[Xen-changelog] [xen master] y86/vmx: dump PIR and vIRR before ASSERT()

[patchbot@xxxxxxx]

commit 997382b7713d2250910c927d6cc31f152908bf3e
Author:     Chao Gao <chao.gao@xxxxxxxxx>
AuthorDate: Mon Feb 13 15:19:42 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Feb 13 15:19:42 2017 +0100

    y86/vmx: dump PIR and vIRR before ASSERT()
    
    Commit c7bdecae42 ("x86/apicv: fix RTC periodic timer and apicv issue") has
    added a assertion that intack.vector is the highest priority vector. But
    according to the osstest, the assertion failed sometimes. More discussion 
can
    be found in the thread
    
(https://lists.xenproject.org/archives/html/xen-devel/2017-01/msg01019.html).
    
    The assertion failure is hard to reproduce. In order to root cause issue, 
this
    patch is to add logs to dump PIR and vIRR when failure takes place. It 
should
    be reverted once the root cause is found.
    
    Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/intr.c | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)

diff --git a/xen/arch/x86/hvm/vmx/intr.c b/xen/arch/x86/hvm/vmx/intr.c
index 24e4505..1e17c4e 100644
--- a/xen/arch/x86/hvm/vmx/intr.c
+++ b/xen/arch/x86/hvm/vmx/intr.c
@@ -23,6 +23,7 @@
 #include <xen/errno.h>
 #include <xen/trace.h>
 #include <xen/event.h>
+#include <asm/apicdef.h>
 #include <asm/current.h>
 #include <asm/cpufeature.h>
 #include <asm/processor.h>
@@ -318,6 +319,45 @@ void vmx_intr_assist(void)
         */
         if ( pt_vector != -1 )
         {
+            /*
+             * We assert that intack.vector is the highest priority vector for
+             * only an interrupt from vlapic can reach this point and the
+             * highest vector is chosen in hvm_vcpu_has_pending_irq().
+             * But, in fact, the assertion failed sometimes. It is suspected
+             * that PIR is not synced to vIRR which makes pt_vector is left in
+             * PIR. In order to verify this suspicion, dump some information
+             * when the assertion fails.
+             */
+            if ( unlikely(intack.vector < pt_vector) )
+            {
+                const struct vlapic *vlapic;
+                const struct pi_desc *pi_desc;
+                const uint32_t *word;
+                unsigned int i;
+
+                printk(XENLOG_ERR "%pv: intack: %02x:%u pt: %02x\n",
+                       current, intack.source, intack.vector, pt_vector);
+
+                vlapic = vcpu_vlapic(v);
+                if ( vlapic && vlapic->regs->data )
+                {
+                    word = (const void *)&vlapic->regs->data[APIC_IRR];
+                    printk(XENLOG_ERR "vIRR:");
+                    for ( i = NR_VECTORS / 32; i-- ; )
+                        printk(" %08x", word[i*4]);
+                    printk("\n");
+                }
+
+                pi_desc = &v->arch.hvm_vmx.pi_desc;
+                if ( pi_desc && pi_desc->pir )
+                {
+                    word = (const void *)&pi_desc->pir;
+                    printk(XENLOG_ERR " PIR:");
+                    for ( i = NR_VECTORS / 32; i-- ; )
+                        printk(" %08x", word[i]);
+                    printk("\n");
+                }
+            }
             ASSERT(intack.vector >= pt_vector);
             vmx_set_eoi_exit_bitmap(v, intack.vector);
         }
--
generated by git-patchbot for /home/xen/git/xen.git#master

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