From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH 7/8] KVM: assigned dev: Introduce io_device for MSI-X
 MMIO accessing
Date: Wed, 20 Oct 2010 12:33:04 +0200
Message-ID: <20101020103304.GC12878@redhat.com>
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Cc: Sheng Yang <sheng@linux.intel.com>,
	Marcelo Tosatti <mtosatti@redhat.com>, kvm@vger.kernel.org
To: Avi Kivity <avi@redhat.com>
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On Wed, Oct 20, 2010 at 11:46:47AM +0200, Avi Kivity wrote:
> >+		/* Only allow entry modification when entry was masked */
> >+		if (!entry_masked) {
> >+			printk(KERN_WARNING
> >+				"KVM: guest try to write unmasked MSI-X entry. "
> >+				"addr 0x%llx, len %d, val 0x%lx\n",
> >+				addr, len, new_val);
> >+			r = 0;
> 
> What does the spec says about this situation?

That it's not allowed.  However, existing userspace changes entries that
kvm thinks are unmasked, because it does not know how to tell kvm about
mask bits, so we need to keep supporting this.


-- 
MST