From: "Michael S. Tsirkin" <mst@redhat.com>
To: Avi Kivity <avi@redhat.com>
Cc: Sheng Yang <sheng@linux.intel.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH 7/8] KVM: assigned dev: Introduce io_device for MSI-X MMIO accessing
Date: Thu, 21 Oct 2010 11:24:59 +0200 [thread overview]
Message-ID: <20101021092459.GA2950@redhat.com> (raw)
In-Reply-To: <4CC00782.8020903@redhat.com>
On Thu, Oct 21, 2010 at 11:27:30AM +0200, Avi Kivity wrote:
> On 10/21/2010 08:46 AM, Sheng Yang wrote:
> >> > + r = -EOPNOTSUPP;
> >>
> >> If the guest assigned the device to another guest, it allows the nested
> >> guest to kill the non-nested guest. Need to exit in a graceful fashion.
> >
> >Don't understand... It wouldn't result in kill but return to QEmu/userspace.
>
> What would qemu do on EOPNOTSUPP? It has no way of knowing that
> this was triggered by an unsupported msix access. What can it do?
>
> Best to just ignore the write.
>
> If you're worried about debugging, we can have a trace_kvm_discard()
> tracepoint that logs the address and a type enum field that explains
> why an access was discarded.
The issue is that the same page is used for mask and entry programming.
> >> > + if (addr % PCI_MSIX_ENTRY_SIZE != PCI_MSIX_ENTRY_VECTOR_CTRL) {
> >> > + /* 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?
> >
> >As Michael pointed out. The spec said the result is "undefined" indeed.
>
> Ok. Then we should silently discard the write instead of allowing
> the guest to flood host dmesg.
>
> >>
> >> > + goto out;
> >> > + }
> >> > + if (new_val& ~1ul) {
> >>
> >> Is there a #define for this bit?
> >
> >Sorry I didn't find it. mask_msi_irq() also use the number 1... Maybe we can add
> >one.
>
> Yes please.
>
>
> --
> error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-10-21 9:31 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-20 8:26 [PATCH 0/8][v2] MSI-X mask emulation support for assigned device Sheng Yang
2010-10-20 8:26 ` [PATCH 1/8] PCI: MSI: Move MSI-X entry definition to pci_regs.h Sheng Yang
2010-10-20 11:07 ` Matthew Wilcox
2010-10-20 8:26 ` [PATCH 2/8] irq: Export irq_to_desc() to modules Sheng Yang
2010-10-20 8:26 ` [PATCH 3/8] KVM: x86: Enable ENABLE_CAP capability for x86 Sheng Yang
2010-10-20 8:26 ` [PATCH 4/8] KVM: Move struct kvm_io_device to kvm_host.h Sheng Yang
2010-10-20 8:26 ` [PATCH 5/8] KVM: Add kvm_get_irq_routing_entry() func Sheng Yang
2010-10-20 8:53 ` Avi Kivity
2010-10-20 8:58 ` Sheng Yang
2010-10-20 9:13 ` Sheng Yang
2010-10-20 9:17 ` Sheng Yang
2010-10-20 9:32 ` Avi Kivity
2010-10-20 8:26 ` [PATCH 6/8] KVM: assigned dev: Preparation for mask support in userspace Sheng Yang
2010-10-20 9:30 ` Avi Kivity
2010-10-22 14:53 ` Marcelo Tosatti
2010-10-24 12:19 ` Sheng Yang
2010-10-24 12:23 ` Michael S. Tsirkin
2010-10-28 8:21 ` Sheng Yang
2010-10-20 8:26 ` [PATCH 7/8] KVM: assigned dev: Introduce io_device for MSI-X MMIO accessing Sheng Yang
2010-10-20 9:46 ` Avi Kivity
2010-10-20 10:33 ` Michael S. Tsirkin
2010-10-21 6:46 ` Sheng Yang
2010-10-21 9:27 ` Avi Kivity
2010-10-21 9:24 ` Michael S. Tsirkin [this message]
2010-10-21 9:47 ` Avi Kivity
2010-10-21 10:51 ` Michael S. Tsirkin
2010-10-20 22:35 ` Michael S. Tsirkin
2010-10-21 7:44 ` Sheng Yang
2010-10-20 8:26 ` [PATCH 8/8] KVM: Emulation MSI-X mask bits for assigned devices Sheng Yang
2010-10-20 9:49 ` Avi Kivity
2010-10-20 22:24 ` Michael S. Tsirkin
2010-10-21 8:30 ` Sheng Yang
2010-10-21 8:39 ` Michael S. Tsirkin
2010-10-22 4:42 ` Sheng Yang
2010-10-22 10:17 ` Michael S. Tsirkin
2010-10-22 13:30 ` Sheng Yang
2010-10-22 14:32 ` Michael S. Tsirkin
2010-10-20 9:51 ` [PATCH 0/8][v2] MSI-X mask emulation support for assigned device Avi Kivity
2010-10-20 10:44 ` Michael S. Tsirkin
2010-10-20 10:59 ` Avi Kivity
2010-10-20 13:43 ` Michael S. Tsirkin
2010-10-20 14:58 ` Alex Williamson
2010-10-20 14:58 ` Michael S. Tsirkin
2010-10-20 15:12 ` Alex Williamson
2010-10-20 15:17 ` Avi Kivity
2010-10-20 15:22 ` Alex Williamson
2010-10-20 15:26 ` Avi Kivity
2010-10-20 15:38 ` Alex Williamson
2010-10-20 14:47 ` Alex Williamson
2010-10-20 14:46 ` Michael S. Tsirkin
2010-10-20 15:07 ` Alex Williamson
2010-10-20 15:13 ` Michael S. Tsirkin
2010-10-20 20:13 ` Alex Williamson
2010-10-20 22:06 ` Michael S. Tsirkin
2010-10-20 15:23 ` Avi Kivity
2010-10-20 15:38 ` Alex Williamson
2010-10-20 15:54 ` Avi Kivity
2010-10-20 15:59 ` Michael S. Tsirkin
2010-10-20 16:13 ` Avi Kivity
2010-10-20 17:11 ` Michael S. Tsirkin
2010-10-20 18:31 ` Alex Williamson
2010-10-21 7:41 ` Sheng Yang
2010-10-20 19:02 ` Marcelo Tosatti
2010-10-21 7:10 ` Sheng Yang
2010-10-21 8:21 ` Michael S. Tsirkin
2010-10-20 22:20 ` Michael S. Tsirkin
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