[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Xen-devel] Why guest is disallowed to change mask bit

  • To: xen-devel@xxxxxxxxxxxxx
  • From: Chien-Hua Yen <chien.yen@xxxxxxxxxx>
  • Date: Fri, 19 Oct 2012 11:45:23 -0700
  • Delivery-date: Fri, 19 Oct 2012 18:45:55 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>


I am curious to know why Xen disallows guest to change the mask bit of MSI-X
vector control as show in the comment out section in msixtbl_write().
Our SR-IOV driver got driver reload failure because it cannot enable interrupt.

     /* 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);
    val |= orig & PCI_MSIX_VECTOR_BITMASK;
    writel(val, virt);
    spin_unlock_irqrestore(&desc->lock, flags);

    r = X86EMUL_OKAY;



Xen-devel mailing list



Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.