RE: [PATCH v3 14/21] qemu: Add FakeReboot support for TDX guest
-----Original Message-----
From: Daniel P. Berrangé <berrange(a)redhat.com>
Subject: Re: [PATCH v3 14/21] qemu: Add FakeReboot support for TDX guest
On Mon, Jun 30, 2025 at 02:17:25PM +0800, Zhenzhong Duan wrote:
> Utilize the existing fake reboot mechanism to do reboot for TDX guest.
>
> Different from normal guest, TDX guest doesn't support system_reset,
> so have to kill the old guest and start a new one to simulate the reboot.
>
> Co-developed-by: Chenyi Qiang <chenyi.qiang(a)intel.com>
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan(a)intel.com>
> ---
> src/qemu/qemu_process.c | 80
+++++++++++++++++++++++++++++++++++++++--
> 1 file changed, 77 insertions(+), 3 deletions(-)
One thing I noticed during testing is that when a guest crashes
during boot up eg via a triple-fault, we'll endlessly re-create
QEMU which is quite expensive as memory pages are allocated/deallocated,
and also burn through domain ID values.
Is it because you enabled SEPT #VE? What's your <on_crash> setting?
I'm not sure there's much (anything) we can do about these downsides
though.
About the sept-ve-disable, it's a must for linux kernel, but may be not for others.
Maybe checking "TD misconfiguration: SEPT #VE has to be disabled", but it's
not clean code.
Or maybe document it?
Thanks
Zhenzhong
Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com>
With regards,
Daniel
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