On 19.03.24 15:23, Peter Maydell wrote:
On Tue, 19 Mar 2024 at 09:24, David Hildenbrand <da...@redhat.com> wrote:
I spotted new pause_all_vcpus() / resume_all_vcpus() calls in 
hw/intc/arm_gicv3_kvm.c and
thought they would be the problematic bit.

Yeah, that's going to be problematic. Further note that a lot of code does not 
expect
that the BQL is suddenly dropped.

Agreed; we already have one nasty set of bugs in the framebuffer
devices because a function drops the BQL briefly:
https://lore.kernel.org/qemu-devel/CAFEAcA9odnPo2LPip295Uztri7JfoVnQbkJ=wn+k8dqneb_...@mail.gmail.com/T/#u
so let's avoid introducing any more of a similar kind.

Side note, the pause_all_vcpus()/resume_all_vcpus() calls in
hw/i386/vapic.c are probably a bit suspect for similar reasons.

Exactly my thoughts. But there, it was less clear "why" it is even required. It's only performed for KVM.

Do we also just want to stop KVM threads from executing instructions?, so blocking KVM ioctls might be a reasonable "replacement"? Really not sure.

--
Cheers,

David / dhildenb


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