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[Qemu-devel] Re: migrating guest with msi-x interrupts
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: migrating guest with msi-x interrupts |
Date: |
Wed, 26 May 2010 17:02:47 +0300 |
User-agent: |
Mutt/1.5.19 (2009-01-05) |
On Tue, May 25, 2010 at 04:09:13PM -0600, Cam Macdonell wrote:
> Hi,
>
> I'm trying to migrate a guest device with MSI-X interrupts. However,
> the interrupts are not injected into the guest. I've added some
> tracing to msix.c and it seems that the MSI-X vectors are masked when
> the guest is resumed (I'm testing with static migration).
>
> In particular, in msix.c, msix_is_masked(...) is returning true when
> the guest resumes which causes msix_set_pending() to be called instead
> of msix_set_irq().
>
> /* Send an MSI-X message */
> void msix_notify(PCIDevice *dev, unsigned vector)
> {
> uint8_t *table_entry = dev->msix_table_page + vector * MSIX_ENTRY_SIZE;
> uint64_t address;
> uint32_t data;
>
> if (vector >= dev->msix_entries_nr || !dev->msix_entry_used[vector])
> return;
>
> if (msix_is_masked(dev, vector)) {
> msix_set_pending(dev, vector);
> return;
> }
>
> ...
>
> Does migrating a guest device that uses MSI-X require
> msix_load()/save() to be called explicity in a pre/post_save/load
> function?
>
> Any pointers or comments would be helpful,
> Cam
Yes. Look at how virtio does this.
Incidentially, I think reusing virtio for configuration would save
effort, and have other advantages such as making it possible to support
non-pci guests.
--
MST