From: Simon Guo <wei.guo.simon@xxxxxxxxx>
The math registers will be saved into vcpu->arch.fp/vr and corresponding
vcpu->arch.fp_tm/vr_tm area.
We flush or giveup the math regs into vcpu->arch.fp/vr before saving
transaction. After transaction is restored, the math regs will be loaded
back into regs.
If there is a FP/VEC/VSX unavailable exception during transaction active
state, the math checkpoint content might be incorrect and we need to do
treclaim./load the correct checkpoint val/trechkpt. sequence to retry the
transaction. That will make our solution complicated. To solve this issue,
we always make the hardware guest MSR math bits (shadow_msr) consistent
with the MSR val which guest sees (kvmppc_get_msr()) when guest msr is
with tm enabled. Then all FP/VEC/VSX unavailable exception can be delivered
to guest and guest handles the exception by itself.
Signed-off-by: Simon Guo <wei.guo.simon@xxxxxxxxx>
---
arch/powerpc/kvm/book3s_pr.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 226bae7..4b81b3c 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -308,6 +308,28 @@ static inline void kvmppc_restore_tm_sprs(struct kvm_vcpu *vcpu)
tm_disable();
}
+/* loadup math bits which is enabled at kvmppc_get_msr() but not enabled at
+ * hardware.
+ */
+static void kvmppc_handle_lost_math_exts(struct kvm_vcpu *vcpu)
+{
+ ulong exit_nr;
+ ulong ext_diff = (kvmppc_get_msr(vcpu) & ~vcpu->arch.guest_owned_ext) &
+ (MSR_FP | MSR_VEC | MSR_VSX);
+
+ if (!ext_diff)
+ return;
+
+ if (ext_diff == MSR_FP)
+ exit_nr = BOOK3S_INTERRUPT_FP_UNAVAIL;
+ else if (ext_diff == MSR_VEC)
+ exit_nr = BOOK3S_INTERRUPT_ALTIVEC;
+ else
+ exit_nr = BOOK3S_INTERRUPT_VSX;
+
+ kvmppc_handle_ext(vcpu, exit_nr, ext_diff);
+}
+
void kvmppc_save_tm_pr(struct kvm_vcpu *vcpu)
{
if (!(MSR_TM_ACTIVE(kvmppc_get_msr(vcpu)))) {
@@ -315,6 +337,8 @@ void kvmppc_save_tm_pr(struct kvm_vcpu *vcpu)
return;
}
+ kvmppc_giveup_ext(vcpu, MSR_VSX);
+
preempt_disable();
_kvmppc_save_tm_pr(vcpu, mfmsr());
preempt_enable();
@@ -324,12 +348,18 @@ void kvmppc_restore_tm_pr(struct kvm_vcpu *vcpu)
{
if (!MSR_TM_ACTIVE(kvmppc_get_msr(vcpu))) {
kvmppc_restore_tm_sprs(vcpu);
+ if (kvmppc_get_msr(vcpu) & MSR_TM)
+ kvmppc_handle_lost_math_exts(vcpu);
return;
}
preempt_disable();
_kvmppc_restore_tm_pr(vcpu, kvmppc_get_msr(vcpu));
preempt_enable();
+
+ if (kvmppc_get_msr(vcpu) & MSR_TM)
+ kvmppc_handle_lost_math_exts(vcpu);
+
}
#endif
@@ -468,6 +498,11 @@ static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr)
/* Preload FPU if it's enabled */
if (kvmppc_get_msr(vcpu) & MSR_FP)
kvmppc_handle_ext(vcpu, BOOK3S_INTERRUPT_FP_UNAVAIL, MSR_FP);
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+ if (kvmppc_get_msr(vcpu) & MSR_TM)
+ kvmppc_handle_lost_math_exts(vcpu);
+#endif
}
void kvmppc_set_pvr_pr(struct kvm_vcpu *vcpu, u32 pvr)
--
1.8.3.1
