Re: [PATCH 0/3] Resolve vt82c686 and piix4 qemu_irq memory leaks

[Michael S. Tsirkin]

On Mon, Jul 22, 2024 at 10:21:30PM +0000, Bernhard Beschow wrote:
> 
> 
> Am 20. Juli 2024 18:38:42 UTC schrieb "Michael S. Tsirkin" <mst@redhat.com>:
> >On Thu, Jul 04, 2024 at 10:58:51PM +0200, Bernhard Beschow wrote:
> >> This series first turns vt82c686's "INTR" pin into a named GPIO for better
> >> comprehensibility. It then continues fixing qemu_irq memory leaks in 
> >> vt82c686
> >> and piix4 by connecting out IRQs of the south bridges before they get 
> >> realized.
> >> This approach is already used in the pc machines after it had been 
> >> discussed at
> >> KVM forum `23.
> >> 
> >> Observe that out IRQs are callbacks such as an INTR IRQ handler in a CPU 
> >> which a
> >> south bridge wants to trigger. If, as an implementation detail, the south 
> >> bridge
> >> wants to pass this callback to a child device, such as the PIC, then this
> >> callback must be known to the south bridge before it gets realized. 
> >> Otherwise
> >> board code had to wire the PIC device itself, breaking encapsulation. This 
> >> means
> >> that qdev_connect_gpio_out*() has to be called before realize() which this
> >> series implements. Another way to look at it is that callbacks apparently 
> >> are
> >> resouces such as memory regions which are also populated before realize().
> >> 
> >> Please check if above paragraph makes sense.
> >> 
> >> Best regards,
> >> Bernhard
> >
> >
> >Bernhard, do you intend to resolve Zoltan's comments on this
> >patchset?
> 
> Hi Michael,
> 
> I was hoping for some more comments on the last two commits. These resolve 
> various issues in one go, some of which have been addressed in the past. 
> Since this is apparently a new style to handle out-GPIOs, I'd like to get an 
> OK from the community.
> 
> As Zoltan writes the ideal solution might be to qdev'ify the PIC. This is a 
> bigger task which is more than I intended to do in this series.
> 
> Best regards,
> Bernhard


ATM I'm just looking at whether we can fix any bugs for the coming
release.

> >
> >Thanks!
> >
> >
> >> See also:
> >> * 
> >> https://lore.kernel.org/qemu-devel/0FFB5FD2-08CE-4CEC-9001-E7AC24407A44@gmail.
> >> com/
> >> * "Remove intermediate IRQ forwarder" patches in
> >> https://lore.kernel.org/qemu-devel/20230210163744.32182-1-philmd@linaro.org/
> >> 
> >> Testing done:
> >> * Boot amigaone machine into Linux
> >> * Boot pegasos2 machine into MorphOS
> >> * Start fuloong2e machine and check that it doesn't abort
> >> * Boot malta machine with https://people.debian.org/~gio/dqib/
> >> 
> >> Bernhard Beschow (3):
> >>   hw/isa/vt82c686: Turn "intr" irq into a named gpio
> >>   hw/isa/vt82c686: Resolve intermediate IRQ forwarder
> >>   hw/isa/piix: Resolve intermediate IRQ forwarder
> >> 
> >>  hw/isa/piix.c       | 13 ++-----------
> >>  hw/isa/vt82c686.c   | 12 ++----------
> >>  hw/mips/fuloong2e.c |  2 +-
> >>  hw/mips/malta.c     |  4 +---
> >>  hw/ppc/amigaone.c   |  8 ++++----
> >>  hw/ppc/pegasos2.c   |  4 ++--
> >>  6 files changed, 12 insertions(+), 31 deletions(-)
> >> 
> >> -- 
> >> 2.45.2
> >> 
> >