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Re: [PATCH 0/2] exclude hyperv synic sections from vhost
From: |
Roman Kagan |
Subject: |
Re: [PATCH 0/2] exclude hyperv synic sections from vhost |
Date: |
Thu, 9 Jan 2020 11:53:56 +0000 |
On Wed, Jan 08, 2020 at 01:53:51PM +0000, Dr. David Alan Gilbert (git) wrote:
> Hyperv's synic (that we emulate) is a feature that allows the guest
> to place some magic (4k) pages of RAM anywhere it likes in GPA.
> This confuses vhost's RAM section merging when these pages
> land over the top of hugepages.
>
> Since they're not normal RAM, and they shouldn't have vhost DMAing
> into them, exclude them from the vhost set.
But they *are* normal RAM. If the guest driver sets up the device to
DMA to a SynIC page so be it, and the guest deserves what it gets.
> I do that by marking them as device-ram and then excluding device-ram
> from vhost.
>
> bz: https://bugzilla.redhat.com/show_bug.cgi?id=1779041
I was pointed a while back by Vitaly at
https://bugs.launchpad.net/qemu/+bug/1811533 which appeared to be the
same issue, but failed to reproduce the problem. Can you please provide
some more detail as to how it's triggered?
Thanks,
Roman.
- Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device, (continued)
Re: [PATCH 2/2] hyperv/synic: Allocate as ram_device, Roman Kagan, 2020/01/09
Re: [PATCH 0/2] exclude hyperv synic sections from vhost, Vitaly Kuznetsov, 2020/01/08
Re: [PATCH 0/2] exclude hyperv synic sections from vhost, Jason Wang, 2020/01/08
Re: [PATCH 0/2] exclude hyperv synic sections from vhost,
Roman Kagan <=