Increase FPU laziness by calling kvmppc_load_guest_fp() just before
returning to guest instead of each sched in. Without this improvement
an interrupt may also claim floting point corrupting guest state.
Signed-off-by: Mihai Caraman <mihai.caraman@xxxxxxxxxxxxx>
---
v3:
- no changes
v2:
- remove fpu_active
- add descriptive comments
arch/powerpc/kvm/booke.c | 43 ++++++++++++++++++++++++++++++++++++-------
arch/powerpc/kvm/booke.h | 34 ----------------------------------
arch/powerpc/kvm/e500mc.c | 2 --
3 files changed, 36 insertions(+), 43 deletions(-)
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index b4c89fa..0c6f616 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -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)
@@ -654,12 +688,8 @@ 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
@@ -683,8 +713,6 @@ 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:
@@ -1188,6 +1216,7 @@ out:
else {
/* interrupts now hard-disabled */
kvmppc_fix_ee_before_entry();
+ kvmppc_load_guest_fp(vcpu);
}
}
diff --git a/arch/powerpc/kvm/booke.h b/arch/powerpc/kvm/booke.h
index f753543..e73d513 100644
--- a/arch/powerpc/kvm/booke.h
+++ b/arch/powerpc/kvm/booke.h
@@ -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));
diff --git a/arch/powerpc/kvm/e500mc.c b/arch/powerpc/kvm/e500mc.c
index 164bad2..67c06eb 100644
--- a/arch/powerpc/kvm/e500mc.c
+++ b/arch/powerpc/kvm/e500mc.c
@@ -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)
--
1.7.11.7
--
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