Re: [PATCH] system: Try hardware accelerators (KVM, HVF) before software one (TCG)

[Peter Xu]

On Fri, Jan 03, 2025 at 06:16:38PM +0100, Philippe Mathieu-Daudé wrote:
> On 3/1/25 16:15, Daniel P. Berrangé wrote:
> > On Fri, Jan 03, 2025 at 04:05:58PM +0100, Philippe Mathieu-Daudé wrote:
> > > As Daniel suggested [*]:
> > > 
> > > > We should consider to rank HVF above TCG, on the basis
> > > > that HW acceleration is faster and should provide a
> > > > host<->guest security boundary that we don't claim for TCG
> > > 
> > > [*] https://lore.kernel.org/qemu-devel/Z07YASl2Pd3CPtjE@redhat.com/
> > 
> > Note, my statement above was on the basis that HVF passes all our
> > functional tests, thus indicating a decent level of confidence
> > in the correctness of the HVF impl.
> 
> Indeed, I forgot about that, and only tested in my 'HVF-only'
> directory before posting, but ...
> 
> > If anyone knows any show stopper problems with HVF that would
> > justify blocking its promotion ahead of TCG.... say now.
> 
> ... here we go:
> 
>  3/15 qemu:qtest+qtest-aarch64 / qtest-aarch64/migration-test       ERROR
> 0.88s   killed by signal 11 SIGSEGV

Hmm.. I think migration-test specifies either kvm or tcg in all its tests,
so I don't yet know why this patch can affect it..

migrate_start():
    cmd_source = g_strdup_printf("-accel kvm%s -accel tcg "
                                 "-machine %s,%s "
                                 ...);

May need a closer look on the crashed stack.

-- 
Peter Xu