Re: [PATCH v4 0/4] x86/pvh: fix unbootable VMs again (PVH + KASAN)

[Mauricio Faria de Oliveira <mfo@igalia.com>]

On 2026-05-30 19:04, Borislav Petkov wrote:
> On Sat, May 30, 2026 at 03:25:25PM -0300, Mauricio Faria de Oliveira wrote:
>> In this instance, the use case is to speed up the dev-test cycle when
>> debugging on VMs: PVH allows booting directly from vmlinux, avoiding the
>> need to build/compress and decompress bzImage, while KASAN helps detect
>> issues early.
> 
> Makes sense in itself. And you can't do your use case with KVM? It has to be
> Xen?

It uses KVM, actually. 

IIUIC, the PVH entry point was originally developed for Xen, but later
QEMU support was added for KVM as well.
(found this blog post [1] with a nice summary and links about it.)

>> Briefly, this is a side effect of reusing code from 'boot/string.c'
>> through <asm/string.h>, which introduces additional complications;
>> please see patch 1 for details.
>> 
>> These complications could be avoided by not reusing that code and
>> instead adding slightly duplicated code [1] directly to <asm/string.h>,
>> if that is preferred.
> 
> I'll take a look.

Ok, thanks!

> 
> Thx.

-- 
Mauricio