Re: [RFC PATCH] KVM: x86: Allow Qemu/KVM to use PVH entry point

From: Paolo Bonzini <pbonzini@redhat.com>
To: Maran Wilson <maran.wilson@oracle.com>,
	boris.ostrovsky@oracle.com, jgross@suse.com, tglx@linutronix.de,
	mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
	xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
	roger.pau@citrix.com, rkrcmar@redhat.com, JBeulich@suse.com,
	andrew.cooper3@citrix.com, kvm@vger.kernel.org
Subject: Re: [RFC PATCH] KVM: x86: Allow Qemu/KVM to use PVH entry point
Date: Wed, 29 Nov 2017 09:59:14 +0100	[thread overview]
Message-ID: <d94b394d-7acb-0de7-62a7-77ad39fcc268@redhat.com> (raw)
In-Reply-To: <1511897682-32060-1-git-send-email-maran.wilson@oracle.com>

On 28/11/2017 20:34, Maran Wilson wrote:
> For certain applications it is desirable to rapidly boot a KVM virtual
> machine. In cases where legacy hardware and software support within the
> guest is not needed, Qemu should be able to boot directly into the
> uncompressed Linux kernel binary without the need to run firmware.
> 
> There already exists an ABI to allow this for Xen PVH guests and the ABI is
> supported by Linux and FreeBSD:
> 
>    https://xenbits.xen.org/docs/unstable/misc/hvmlite.html
> 
> This PoC patch enables Qemu to use that same entry point for booting KVM
> guests.

Nice!  So QEMU would parse the ELF file just like for multiboot, find
the ELF note, and then prepare an hvmlite boot info struct instead of
the multiboot one?  There would then be a new option ROM, very similar
to multiboot.S.

Thanks,

Paolo