feature bits corresponding to the host CPU, and
* fill out the ARMHostCPUClass fields accordingly. To do this
* we have to create a scratch VM, create a single CPU inside it,
* and then query that CPU for the relevant ID registers.
*/
int i, ret, fdarray[3];
uint32_t midr, id_pfr0, id_isar0, mvfr1;
uint64_t features = 0;
/* Old kernels may not know about the PREFERRED_TARGET ioctl: however
* we know these will only support creating one kind of guest CPU,
* which is its preferred CPU type.
*/
static const uint32_t cpus_to_try[] = {
QEMU_KVM_ARM_TARGET_CORTEX_A15,
QEMU_KVM_ARM_TARGET_NONE
};
struct kvm_vcpu_init init;
struct kvm_one_reg idregs[] = {
{
.id = KVM_REG_ARM | KVM_REG_SIZE_U32
| ENCODE_CP_REG(15, 0, 0, 0, 0, 0, 0),
.addr = (uintptr_t)&midr,
},
{
.id = KVM_REG_ARM | KVM_REG_SIZE_U32
| ENCODE_CP_REG(15, 0, 0, 0, 1, 0, 0),
.addr = (uintptr_t)&id_pfr0,
},
{
.id = KVM_REG_ARM | KVM_REG_SIZE_U32
| ENCODE_CP_REG(15, 0, 0, 0, 2, 0, 0),
.addr = (uintptr_t)&id_isar0,
},
{
.id = KVM_REG_ARM | KVM_REG_SIZE_U32
| KVM_REG_ARM_VFP | KVM_REG_ARM_VFP_MVFR1,
.addr = (uintptr_t)&mvfr1,
},
};
if (!kvm_arm_create_scratch_host_vcpu(cpus_to_try, fdarray, &init)) {
return false;
}
ahcc->target = init.target;
/* This is not strictly blessed by the device tree binding docs yet,
* but in practice the kernel does not care about this string so
* there is no point maintaining an KVM_ARM_TARGET_* -> string table.
*/
ahcc->dtb_compatible = "arm,arm-v7";
for (i = 0; i < ARRAY_SIZE(idregs); i++) {
ret = ioctl(fdarray[2], KVM_GET_ONE_REG, &idregs[i]);
if (ret) {
break;
}
}
kvm_arm_destroy_scratch_host_vcpu(fdarray);
if (ret) {
return false;
}
/* Now we've retrieved all the register information we can
* set the feature bits based on the ID register fields.
* We can assume any KVM supporting CPU is at least a v7
* with VFPv3, LPAE and the generic timers; this in turn implies
* most of the other feature bits, but a few must be tested.
*/
set_feature(&features, ARM_FEATURE_V7);
set_feature(&features, ARM_FEATURE_VFP3);
set_feature(&features, ARM_FEATURE_LPAE);
set_feature(&features, ARM_FEATURE_GENERIC_TIMER);
switch (extract32(id_isar0, 24, 4)) {
case 1:
set_feature(&features, ARM_FEATURE_THUMB_DIV);
break;
case 2:
set_feature(&features, ARM_FEATURE_ARM_DIV);
set_feature(&features, ARM_FEATURE_THUMB_DIV);
break;
default:
break;
}
if (extract32(id_pfr0, 12, 4) == 1) {
set_feature(&features, ARM_FEATURE_THUMB2EE);
}
if (extract32(mvfr1, 20, 4) == 1) {
set_feature(&features, ARM_FEATURE_VFP_FP16);
}
if (extract32(mvfr1, 12, 4) == 1) {
set_feature(&features, ARM_FEATURE_NEON);
}
if (extract32(mvfr1, 28, 4) == 1) {
/* FMAC support implies VFPv4 */
set_feature(&features, ARM_FEATURE_VFP4);
}
ahcc->features = features;
return true;
}
bool kvm_arm_reg_syncs_via_cpreg_list(uint64_t regidx)
{
/* Return true if the regidx is a register we should synchronize
* via the cpreg_tuples array (ie is not a core reg we sync by
* hand in kvm_arch_get/put_registers())
*/
switch (regidx & KVM_REG_ARM_COPROC_MASK) {
case KVM_REG_ARM_CORE:
case KVM_REG_ARM_VFP:
return false;
default:
return true;
}
}
typedef struct CPRegStateLevel {
uint64_t regidx;
int level;
} CPRegStateLevel;
/* All coprocessor registers not listed in the following table are assumed to
* be of the level KVM_PUT_RUNTIME_STATE. If a register should be written less
* often, you must add it to this table with a state of either
* KVM_PUT_RESET_STATE or KVM_PUT_FULL_STATE.
*/
static const CPRegStateLevel non_runtime_cpregs[] = {
{ KVM_REG_ARM_TIMER_CNT, KVM_PUT_FULL_STATE },
};
int kvm_arm_cpreg_level(uint64_t regidx)
{
int i;
for (i = 0; i < ARRAY_SIZE(non_runtime_cpregs); i++) {
const CPRegStateLevel *l = &non_runtime_cpregs[i];
if (l->regidx == regidx) {
return l->level;
}
}
return KVM_PUT_RUNTIME_STATE;
}
#define ARM_MPIDR_HWID_BITMASK 0xFFFFFF
#define ARM_CPU_ID_MPIDR 0, 0, 0, 5
int kvm_arch_init_vcpu(CPUState *cs)
{
int ret;
uint64_t v;
uint32_t mpidr;
struct kvm_one_reg r;
ARMCPU *cpu = ARM_CPU(cs);
if (cpu->kvm_target == QEMU_KVM_ARM_TARGET_NONE) {
fprintf(stderr, "KVM is not supported for this guest CPU type\n");
return -EINVAL;
}
/* Determine init features for this CPU */
memset(cpu->kvm_init_features, 0, sizeof(cpu->kvm_init_features));
if (cpu->start_powered_off) {
cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_POWER_OFF;
}
if (kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PSCI_0_2)) {
cpu->psci_version = 2;
cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PSCI_0_2;
}
/* Do KVM_ARM_VCPU_INIT ioctl */
ret = kvm_arm_vcpu_init(cs);
if (ret) {
return ret;
}
/* Query the kernel to make sure it supports 32 VFP
* registers: QEMU's "cortex-a15" CPU is always a
* VFP-D32 core. The simplest way to do this is just
* to attempt to read register d31.
*/
r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP | 31;
r.addr = (uintptr_t)(&v);
ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
if (ret == -ENOENT) {
return -EINVAL;
}
/*
* When KVM is in use, PSCI is emulated in-kernel and not by qemu.
* Currently KVM has its own idea about MPIDR assignment, so we
* override our defaults with what we get from KVM.
*/
ret = kvm_get_one_reg(cs, ARM_CP15_REG32(ARM_CPU_ID_MPIDR), &mpidr);
if (ret) {
return ret;
}
cpu->mp_affinity = mpidr & ARM_MPIDR_HWID_BITMASK;
return kvm_arm_init_cpreg_list(cpu);
}
typedef struct Reg {
uint64_t id;
int offset;
} Reg;
#define COREREG(KERNELNAME, QEMUFIELD) \
{ \
KVM_REG_ARM | KVM_REG_SIZE_U32 | \
KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(KERNELNAME), \
offsetof(CPUARMState, QEMUFIELD) \
}
#define VFPSYSREG(R) \
{ \
KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP | \
KVM_REG_ARM_VFP_##R, \
offsetof(CPUARMState, vfp.xregs[ARM_VFP_##R]) \
}
/* Like COREREG, but handle fields which are in a uint64_t in CPUARMState. */
#define COREREG64(KERNELNAME, QEMUFIELD) \
{ \
KVM_REG_ARM | KVM_REG_SIZE_U32 | \
KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(KERNELNAME), \
offsetoflow32(CPUARMState, QEMUFIELD) \
}
static const Reg regs[] = {
/* R0_usr .. R14_usr */
COREREG(usr_regs.uregs[0], regs[0]),
COREREG(usr_regs.uregs[1], regs[1]),
COREREG(usr_regs.uregs[2], regs[2]),
COREREG(usr_regs.uregs[3], regs[3]),
COREREG(usr_regs.uregs[4], regs[4]),
COREREG(usr_regs.uregs[5], regs[5]),
COREREG(usr_regs.uregs[6], regs[6]),
COREREG(usr_regs.uregs[7], regs[7]),
COREREG(usr_regs.uregs[8], usr_regs[0]),
COREREG(usr_regs.uregs[9], usr_regs[1]),
COREREG(usr_regs.uregs[10], usr_regs[2]),
COREREG(usr_regs.uregs[11], usr_regs[3]),
COREREG(usr_regs.uregs[12], usr_regs[4]),
COREREG(usr_regs.uregs[13], banked_r13[0]),
COREREG(usr_regs.uregs[14], banked_r14[0]),
/* R13, R14, SPSR for SVC, ABT, UND, IRQ banks */
COREREG(svc_regs[0], banked_r13[1]),
COREREG(svc_regs[1], banked_r14[1]),
COREREG64(svc_regs[2], banked_spsr[1]),
COREREG(abt_regs[0], banked_r13[2]),
COREREG(abt_regs[1], banked_r14[2]),
COREREG64(abt_regs[2], banked_spsr[2]),
COREREG(und_regs[0], banked_r13[3]),
COREREG(und_regs[1], banked_r14[3]),
COREREG64(und_regs[2], banked_spsr[3]),
COREREG(irq_regs[0], banked_r13[4]),
COREREG(irq_regs[1], banked_r14[4]),
COREREG64(irq_regs[2], banked_spsr[4]),
/* R8_fiq .. R14_fiq and SPSR_fiq */
COREREG(fiq_regs[0], fiq_regs[0]),
COREREG(fiq_regs[1], fiq_regs[1]),
COREREG(fiq_regs[2], fiq_regs[2]),
COREREG(fiq_regs[3], fiq_regs[3]),
COREREG(fiq_regs[4], fiq_regs[4]),
COREREG(fiq_regs[5], banked_r13[5]),
COREREG(fiq_regs[6], banked_r14[5]),
COREREG64(fiq_regs[7], banked_spsr[5]),
/* R15 */
COREREG(usr_regs.uregs[15], regs[15]),
/* VFP system registers */
VFPSYSREG(FPSID),
VFPSYSREG(MVFR1),
VFPSYSREG(MVFR0),
VFPSYSREG(FPEXC),
VFPSYSREG(FPINST),
VFPSYSREG(FPINST2),
};
int kvm_arch_put_registers(CPUState *cs, int level)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
struct kvm_one_reg r;
int mode, bn;
int ret, i;
uint32_t cpsr, fpscr;
/* Make sure the banked regs are properly set */
mode = env->uncached_cpsr & CPSR_M;
bn = bank_number(mode);
if (mode == ARM_CPU_MODE_FIQ) {
memcpy(env->fiq_regs, env->regs + 8, 5 * sizeof(uint32_t));
} else {
memcpy(env->usr_regs, env->regs + 8, 5 * sizeof(uint32_t));
}
env->banked_r13[bn] = env->regs[13];
env->banked_r14[bn] = env->regs[14];
env->banked_spsr[bn] = env->spsr;
/* Now we can safely copy stuff down to the kernel */
for (i = 0; i < ARRAY_SIZE(regs); i++) {
r.id = regs[i].id;
r.addr = (uintptr_t)(env) + regs[i].offset;
ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
if (ret) {
return ret;
}
}
/* Special cases which aren't a single CPUARMState field */
cpsr = cpsr_read(env);
r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 |
KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(usr_regs.ARM_cpsr);
r.addr = (uintptr_t)(&cpsr);
ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
if (ret) {
return ret;
}
/* VFP registers */
r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP;
for (i = 0; i < 32; i++) {
r.addr = (uintptr_t)(&env->vfp.regs[i]);
ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
if (ret) {
return ret;
}
r.id++;
}
r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP |
KVM_REG_ARM_VFP_FPSCR;
fpscr = vfp_get_fpscr(env);
r.addr = (uintptr_t)&fpscr;
ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
if (ret) {
return ret;
}
/* Note that we do not call write_cpustate_to_list()
* here, so we are only writing the tuple list back to
* KVM. This is safe because nothing can change the
* CPUARMState cp15 fields (in particular gdb accesses cannot)
* and so there are no changes to sync. In fact syncing would
* be wrong at this point: for a constant register where TCG and
* KVM disagree about its value, the preceding write_list_to_cpustate()
* would not have had any effect on the CPUARMState value (since the
* register is read-only), and a write_cpustate_to_list() here would
* then try to write the TCG value back into KVM -- this would either
* fail or incorrectly change the value the guest sees.
*
* If we ever want to allow the user to modify cp15 registers via
* the gdb stub, we would need to be more clever here (for instance
* tracking the set of registers kvm_arch_get_registers() successfully
* managed to update the CPUARMState with, and only allowing those
* to be written back up into the kernel).
*/
if (!write_list_to_kvmstate(cpu, level)) {
return EINVAL;
}
kvm_arm_sync_mpstate_to_kvm(cpu);
return ret;
}
int kvm_arch_get_registers(CPUState *cs)
{
ARMCPU *cpu = ARM_CPU(cs);
CPUARMState *env = &cpu->env;
struct kvm_one_reg r;
int mode, bn;
int ret, i;
uint32_t cpsr, fpscr;
for (i = 0; i < ARRAY_SIZE(regs); i++) {
r.id = regs[i].id;
r.addr = (uintptr_t)(env) + regs[i].offset;
ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
if (ret) {
return ret;
}
}
/* Special cases which aren't a single CPUARMState field */
r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 |
KVM_REG_ARM_CORE | KVM_REG_ARM_CORE_REG(usr_regs.ARM_cpsr);
r.addr = (uintptr_t)(&cpsr);
ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
if (ret) {
return ret;
}
cpsr_write(env, cpsr, 0xffffffff);
/* Make sure the current mode regs are properly set */
mode = env->uncached_cpsr & CPSR_M;
bn = bank_number(mode);
if (mode == ARM_CPU_MODE_FIQ) {
memcpy(env->regs + 8, env->fiq_regs, 5 * sizeof(uint32_t));
} else {
memcpy(env->regs + 8, env->usr_regs, 5 * sizeof(uint32_t));
}
env->regs[13] = env->banked_r13[bn];
env->regs[14] = env->banked_r14[bn];
env->spsr = env->banked_spsr[bn];
/* VFP registers */
r.id = KVM_REG_ARM | KVM_REG_SIZE_U64 | KVM_REG_ARM_VFP;
for (i = 0; i < 32; i++) {
r.addr = (uintptr_t)(&env->vfp.regs[i]);
ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
if (ret) {
return ret;
}
r.id++;
}
r.id = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_VFP |
KVM_REG_ARM_VFP_FPSCR;
r.addr = (uintptr_t)&fpscr;
ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
if (ret) {
return ret;
}
vfp_set_fpscr(env, fpscr);
if (!write_kvmstate_to_list(cpu)) {
return EINVAL;
}
/* Note that it's OK to have registers which aren't in CPUState,
* so we can ignore a failure return here.
*/
write_list_to_cpustate(cpu);
kvm_arm_sync_mpstate_to_qemu(cpu);
return 0;
}
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