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KVM: PPC: Add support for FPU/Altivec/VSX
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When our guest starts using either the FPU, Altivec or VSX we need to make
sure Linux knows about it and sneak into its process switching code
accordingly.

This patch makes accesses to the above parts of the system work inside the
VM.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
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Alexander Graf authored and Marcelo Tosatti committed Mar 1, 2010
1 parent d5e5281 commit 180a34d
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Showing 2 changed files with 201 additions and 6 deletions.
14 changes: 13 additions & 1 deletion arch/powerpc/include/asm/kvm_host.h
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Original file line number Diff line number Diff line change
Expand Up @@ -172,9 +172,20 @@ struct kvm_vcpu_arch {
struct kvmppc_mmu mmu;
#endif

u64 fpr[32];
ulong gpr[32];

u64 fpr[32];
u32 fpscr;

#ifdef CONFIG_ALTIVEC
vector128 vr[32];
vector128 vscr;
#endif

#ifdef CONFIG_VSX
u64 vsr[32];
#endif

ulong pc;
ulong ctr;
ulong lr;
Expand All @@ -188,6 +199,7 @@ struct kvm_vcpu_arch {
#ifdef CONFIG_PPC64
ulong shadow_msr;
ulong hflags;
ulong guest_owned_ext;
#endif
u32 mmucr;
ulong sprg0;
Expand Down
193 changes: 188 additions & 5 deletions arch/powerpc/kvm/book3s.c
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Original file line number Diff line number Diff line change
Expand Up @@ -33,6 +33,9 @@

/* #define EXIT_DEBUG */
/* #define EXIT_DEBUG_SIMPLE */
/* #define DEBUG_EXT */

static void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr);

struct kvm_stats_debugfs_item debugfs_entries[] = {
{ "exits", VCPU_STAT(sum_exits) },
Expand Down Expand Up @@ -77,6 +80,10 @@ void kvmppc_core_vcpu_put(struct kvm_vcpu *vcpu)
memcpy(&to_book3s(vcpu)->shadow_vcpu, &get_paca()->shadow_vcpu,
sizeof(get_paca()->shadow_vcpu));
to_book3s(vcpu)->slb_shadow_max = get_paca()->kvm_slb_max;

kvmppc_giveup_ext(vcpu, MSR_FP);
kvmppc_giveup_ext(vcpu, MSR_VEC);
kvmppc_giveup_ext(vcpu, MSR_VSX);
}

#if defined(EXIT_DEBUG)
Expand All @@ -97,9 +104,9 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u64 msr)
msr &= to_book3s(vcpu)->msr_mask;
vcpu->arch.msr = msr;
vcpu->arch.shadow_msr = msr | MSR_USER32;
vcpu->arch.shadow_msr &= ( MSR_VEC | MSR_VSX | MSR_FP | MSR_FE0 |
MSR_USER64 | MSR_SE | MSR_BE | MSR_DE |
MSR_FE1);
vcpu->arch.shadow_msr &= (MSR_FE0 | MSR_USER64 | MSR_SE | MSR_BE |
MSR_DE | MSR_FE1);
vcpu->arch.shadow_msr |= (msr & vcpu->arch.guest_owned_ext);

if (msr & (MSR_WE|MSR_POW)) {
if (!vcpu->arch.pending_exceptions) {
Expand Down Expand Up @@ -551,6 +558,117 @@ int kvmppc_handle_pagefault(struct kvm_run *run, struct kvm_vcpu *vcpu,
return r;
}

static inline int get_fpr_index(int i)
{
#ifdef CONFIG_VSX
i *= 2;
#endif
return i;
}

/* Give up external provider (FPU, Altivec, VSX) */
static void kvmppc_giveup_ext(struct kvm_vcpu *vcpu, ulong msr)
{
struct thread_struct *t = &current->thread;
u64 *vcpu_fpr = vcpu->arch.fpr;
u64 *vcpu_vsx = vcpu->arch.vsr;
u64 *thread_fpr = (u64*)t->fpr;
int i;

if (!(vcpu->arch.guest_owned_ext & msr))
return;

#ifdef DEBUG_EXT
printk(KERN_INFO "Giving up ext 0x%lx\n", msr);
#endif

switch (msr) {
case MSR_FP:
giveup_fpu(current);
for (i = 0; i < ARRAY_SIZE(vcpu->arch.fpr); i++)
vcpu_fpr[i] = thread_fpr[get_fpr_index(i)];

vcpu->arch.fpscr = t->fpscr.val;
break;
case MSR_VEC:
#ifdef CONFIG_ALTIVEC
giveup_altivec(current);
memcpy(vcpu->arch.vr, t->vr, sizeof(vcpu->arch.vr));
vcpu->arch.vscr = t->vscr;
#endif
break;
case MSR_VSX:
#ifdef CONFIG_VSX
__giveup_vsx(current);
for (i = 0; i < ARRAY_SIZE(vcpu->arch.vsr); i++)
vcpu_vsx[i] = thread_fpr[get_fpr_index(i) + 1];
#endif
break;
default:
BUG();
}

vcpu->arch.guest_owned_ext &= ~msr;
current->thread.regs->msr &= ~msr;
kvmppc_set_msr(vcpu, vcpu->arch.msr);
}

/* Handle external providers (FPU, Altivec, VSX) */
static int kvmppc_handle_ext(struct kvm_vcpu *vcpu, unsigned int exit_nr,
ulong msr)
{
struct thread_struct *t = &current->thread;
u64 *vcpu_fpr = vcpu->arch.fpr;
u64 *vcpu_vsx = vcpu->arch.vsr;
u64 *thread_fpr = (u64*)t->fpr;
int i;

if (!(vcpu->arch.msr & msr)) {
kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
return RESUME_GUEST;
}

#ifdef DEBUG_EXT
printk(KERN_INFO "Loading up ext 0x%lx\n", msr);
#endif

current->thread.regs->msr |= msr;

switch (msr) {
case MSR_FP:
for (i = 0; i < ARRAY_SIZE(vcpu->arch.fpr); i++)
thread_fpr[get_fpr_index(i)] = vcpu_fpr[i];

t->fpscr.val = vcpu->arch.fpscr;
t->fpexc_mode = 0;
kvmppc_load_up_fpu();
break;
case MSR_VEC:
#ifdef CONFIG_ALTIVEC
memcpy(t->vr, vcpu->arch.vr, sizeof(vcpu->arch.vr));
t->vscr = vcpu->arch.vscr;
t->vrsave = -1;
kvmppc_load_up_altivec();
#endif
break;
case MSR_VSX:
#ifdef CONFIG_VSX
for (i = 0; i < ARRAY_SIZE(vcpu->arch.vsr); i++)
thread_fpr[get_fpr_index(i) + 1] = vcpu_vsx[i];
kvmppc_load_up_vsx();
#endif
break;
default:
BUG();
}

vcpu->arch.guest_owned_ext |= msr;

kvmppc_set_msr(vcpu, vcpu->arch.msr);

return RESUME_GUEST;
}

int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
unsigned int exit_nr)
{
Expand Down Expand Up @@ -674,11 +792,17 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
r = RESUME_GUEST;
break;
case BOOK3S_INTERRUPT_MACHINE_CHECK:
case BOOK3S_INTERRUPT_FP_UNAVAIL:
case BOOK3S_INTERRUPT_TRACE:
r = kvmppc_handle_ext(vcpu, exit_nr, MSR_FP);
break;
case BOOK3S_INTERRUPT_ALTIVEC:
r = kvmppc_handle_ext(vcpu, exit_nr, MSR_VEC);
break;
case BOOK3S_INTERRUPT_VSX:
r = kvmppc_handle_ext(vcpu, exit_nr, MSR_VSX);
break;
case BOOK3S_INTERRUPT_MACHINE_CHECK:
case BOOK3S_INTERRUPT_TRACE:
kvmppc_book3s_queue_irqprio(vcpu, exit_nr);
r = RESUME_GUEST;
break;
Expand Down Expand Up @@ -959,20 +1083,79 @@ extern int __kvmppc_vcpu_entry(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu);
int __kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
{
int ret;
struct thread_struct ext_bkp;
bool save_vec = current->thread.used_vr;
bool save_vsx = current->thread.used_vsr;
ulong ext_msr;

/* No need to go into the guest when all we do is going out */
if (signal_pending(current)) {
kvm_run->exit_reason = KVM_EXIT_INTR;
return -EINTR;
}

/* Save FPU state in stack */
if (current->thread.regs->msr & MSR_FP)
giveup_fpu(current);
memcpy(ext_bkp.fpr, current->thread.fpr, sizeof(current->thread.fpr));
ext_bkp.fpscr = current->thread.fpscr;
ext_bkp.fpexc_mode = current->thread.fpexc_mode;

#ifdef CONFIG_ALTIVEC
/* Save Altivec state in stack */
if (save_vec) {
if (current->thread.regs->msr & MSR_VEC)
giveup_altivec(current);
memcpy(ext_bkp.vr, current->thread.vr, sizeof(ext_bkp.vr));
ext_bkp.vscr = current->thread.vscr;
ext_bkp.vrsave = current->thread.vrsave;
}
ext_bkp.used_vr = current->thread.used_vr;
#endif

#ifdef CONFIG_VSX
/* Save VSX state in stack */
if (save_vsx && (current->thread.regs->msr & MSR_VSX))
__giveup_vsx(current);
ext_bkp.used_vsr = current->thread.used_vsr;
#endif

/* Remember the MSR with disabled extensions */
ext_msr = current->thread.regs->msr;

/* XXX we get called with irq disabled - change that! */
local_irq_enable();

ret = __kvmppc_vcpu_entry(kvm_run, vcpu);

local_irq_disable();

current->thread.regs->msr = ext_msr;

/* Make sure we save the guest FPU/Altivec/VSX state */
kvmppc_giveup_ext(vcpu, MSR_FP);
kvmppc_giveup_ext(vcpu, MSR_VEC);
kvmppc_giveup_ext(vcpu, MSR_VSX);

/* Restore FPU state from stack */
memcpy(current->thread.fpr, ext_bkp.fpr, sizeof(ext_bkp.fpr));
current->thread.fpscr = ext_bkp.fpscr;
current->thread.fpexc_mode = ext_bkp.fpexc_mode;

#ifdef CONFIG_ALTIVEC
/* Restore Altivec state from stack */
if (save_vec && current->thread.used_vr) {
memcpy(current->thread.vr, ext_bkp.vr, sizeof(ext_bkp.vr));
current->thread.vscr = ext_bkp.vscr;
current->thread.vrsave= ext_bkp.vrsave;
}
current->thread.used_vr = ext_bkp.used_vr;
#endif

#ifdef CONFIG_VSX
current->thread.used_vsr = ext_bkp.used_vsr;
#endif

return ret;
}

Expand Down

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