KVM: PPC: Book3S HV: Support reset of secure guest

[linux.git] / arch / powerpc / include / asm / kvm_ppc.h

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 8e8514efb124394813e2a6ef09505f6491e86d76..3d2f871241a8c7bfc7d4cba00f35408ccdfafbcd 100644 (file)
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -271,6 +271,7 @@ struct kvmppc_ops {
                           union kvmppc_one_reg *val);
        void (*vcpu_load)(struct kvm_vcpu *vcpu, int cpu);
        void (*vcpu_put)(struct kvm_vcpu *vcpu);
+       void (*inject_interrupt)(struct kvm_vcpu *vcpu, int vec, u64 srr1_flags);
        void (*set_msr)(struct kvm_vcpu *vcpu, u64 msr);
        int (*vcpu_run)(struct kvm_run *run, struct kvm_vcpu *vcpu);
        struct kvm_vcpu *(*vcpu_create)(struct kvm *kvm, unsigned int id);
@@ -321,6 +322,7 @@ struct kvmppc_ops {
                               int size);
        int (*store_to_eaddr)(struct kvm_vcpu *vcpu, ulong *eaddr, void *ptr,
                              int size);
+       int (*svm_off)(struct kvm *kvm);
 };
 
 extern struct kvmppc_ops *kvmppc_hv_ops;
@@ -452,9 +454,100 @@ static inline u32 kvmppc_get_xics_latch(void)
        return xirr;
 }
 
-static inline void kvmppc_set_host_ipi(int cpu, u8 host_ipi)
+/*
+ * To avoid the need to unnecessarily exit fully to the host kernel, an IPI to
+ * a CPU thread that's running/napping inside of a guest is by default regarded
+ * as a request to wake the CPU (if needed) and continue execution within the
+ * guest, potentially to process new state like externally-generated
+ * interrupts or IPIs sent from within the guest itself (e.g. H_PROD/H_IPI).
+ *
+ * To force an exit to the host kernel, kvmppc_set_host_ipi() must be called
+ * prior to issuing the IPI to set the corresponding 'host_ipi' flag in the
+ * target CPU's PACA. To avoid unnecessary exits to the host, this flag should
+ * be immediately cleared via kvmppc_clear_host_ipi() by the IPI handler on
+ * the receiving side prior to processing the IPI work.
+ *
+ * NOTE:
+ *
+ * We currently issue an smp_mb() at the beginning of kvmppc_set_host_ipi().
+ * This is to guard against sequences such as the following:
+ *
+ *      CPU
+ *        X: smp_muxed_ipi_set_message():
+ *        X:   smp_mb()
+ *        X:   message[RESCHEDULE] = 1
+ *        X: doorbell_global_ipi(42):
+ *        X:   kvmppc_set_host_ipi(42)
+ *        X:   ppc_msgsnd_sync()/smp_mb()
+ *        X:   ppc_msgsnd() -> 42
+ *       42: doorbell_exception(): // from CPU X
+ *       42:   ppc_msgsync()
+ *      105: smp_muxed_ipi_set_message():
+ *      105:   smb_mb()
+ *           // STORE DEFERRED DUE TO RE-ORDERING
+ *    --105:   message[CALL_FUNCTION] = 1
+ *    | 105: doorbell_global_ipi(42):
+ *    | 105:   kvmppc_set_host_ipi(42)
+ *    |  42:   kvmppc_clear_host_ipi(42)
+ *    |  42: smp_ipi_demux_relaxed()
+ *    |  42: // returns to executing guest
+ *    |      // RE-ORDERED STORE COMPLETES
+ *    ->105:   message[CALL_FUNCTION] = 1
+ *      105:   ppc_msgsnd_sync()/smp_mb()
+ *      105:   ppc_msgsnd() -> 42
+ *       42: local_paca->kvm_hstate.host_ipi == 0 // IPI ignored
+ *      105: // hangs waiting on 42 to process messages/call_single_queue
+ *
+ * We also issue an smp_mb() at the end of kvmppc_clear_host_ipi(). This is
+ * to guard against sequences such as the following (as well as to create
+ * a read-side pairing with the barrier in kvmppc_set_host_ipi()):
+ *
+ *      CPU
+ *        X: smp_muxed_ipi_set_message():
+ *        X:   smp_mb()
+ *        X:   message[RESCHEDULE] = 1
+ *        X: doorbell_global_ipi(42):
+ *        X:   kvmppc_set_host_ipi(42)
+ *        X:   ppc_msgsnd_sync()/smp_mb()
+ *        X:   ppc_msgsnd() -> 42
+ *       42: doorbell_exception(): // from CPU X
+ *       42:   ppc_msgsync()
+ *           // STORE DEFERRED DUE TO RE-ORDERING
+ *    -- 42:   kvmppc_clear_host_ipi(42)
+ *    |  42: smp_ipi_demux_relaxed()
+ *    | 105: smp_muxed_ipi_set_message():
+ *    | 105:   smb_mb()
+ *    | 105:   message[CALL_FUNCTION] = 1
+ *    | 105: doorbell_global_ipi(42):
+ *    | 105:   kvmppc_set_host_ipi(42)
+ *    |      // RE-ORDERED STORE COMPLETES
+ *    -> 42:   kvmppc_clear_host_ipi(42)
+ *       42: // returns to executing guest
+ *      105:   ppc_msgsnd_sync()/smp_mb()
+ *      105:   ppc_msgsnd() -> 42
+ *       42: local_paca->kvm_hstate.host_ipi == 0 // IPI ignored
+ *      105: // hangs waiting on 42 to process messages/call_single_queue
+ */
+static inline void kvmppc_set_host_ipi(int cpu)
 {
-       paca_ptrs[cpu]->kvm_hstate.host_ipi = host_ipi;
+       /*
+        * order stores of IPI messages vs. setting of host_ipi flag
+        *
+        * pairs with the barrier in kvmppc_clear_host_ipi()
+        */
+       smp_mb();
+       paca_ptrs[cpu]->kvm_hstate.host_ipi = 1;
+}
+
+static inline void kvmppc_clear_host_ipi(int cpu)
+{
+       paca_ptrs[cpu]->kvm_hstate.host_ipi = 0;
+       /*
+        * order clearing of host_ipi flag vs. processing of IPI messages
+        *
+        * pairs with the barrier in kvmppc_set_host_ipi()
+        */
+       smp_mb();
 }
 
 static inline void kvmppc_fast_vcpu_kick(struct kvm_vcpu *vcpu)
@@ -486,7 +579,10 @@ static inline u32 kvmppc_get_xics_latch(void)
        return 0;
 }
 
-static inline void kvmppc_set_host_ipi(int cpu, u8 host_ipi)
+static inline void kvmppc_set_host_ipi(int cpu)
+{}
+
+static inline void kvmppc_clear_host_ipi(int cpu)
 {}
 
 static inline void kvmppc_fast_vcpu_kick(struct kvm_vcpu *vcpu)