[PATCH v4 10/29] KVM: PPC: Book3S PR: Sync TM bits to shadow msr for problem state guest

[wei.guo.simon at gmail.com]

From: Simon Guo <wei.guo.simon at gmail.com>

MSR TS bits can be modified with non-privileged instruction like
tbegin./tend.  That means guest can change MSR value "silently" without
notifying host.

It is necessary to sync the TM bits to host so that host can calculate
shadow msr correctly.

note privilege guest will always fail transactions so we only take
care of problem state guest.

The logic is put into kvmppc_copy_from_svcpu() so that
kvmppc_handle_exit_pr() can use correct MSR TM bits even when preemption.

Signed-off-by: Simon Guo <wei.guo.simon at gmail.com>
---
 arch/powerpc/kvm/book3s_pr.c | 73 ++++++++++++++++++++++++++++++--------------
 1 file changed, 50 insertions(+), 23 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index d3237f5..f2ae5a3 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -182,10 +182,36 @@ void kvmppc_copy_to_svcpu(struct kvm_vcpu *vcpu)
 	svcpu_put(svcpu);
 }
 
+static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
+{
+	ulong guest_msr = kvmppc_get_msr(vcpu);
+	ulong smsr = guest_msr;
+
+	/* Guest MSR values */
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_LE |
+		MSR_TM | MSR_TS_MASK;
+#else
+	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_LE;
+#endif
+	/* Process MSR values */
+	smsr |= MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_PR | MSR_EE;
+	/* External providers the guest reserved */
+	smsr |= (guest_msr & vcpu->arch.guest_owned_ext);
+	/* 64-bit Process MSR values */
+#ifdef CONFIG_PPC_BOOK3S_64
+	smsr |= MSR_ISF | MSR_HV;
+#endif
+	vcpu->arch.shadow_msr = smsr;
+}
+
 /* Copy data touched by real-mode code from shadow vcpu back to vcpu */
 void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu)
 {
 	struct kvmppc_book3s_shadow_vcpu *svcpu = svcpu_get(vcpu);
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	ulong old_msr;
+#endif
 
 	/*
 	 * Maybe we were already preempted and synced the svcpu from
@@ -228,6 +254,30 @@ void kvmppc_copy_from_svcpu(struct kvm_vcpu *vcpu)
 	to_book3s(vcpu)->vtb += get_vtb() - vcpu->arch.entry_vtb;
 	if (cpu_has_feature(CPU_FTR_ARCH_207S))
 		vcpu->arch.ic += mfspr(SPRN_IC) - vcpu->arch.entry_ic;
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+	/*
+	 * Unlike other MSR bits, MSR[TS]bits can be changed at guest without
+	 * notifying host:
+	 *  modified by unprivileged instructions like "tbegin"/"tend"/
+	 * "tresume"/"tsuspend" in PR KVM guest.
+	 *
+	 * It is necessary to sync here to calculate a correct shadow_msr.
+	 *
+	 * privileged guest's tbegin will be failed at present. So we
+	 * only take care of problem state guest.
+	 */
+	old_msr = kvmppc_get_msr(vcpu);
+	if (unlikely((old_msr & MSR_PR) &&
+		(vcpu->arch.shadow_srr1 & (MSR_TS_MASK)) !=
+				(old_msr & (MSR_TS_MASK)))) {
+		old_msr &= ~(MSR_TS_MASK);
+		old_msr |= (vcpu->arch.shadow_srr1 & (MSR_TS_MASK));
+		kvmppc_set_msr_fast(vcpu, old_msr);
+		kvmppc_recalc_shadow_msr(vcpu);
+	}
+#endif
+
 	svcpu->in_use = false;
 
 out:
@@ -306,29 +356,6 @@ static void kvm_set_spte_hva_pr(struct kvm *kvm, unsigned long hva, pte_t pte)
 
 /*****************************************/
 
-static void kvmppc_recalc_shadow_msr(struct kvm_vcpu *vcpu)
-{
-	ulong guest_msr = kvmppc_get_msr(vcpu);
-	ulong smsr = guest_msr;
-
-	/* Guest MSR values */
-#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
-	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_LE |
-		MSR_TM | MSR_TS_MASK;
-#else
-	smsr &= MSR_FE0 | MSR_FE1 | MSR_SF | MSR_SE | MSR_BE | MSR_LE;
-#endif
-	/* Process MSR values */
-	smsr |= MSR_ME | MSR_RI | MSR_IR | MSR_DR | MSR_PR | MSR_EE;
-	/* External providers the guest reserved */
-	smsr |= (guest_msr & vcpu->arch.guest_owned_ext);
-	/* 64-bit Process MSR values */
-#ifdef CONFIG_PPC_BOOK3S_64
-	smsr |= MSR_ISF | MSR_HV;
-#endif
-	vcpu->arch.shadow_msr = smsr;
-}
-
 static void kvmppc_set_msr_pr(struct kvm_vcpu *vcpu, u64 msr)
 {
 	ulong old_msr = kvmppc_get_msr(vcpu);
-- 
1.8.3.1