On Thu, May 03, 2018 at 04:08:17PM +1000, Paul Mackerras wrote:

On Wed, Apr 25, 2018 at 07:54:41PM +0800, wei.guo.simon@gmail.com wrote:

quoted

From: Simon Guo <redacted>

Currently HV will save math regs(FP/VEC/VSX) when trap into host. But
PR KVM will only save math regs when qemu task switch out of CPU.

To emulate FP/VEC/VSX load, PR KVM need to flush math regs firstly and
then be able to update saved VCPU FPR/VEC/VSX area reasonably.

This patch adds the giveup_ext() to KVM ops (an empty one for HV KVM)
and kvmppc_complete_mmio_load() can invoke that hook to flush math
regs accordingly.

Math regs flush is also necessary for STORE, which will be covered
in later patch within this patch series.

Signed-off-by: Simon Guo <redacted>

I don't see where you have provided a function for Book E.

I would suggest you only set the function pointer to non-NULL when the
function is actually needed, i.e. for PR KVM.

Got it.

It seems to me that this means that emulation of FP/VMX/VSX loads is
currently broken for PR KVM for the case where kvm_io_bus_read() is
able to supply the data, and the emulation of FP/VMX/VSX stores is
broken for PR KVM for all cases.  Do you agree?

Yes. I think so.

quoted

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 5b875ba..7eb5507 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c

@@ -2084,6 +2084,10 @@ static int kvmhv_set_smt_mode(struct kvm *kvm, unsigned long smt_mode,
 	return err;
 }
 
+static void kvmhv_giveup_ext(struct kvm_vcpu *vcpu, ulong msr)
+{
+}
+
 static void unpin_vpa(struct kvm *kvm, struct kvmppc_vpa *vpa)
 {
 	if (vpa->pinned_addr)

@@ -4398,6 +4402,7 @@ static int kvmhv_configure_mmu(struct kvm *kvm, struct kvm_ppc_mmuv3_cfg *cfg)
 	.configure_mmu = kvmhv_configure_mmu,
 	.get_rmmu_info = kvmhv_get_rmmu_info,
 	.set_smt_mode = kvmhv_set_smt_mode,
+	.giveup_ext = kvmhv_giveup_ext,
 };
 
 static int kvm_init_subcore_bitmap(void)

I think HV KVM could leave this pointer as NULL, and then...

ok.

quoted

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 17f0315..e724601 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c

@@ -1061,6 +1061,9 @@ static void kvmppc_complete_mmio_load(struct kvm_vcpu *vcpu,
 		kvmppc_set_gpr(vcpu, vcpu->arch.io_gpr, gpr);
 		break;
 	case KVM_MMIO_REG_FPR:
+		if (!is_kvmppc_hv_enabled(vcpu->kvm))
+			vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_FP);
+

This could become
		if (vcpu->kvm->arch.kvm_ops->giveup_ext)
			vcpu->kvm->arch.kvm_ops->giveup_ext(vcpu, MSR_FP);

and you wouldn't need to fix Book E explicitly.

Yes

Paul.

Thanks,
- Simon