Revert "interrupts: allow guest to set/clear MSI-X mask bit"

This reverts commit 54a46bce768033b1c36e25eace15f7abde972389.
It's not fully cooked yet.

1 files changed, 14 insertions, 47 deletions

diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c
index e36c1f0d94..0d5ef1b91e 100644
--- a/xen/arch/x86/hvm/vmsi.c
+++ b/xen/arch/x86/hvm/vmsi.c
@@ -169,7 +169,6 @@ struct msixtbl_entry
         uint32_t msi_ad[3];	/* Shadow of address low, high and data */
     } gentries[MAX_MSIX_ACC_ENTRIES];
     struct rcu_head rcu;
-    const struct pirq *pirq;
 };
 
 static DEFINE_RCU_READ_LOCK(msixtbl_rcu_lock);
@@ -255,8 +254,6 @@ static int msixtbl_write(struct vcpu *v, unsigned long address,
     void *virt;
     unsigned int nr_entry, index;
     int r = X86EMUL_UNHANDLEABLE;
-    unsigned long flags, orig;
-    struct irq_desc *desc;
 
     if ( len != 4 || (address & 3) )
         return r;
@@ -286,49 +283,22 @@ static int msixtbl_write(struct vcpu *v, unsigned long address,
     if ( !virt )
         goto out;
 
-    desc = pirq_spin_lock_irq_desc(entry->pirq, &flags);
-    if ( !desc )
-        goto out;
-
-    if ( !desc->msi_desc )
-        goto unlock;
-
+    /* Do not allow the mask bit to be changed. */
+#if 0 /* XXX
+       * As the mask bit is the only defined bit in the word, and as the
+       * host MSI-X code doesn't preserve the other bits anyway, doing
+       * this is pointless. So for now just discard the write (also
+       * saving us from having to determine the matching irq_desc).
+       */
+    spin_lock_irqsave(&desc->lock, flags);
     orig = readl(virt);
-
-    /*
-     * Do not allow guest to modify MSI-X control bit if it is masked
-     * by Xen. We'll only handle the case where Xen thinks that
-     * bit is unmasked, but hardware has silently masked the bit
-     * (in case of SR-IOV VF reset, etc). On the other hand, if Xen
-     * thinks that the bit is masked, but it's really not,
-     * we log a warning.
-     */
-    if ( desc->msi_desc->msi_attrib.masked )
-    {
-        if ( !(orig & PCI_MSIX_VECTOR_BITMASK) )
-            printk(XENLOG_WARNING "MSI-X control bit is unmasked when"
-                   " it is expected to be masked [%04x:%02x:%02x.%01x]\n",
-                   entry->pdev->seg, entry->pdev->bus,
-                   PCI_SLOT(entry->pdev->devfn),
-                   PCI_FUNC(entry->pdev->devfn));
-
-        goto unlock;
-    }
-
-    /*
-     * The mask bit is the only defined bit in the word. But we
-     * ought to preserve the reserved bits. Clearing the reserved
-     * bits can result in undefined behaviour (see PCI Local Bus
-     * Specification revision 2.3).
-     */
-    val &= PCI_MSIX_VECTOR_BITMASK;
-    val |= (orig & ~PCI_MSIX_VECTOR_BITMASK);
+    val &= ~PCI_MSIX_VECTOR_BITMASK;
+    val |= orig & PCI_MSIX_VECTOR_BITMASK;
     writel(val, virt);
-
-unlock:
     spin_unlock_irqrestore(&desc->lock, flags);
-    r = X86EMUL_OKAY;
+#endif
 
+    r = X86EMUL_OKAY;
 out:
     rcu_read_unlock(&msixtbl_rcu_lock);
     return r;
@@ -358,8 +328,7 @@ const struct hvm_mmio_handler msixtbl_mmio_handler = {
 static void add_msixtbl_entry(struct domain *d,
                               struct pci_dev *pdev,
                               uint64_t gtable,
-                              struct msixtbl_entry *entry,
-                              const struct pirq *pirq)
+                              struct msixtbl_entry *entry)
 {
     u32 len;
 
@@ -373,7 +342,6 @@ static void add_msixtbl_entry(struct domain *d,
     entry->table_len = len;
     entry->pdev = pdev;
     entry->gtable = (unsigned long) gtable;
-    entry->pirq = pirq;
 
     list_add_rcu(&entry->list, &d->arch.hvm_domain.msixtbl_list);
 }
@@ -436,10 +404,9 @@ int msixtbl_pt_register(struct domain *d, struct pirq *pirq, uint64_t gtable)
 
     entry = new_entry;
     new_entry = NULL;
-    add_msixtbl_entry(d, pdev, gtable, entry, pirq);
+    add_msixtbl_entry(d, pdev, gtable, entry);
 
 found:
-    ASSERT(entry->pirq == pirq);
     atomic_inc(&entry->refcnt);
     spin_unlock(&d->arch.hvm_domain.msixtbl_list_lock);
     r = 0;