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[Xen-devel] [PATCH v3 1/2] xen/x86: cleanup unused NMI/MCE code



pv_raise_interrupt() is only called for NMIs these days, so the MCE
specific part can be removed. Rename pv_raise_interrupt() to
pv_raise_nmi() and NMI_MCE_SOFTIRQ to NMI_SOFTIRQ.

Additionally there is no need to pin the vcpu the NMI is delivered
to, that is a leftover of (already removed) MCE handling. So remove
the pinning, too. Note that pinning was introduced by commit 355b0469a8
adding MCE support (with NMI support existing already). MCE using
that pinning was removed with commit 3a91769d6e again without cleaning
up the code.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/arch/x86/pv/traps.c        | 93 ++++++++++--------------------------------
 xen/arch/x86/traps.c           | 10 +----
 xen/common/domain.c            |  3 --
 xen/include/asm-x86/pv/traps.h |  6 +--
 xen/include/asm-x86/softirq.h  |  2 +-
 xen/include/xen/sched.h        |  2 -
 6 files changed, 25 insertions(+), 91 deletions(-)

diff --git a/xen/arch/x86/pv/traps.c b/xen/arch/x86/pv/traps.c
index 1740784ff2..aa26e7171a 100644
--- a/xen/arch/x86/pv/traps.c
+++ b/xen/arch/x86/pv/traps.c
@@ -136,47 +136,20 @@ bool set_guest_nmi_trapbounce(void)
     return !null_trap_bounce(curr, tb);
 }
 
-struct softirq_trap {
-    struct domain *domain;   /* domain to inject trap */
-    struct vcpu *vcpu;       /* vcpu to inject trap */
-    unsigned int processor;  /* physical cpu to inject trap */
-};
+static DEFINE_PER_CPU(struct vcpu *, softirq_nmi_vcpu);
 
-static DEFINE_PER_CPU(struct softirq_trap, softirq_trap);
-
-static void nmi_mce_softirq(void)
+static void nmi_softirq(void)
 {
-    unsigned int cpu = smp_processor_id();
-    struct softirq_trap *st = &per_cpu(softirq_trap, cpu);
+    struct vcpu **v_ptr = &this_cpu(softirq_nmi_vcpu);
 
-    BUG_ON(st->vcpu == NULL);
+    BUG_ON(*v_ptr == NULL);
 
     /*
-     * Set the tmp value unconditionally, so that the check in the iret
-     * hypercall works.
-     */
-    cpumask_copy(st->vcpu->cpu_hard_affinity_tmp,
-                 st->vcpu->cpu_hard_affinity);
-
-    if ( (cpu != st->processor) ||
-         (st->processor != st->vcpu->processor) )
-    {
-
-        /*
-         * We are on a different physical cpu.  Make sure to wakeup the vcpu on
-         * the specified processor.
-         */
-        vcpu_set_hard_affinity(st->vcpu, cpumask_of(st->processor));
-
-        /* Affinity is restored in the iret hypercall. */
-    }
-
-    /*
-     * Only used to defer wakeup of domain/vcpu to a safe (non-NMI/MCE)
+     * Only used to defer wakeup of domain/vcpu to a safe (non-NMI)
      * context.
      */
-    vcpu_kick(st->vcpu);
-    st->vcpu = NULL;
+    vcpu_kick(*v_ptr);
+    *v_ptr = NULL;
 }
 
 void __init pv_trap_init(void)
@@ -189,50 +162,26 @@ void __init pv_trap_init(void)
     _set_gate(idt_table + LEGACY_SYSCALL_VECTOR, SYS_DESC_trap_gate, 3,
               &int80_direct_trap);
 
-    open_softirq(NMI_MCE_SOFTIRQ, nmi_mce_softirq);
+    open_softirq(NMI_SOFTIRQ, nmi_softirq);
 }
 
-int pv_raise_interrupt(struct vcpu *v, uint8_t vector)
+/*
+ * Deliver NMI to PV guest. Return 0 on success.
+ * Called in NMI context, so no use of printk().
+ */
+int pv_raise_nmi(struct vcpu *v)
 {
-    struct softirq_trap *st = &per_cpu(softirq_trap, smp_processor_id());
+    struct vcpu **v_ptr = &per_cpu(softirq_nmi_vcpu, smp_processor_id());
 
-    switch ( vector )
+    if ( cmpxchgptr(v_ptr, NULL, v) )
+        return -EBUSY;
+    if ( !test_and_set_bool(v->nmi_pending) )
     {
-    case TRAP_nmi:
-        if ( cmpxchgptr(&st->vcpu, NULL, v) )
-            return -EBUSY;
-        if ( !test_and_set_bool(v->nmi_pending) )
-        {
-            st->domain = v->domain;
-            st->processor = v->processor;
-
-            /* Not safe to wake up a vcpu here */
-            raise_softirq(NMI_MCE_SOFTIRQ);
-            return 0;
-        }
-        st->vcpu = NULL;
-        break;
-
-    case TRAP_machine_check:
-        if ( cmpxchgptr(&st->vcpu, NULL, v) )
-            return -EBUSY;
-
-        /*
-         * We are called by the machine check (exception or polling) handlers
-         * on the physical CPU that reported a machine check error.
-         */
-        if ( !test_and_set_bool(v->mce_pending) )
-        {
-            st->domain = v->domain;
-            st->processor = v->processor;
-
-            /* not safe to wake up a vcpu here */
-            raise_softirq(NMI_MCE_SOFTIRQ);
-            return 0;
-        }
-        st->vcpu = NULL;
-        break;
+        /* Not safe to wake up a vcpu here */
+        raise_softirq(NMI_SOFTIRQ);
+        return 0;
     }
+    *v_ptr = NULL;
 
     /* Delivery failed */
     return -EIO;
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 25b4b47e5e..08d7edc568 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1600,14 +1600,6 @@ void async_exception_cleanup(struct vcpu *curr)
     if ( !curr->async_exception_mask )
         return;
 
-    /* Restore affinity.  */
-    if ( !cpumask_empty(curr->cpu_hard_affinity_tmp) &&
-         !cpumask_equal(curr->cpu_hard_affinity_tmp, curr->cpu_hard_affinity) )
-    {
-        vcpu_set_hard_affinity(curr, curr->cpu_hard_affinity_tmp);
-        cpumask_clear(curr->cpu_hard_affinity_tmp);
-    }
-
     if ( !(curr->async_exception_mask & (curr->async_exception_mask - 1)) )
         trap = __scanbit(curr->async_exception_mask, VCPU_TRAP_NONE);
     else
@@ -1634,7 +1626,7 @@ static void nmi_hwdom_report(unsigned int reason_idx)
 
     set_bit(reason_idx, nmi_reason(d));
 
-    pv_raise_interrupt(d->vcpu[0], TRAP_nmi);
+    pv_raise_nmi(d->vcpu[0]);
 }
 
 static void pci_serr_error(const struct cpu_user_regs *regs)
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 55aa759b75..bc56a51815 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -133,7 +133,6 @@ static void vcpu_info_reset(struct vcpu *v)
 static void vcpu_destroy(struct vcpu *v)
 {
     free_cpumask_var(v->cpu_hard_affinity);
-    free_cpumask_var(v->cpu_hard_affinity_tmp);
     free_cpumask_var(v->cpu_hard_affinity_saved);
     free_cpumask_var(v->cpu_soft_affinity);
 
@@ -161,7 +160,6 @@ struct vcpu *vcpu_create(
     grant_table_init_vcpu(v);
 
     if ( !zalloc_cpumask_var(&v->cpu_hard_affinity) ||
-         !zalloc_cpumask_var(&v->cpu_hard_affinity_tmp) ||
          !zalloc_cpumask_var(&v->cpu_hard_affinity_saved) ||
          !zalloc_cpumask_var(&v->cpu_soft_affinity) )
         goto fail;
@@ -1269,7 +1267,6 @@ int vcpu_reset(struct vcpu *v)
     v->async_exception_mask = 0;
     memset(v->async_exception_state, 0, sizeof(v->async_exception_state));
 #endif
-    cpumask_clear(v->cpu_hard_affinity_tmp);
     clear_bit(_VPF_blocked, &v->pause_flags);
     clear_bit(_VPF_in_reset, &v->pause_flags);
 
diff --git a/xen/include/asm-x86/pv/traps.h b/xen/include/asm-x86/pv/traps.h
index fcc75f5e9a..855203c4e2 100644
--- a/xen/include/asm-x86/pv/traps.h
+++ b/xen/include/asm-x86/pv/traps.h
@@ -27,8 +27,7 @@
 
 void pv_trap_init(void);
 
-/* Deliver interrupt to PV guest. Return 0 on success. */
-int pv_raise_interrupt(struct vcpu *v, uint8_t vector);
+int pv_raise_nmi(struct vcpu *v);
 
 int pv_emulate_privileged_op(struct cpu_user_regs *regs);
 void pv_emulate_gate_op(struct cpu_user_regs *regs);
@@ -46,8 +45,7 @@ static inline bool pv_trap_callback_registered(const struct 
vcpu *v,
 
 static inline void pv_trap_init(void) {}
 
-/* Deliver interrupt to PV guest. Return 0 on success. */
-static inline int pv_raise_interrupt(struct vcpu *v, uint8_t vector) { return 
-EOPNOTSUPP; }
+static inline int pv_raise_nmi(struct vcpu *v) { return -EOPNOTSUPP; }
 
 static inline int pv_emulate_privileged_op(struct cpu_user_regs *regs) { 
return 0; }
 static inline void pv_emulate_gate_op(struct cpu_user_regs *regs) {}
diff --git a/xen/include/asm-x86/softirq.h b/xen/include/asm-x86/softirq.h
index 5c1a7db566..0b7a77f11f 100644
--- a/xen/include/asm-x86/softirq.h
+++ b/xen/include/asm-x86/softirq.h
@@ -1,7 +1,7 @@
 #ifndef __ASM_SOFTIRQ_H__
 #define __ASM_SOFTIRQ_H__
 
-#define NMI_MCE_SOFTIRQ        (NR_COMMON_SOFTIRQS + 0)
+#define NMI_SOFTIRQ            (NR_COMMON_SOFTIRQS + 0)
 #define TIME_CALIBRATE_SOFTIRQ (NR_COMMON_SOFTIRQS + 1)
 #define VCPU_KICK_SOFTIRQ      (NR_COMMON_SOFTIRQS + 2)
 
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index b40c8fd138..c197e93d73 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -245,8 +245,6 @@ struct vcpu
 
     /* Bitmask of CPUs on which this VCPU may run. */
     cpumask_var_t    cpu_hard_affinity;
-    /* Used to change affinity temporarily. */
-    cpumask_var_t    cpu_hard_affinity_tmp;
     /* Used to restore affinity across S3. */
     cpumask_var_t    cpu_hard_affinity_saved;
 
-- 
2.16.4


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