Rearrange the MSR saving on entry so it does not follow the mtmsrd to
disable interrupts, avoiding a possible RAW scoreboard stall.
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
arch/powerpc/include/asm/kvm_book3s_64.h | 2 +
arch/powerpc/kvm/book3s_hv.c | 18 ++-----
arch/powerpc/kvm/book3s_hv_p9_entry.c | 66 +++++++++++++++---------
3 files changed, 47 insertions(+), 39 deletions(-)
diff --git a/arch/powerpc/include/asm/kvm_book3s_64.h b/arch/powerpc/include/asm/kvm_book3s_64.h
index f721bb1a5eab..ee25e93febe6 100644
--- a/arch/powerpc/include/asm/kvm_book3s_64.h
+++ b/arch/powerpc/include/asm/kvm_book3s_64.h
@@ -154,6 +154,8 @@ static inline bool kvmhv_vcpu_is_radix(struct kvm_vcpu *vcpu)
return radix;
}
+unsigned long kvmppc_msr_hard_disable_set_facilities(struct kvm_vcpu *vcpu, unsigned long msr);
+
int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb);
#define KVM_DEFAULT_HPT_ORDER 24 /* 16MB HPT by default */
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 7337c0ca94c6..979223018c8e 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -3881,6 +3881,8 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns
s64 dec;
int trap;
+ msr = mfmsr();
+
save_p9_host_os_sprs(&host_os_sprs);
/*
@@ -3891,24 +3893,10 @@ static int kvmhv_vcpu_entry_p9_nested(struct kvm_vcpu *vcpu, u64 time_limit, uns
*/
host_psscr = mfspr(SPRN_PSSCR_PR);
- hard_irq_disable();
+ kvmppc_msr_hard_disable_set_facilities(vcpu, msr);
if (lazy_irq_pending())
return 0;
- /* MSR bits may have been cleared by context switch */
- msr = 0;
- if (IS_ENABLED(CONFIG_PPC_FPU))
- msr |= MSR_FP;
- if (cpu_has_feature(CPU_FTR_ALTIVEC))
- msr |= MSR_VEC;
- if (cpu_has_feature(CPU_FTR_VSX))
- msr |= MSR_VSX;
- if ((cpu_has_feature(CPU_FTR_TM) ||
- cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) &&
- (vcpu->arch.hfscr & HFSCR_TM))
- msr |= MSR_TM;
- msr = msr_check_and_set(msr);
-
if (unlikely(load_vcpu_state(vcpu, &host_os_sprs)))
msr = mfmsr(); /* TM restore can update msr */
diff --git a/arch/powerpc/kvm/book3s_hv_p9_entry.c b/arch/powerpc/kvm/book3s_hv_p9_entry.c
index 94b15294a388..fa6ac153c0f9 100644
--- a/arch/powerpc/kvm/book3s_hv_p9_entry.c
+++ b/arch/powerpc/kvm/book3s_hv_p9_entry.c
@@ -628,6 +628,44 @@ static void save_clear_guest_mmu(struct kvm *kvm, struct kvm_vcpu *vcpu)
}
}
+unsigned long kvmppc_msr_hard_disable_set_facilities(struct kvm_vcpu *vcpu, unsigned long msr)
+{
+ unsigned long msr_needed = 0;
+
+ msr &= ~MSR_EE;
+
+ /* MSR bits may have been cleared by context switch so must recheck */
+ if (IS_ENABLED(CONFIG_PPC_FPU))
+ msr_needed |= MSR_FP;
+ if (cpu_has_feature(CPU_FTR_ALTIVEC))
+ msr_needed |= MSR_VEC;
+ if (cpu_has_feature(CPU_FTR_VSX))
+ msr_needed |= MSR_VSX;
+ if ((cpu_has_feature(CPU_FTR_TM) ||
+ cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) &&
+ (vcpu->arch.hfscr & HFSCR_TM))
+ msr_needed |= MSR_TM;
+
+ /*
+ * This could be combined with MSR[RI] clearing, but that expands
+ * the unrecoverable window. It would be better to cover unrecoverable
+ * with KVM bad interrupt handling rather than use MSR[RI] at all.
+ *
+ * Much more difficult and less worthwhile to combine with IR/DR
+ * disable.
+ */
+ if ((msr & msr_needed) != msr_needed) {
+ msr |= msr_needed;
+ __mtmsrd(msr, 0);
+ } else {
+ __hard_irq_disable();
+ }
+ local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
+
+ return msr;
+}
+EXPORT_SYMBOL_GPL(kvmppc_msr_hard_disable_set_facilities);
+
int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpcr, u64 *tb)
{
struct p9_host_os_sprs host_os_sprs;
@@ -661,6 +699,9 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc
vcpu->arch.ceded = 0;
+ /* Save MSR for restore, with EE clear. */
+ msr = mfmsr() & ~MSR_EE;
+
host_hfscr = mfspr(SPRN_HFSCR);
host_ciabr = mfspr(SPRN_CIABR);
host_psscr = mfspr(SPRN_PSSCR_PR);
@@ -682,35 +723,12 @@ int kvmhv_vcpu_entry_p9(struct kvm_vcpu *vcpu, u64 time_limit, unsigned long lpc
save_p9_host_os_sprs(&host_os_sprs);
- /*
- * This could be combined with MSR[RI] clearing, but that expands
- * the unrecoverable window. It would be better to cover unrecoverable
- * with KVM bad interrupt handling rather than use MSR[RI] at all.
- *
- * Much more difficult and less worthwhile to combine with IR/DR
- * disable.
- */
- hard_irq_disable();
+ msr = kvmppc_msr_hard_disable_set_facilities(vcpu, msr);
if (lazy_irq_pending()) {
trap = 0;
goto out;
}
- /* MSR bits may have been cleared by context switch */
- msr = 0;
- if (IS_ENABLED(CONFIG_PPC_FPU))
- msr |= MSR_FP;
- if (cpu_has_feature(CPU_FTR_ALTIVEC))
- msr |= MSR_VEC;
- if (cpu_has_feature(CPU_FTR_VSX))
- msr |= MSR_VSX;
- if ((cpu_has_feature(CPU_FTR_TM) ||
- cpu_has_feature(CPU_FTR_P9_TM_HV_ASSIST)) &&
- (vcpu->arch.hfscr & HFSCR_TM))
- msr |= MSR_TM;
- msr = msr_check_and_set(msr);
- /* Save MSR for restore. This is after hard disable, so EE is clear. */
-
if (unlikely(load_vcpu_state(vcpu, &host_os_sprs)))
msr = mfmsr(); /* MSR may have been updated */
--
2.23.0
