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KVM: PPC: Book3E: Increase FPU laziness

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Increase FPU laziness by loading the guest state into the unit before entering
the guest instead of doing it on each vcpu schedule. Without this improvement
an interrupt may claim floating point corrupting guest state.

Signed-off-by: Mihai Caraman <mihai.caraman@freescale.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Mihai Caraman 2014-08-20 16:36:22 +03:00 committed by Alexander Graf
parent bc8a4e5c25
commit 3efc7da61f
3 changed files with 36 additions and 43 deletions
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43
arch/powerpc/kvm/booke.c
View File

@ -124,6 +124,40 @@ static void kvmppc_vcpu_sync_spe(struct kvm_vcpu *vcpu)
}
#endif
/*
* Load up guest vcpu FP state if it's needed.
* It also set the MSR_FP in thread so that host know
* we're holding FPU, and then host can help to save
* guest vcpu FP state if other threads require to use FPU.
* This simulates an FP unavailable fault.
*
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_load_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (!(current->thread.regs->msr & MSR_FP)) {
enable_kernel_fp();
load_fp_state(&vcpu->arch.fp);
current->thread.fp_save_area = &vcpu->arch.fp;
current->thread.regs->msr |= MSR_FP;
}
#endif
}
/*
* Save guest vcpu FP state into thread.
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_save_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (current->thread.regs->msr & MSR_FP)
giveup_fpu(current);
current->thread.fp_save_area = NULL;
#endif
}
static void kvmppc_vcpu_sync_fpu(struct kvm_vcpu *vcpu)
{
#if defined(CONFIG_PPC_FPU) && !defined(CONFIG_KVM_BOOKE_HV)
@ -658,12 +692,8 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
/*
* Since we can't trap on MSR_FP in GS-mode, we consider the guest
* as always using the FPU. Kernel usage of FP (via
* enable_kernel_fp()) in this thread must not occur while
* vcpu->fpu_active is set.
* as always using the FPU.
*/
vcpu->fpu_active = 1;
kvmppc_load_guest_fp(vcpu);
#endif
@ -687,8 +717,6 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
#ifdef CONFIG_PPC_FPU
kvmppc_save_guest_fp(vcpu);
vcpu->fpu_active = 0;
#endif
out:
@ -1194,6 +1222,7 @@ out:
else {
/* interrupts now hard-disabled */
kvmppc_fix_ee_before_entry();
kvmppc_load_guest_fp(vcpu);
}
}

34
arch/powerpc/kvm/booke.h
View File

@ -116,40 +116,6 @@ extern int kvmppc_core_emulate_mtspr_e500(struct kvm_vcpu *vcpu, int sprn,
extern int kvmppc_core_emulate_mfspr_e500(struct kvm_vcpu *vcpu, int sprn,
ulong *spr_val);
/*
* Load up guest vcpu FP state if it's needed.
* It also set the MSR_FP in thread so that host know
* we're holding FPU, and then host can help to save
* guest vcpu FP state if other threads require to use FPU.
* This simulates an FP unavailable fault.
*
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_load_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (vcpu->fpu_active && !(current->thread.regs->msr & MSR_FP)) {
enable_kernel_fp();
load_fp_state(&vcpu->arch.fp);
current->thread.fp_save_area = &vcpu->arch.fp;
current->thread.regs->msr |= MSR_FP;
}
#endif
}
/*
* Save guest vcpu FP state into thread.
* It requires to be called with preemption disabled.
*/
static inline void kvmppc_save_guest_fp(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_PPC_FPU
if (vcpu->fpu_active && (current->thread.regs->msr & MSR_FP))
giveup_fpu(current);
current->thread.fp_save_area = NULL;
#endif
}
static inline void kvmppc_clear_dbsr(void)
{
mtspr(SPRN_DBSR, mfspr(SPRN_DBSR));

2
arch/powerpc/kvm/e500mc.c
View File

@ -145,8 +145,6 @@ static void kvmppc_core_vcpu_load_e500mc(struct kvm_vcpu *vcpu, int cpu)
kvmppc_e500_tlbil_all(vcpu_e500);
__get_cpu_var(last_vcpu_of_lpid)[vcpu->kvm->arch.lpid] = vcpu;
}
kvmppc_load_guest_fp(vcpu);
}
static void kvmppc_core_vcpu_put_e500mc(struct kvm_vcpu *vcpu)