[Xen-devel] [PATCH RFC v1 47/74] x86/guest: fix upcall vector setup

[Wei Liu <wei.liu2@xxxxxxxxxx>]

From: Roger Pau Monne <roger.pau@xxxxxxxxxx>

Instead of forcing no pending event on the vCPU, just mask all event
channels when setting up the BSP and further patches will unmask them
as event channels are being setup.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
To be squashed with "x86/guest: enable event channels upcalls"
---
 xen/arch/x86/guest/xen.c | 61 +++++++++++-------------------------------------
 1 file changed, 14 insertions(+), 47 deletions(-)

diff --git a/xen/arch/x86/guest/xen.c b/xen/arch/x86/guest/xen.c
index 0f2c5d7413..a95c36017f 100644
--- a/xen/arch/x86/guest/xen.c
+++ b/xen/arch/x86/guest/xen.c
@@ -33,7 +33,6 @@
 bool xen_guest;
 
 static uint32_t xen_cpuid_base;
-static uint8_t evtchn_upcall_vector;
 extern char hypercall_page[];
 static struct rangeset *mem;
 
@@ -86,6 +85,7 @@ static void map_shared_info(void)
         .domid = DOMID_SELF,
         .space = XENMAPSPACE_shared_info,
     };
+    unsigned int i;
 
     if ( hypervisor_alloc_unused_page(&mfn) )
         panic("unable to reserve shared info memory page");
@@ -95,6 +95,10 @@ static void map_shared_info(void)
         panic("Failed to map shared_info page");
 
     set_fixmap(FIX_XEN_SHARED_INFO, mfn_x(mfn) << PAGE_SHIFT);
+
+    /* Mask all upcalls */
+    for ( i = 0; i < ARRAY_SIZE(XEN_shared_info->evtchn_mask); i++ )
+        xchg(&XEN_shared_info->evtchn_mask[i], ~0ul);
 }
 
 static void set_vcpu_id(void)
@@ -124,58 +128,21 @@ static void xen_evtchn_upcall(struct cpu_user_regs *regs)
     ack_APIC_irq();
 }
 
-static void ap_setup_event_channels(bool clear)
+static void init_evtchn(void)
 {
-    unsigned int i, cpu = this_cpu(vcpu_id);
-    struct vcpu_info *vcpu_info = &XEN_shared_info->vcpu_info[cpu];
+    unsigned int vcpu = this_cpu(vcpu_id);
+    static uint8_t evtchn_upcall_vector;
     int rc;
 
-    ASSERT(evtchn_upcall_vector);
-    ASSERT(cpu < ARRAY_SIZE(XEN_shared_info->vcpu_info));
+    if ( !evtchn_upcall_vector )
+        alloc_direct_apic_vector(&evtchn_upcall_vector, xen_evtchn_upcall);
 
-    if ( !clear )
-    {
-        /*
-         * This is necessary to ensure that a CPU will be interrupted in case
-         * of an event channel notification.
-         */
-        ASSERT(vcpu_info->evtchn_upcall_pending == 0);
-        ASSERT(vcpu_info->evtchn_pending_sel == 0);
-    }
+    ASSERT(evtchn_upcall_vector);
+    ASSERT(vcpu < ARRAY_SIZE(XEN_shared_info->vcpu_info));
 
-    rc = xen_hypercall_set_evtchn_upcall_vector(cpu, evtchn_upcall_vector);
+    rc = xen_hypercall_set_evtchn_upcall_vector(vcpu, evtchn_upcall_vector);
     if ( rc )
         panic("Unable to set evtchn upcall vector: %d", rc);
-
-    if ( clear )
-    {
-        /*
-         * Clear any pending upcall bits. This makes us effectively ignore any
-         * previous upcalls which might be suboptimal.
-         */
-        vcpu_info->evtchn_upcall_pending = 0;
-        xchg(&vcpu_info->evtchn_pending_sel, 0);
-
-        /*
-         * evtchn_pending can be cleared only on the boot CPU because it's
-         * located in a shared structure.
-         */
-        for ( i = 0; i < 8; i++ )
-            xchg(&XEN_shared_info->evtchn_pending[i], 0);
-    }
-}
-
-static void __init init_evtchn(void)
-{
-    unsigned int i;
-
-    alloc_direct_apic_vector(&evtchn_upcall_vector, xen_evtchn_upcall);
-
-    /* Mask all upcalls */
-    for ( i = 0; i < 8; i++ )
-        xchg(&XEN_shared_info->evtchn_mask[i], ~0ul);
-
-    ap_setup_event_channels(true);
 }
 
 static void __init init_memmap(void)
@@ -215,7 +182,7 @@ void __init hypervisor_setup(void)
 void hypervisor_ap_setup(void)
 {
     set_vcpu_id();
-    ap_setup_event_channels(false);
+    init_evtchn();
 }
 
 int hypervisor_alloc_unused_page(mfn_t *mfn)
-- 
2.11.0


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