Hi,

This is v3 of fixing the sleep-in-atomic problem of the shadow ptdump.
The approach taken this time is simply creating a file for each nested
mmu.

The ptdump files are created alongside the nested mmus in
kvm_vcpu_init_nested(), in a sleepable context, and removed when the VM
is destroyed (kvm_destroy_vm_debugfs(), before the nested mmus are freed
in kvm_destroy_nested()). This allows us to store the kvm_s2_mmu pointers
in the ptdump code, after Marc's nested mmu lifecycle fixes [1].

For the shadow ptdump, for valid nested mmus the first line will show
the nested context's VTTBR and VTCR values, and whether s2 is enabled or
not. The ptdump then follows.

The first patch fixes mmu->pgt accesses after the VM MMU teardown in
ptdump.c, the second patch switches from per nested context ptdumps to
per nested mmu ptdumps.

Tested with CONFIG_PROVE_LOCKING, CONFIG_DEBUG_ATOMIC_SLEEP, and
CONFIG_KASAN.

Series based on kvmarm/fixes.

* Changes from v2 [2]:

  - Changed from creating a file that contains all nested mmus to
    creating one file for each nested mmu.

Thanks!

[1]: https://lore.kernel.org/kvmarm/20260911162203.1919330-1-maz@kernel.org/
[2]: https://lore.kernel.org/kvmarm/20260630121005.1130996-1-weilin.chang@arm.com/

Wei-Lin Chang (2):
  KVM: arm64: ptdump: Check the page tables aren't freed when accessing
  KVM: arm64: ptdump: Fix shadow ptdump sleep-in-atomic-context problem

 arch/arm64/include/asm/kvm_host.h |  4 --
 arch/arm64/include/asm/kvm_mmu.h  |  6 +--
 arch/arm64/kvm/nested.c           |  9 ++--
 arch/arm64/kvm/ptdump.c           | 75 ++++++++++++++++++++-----------
 4 files changed, 54 insertions(+), 40 deletions(-)

-- 
2.43.0

Hi Wei-Lin,

On Thu, Sep 17, 2026 at 12:03:35AM +0100, Wei-Lin Chang wrote:
> Hi,
> 
> This is v3 of fixing the sleep-in-atomic problem of the shadow ptdump.
> The approach taken this time is simply creating a file for each nested
> mmu.
> 
> The ptdump files are created alongside the nested mmus in
> kvm_vcpu_init_nested(), in a sleepable context, and removed when the VM
> is destroyed (kvm_destroy_vm_debugfs(), before the nested mmus are freed
> in kvm_destroy_nested()). This allows us to store the kvm_s2_mmu pointers
> in the ptdump code, after Marc's nested mmu lifecycle fixes [1].
> 
> For the shadow ptdump, for valid nested mmus the first line will show
> the nested context's VTTBR and VTCR values, and whether s2 is enabled or
> not. The ptdump then follows.
> 
> The first patch fixes mmu->pgt accesses after the VM MMU teardown in
> ptdump.c, the second patch switches from per nested context ptdumps to
> per nested mmu ptdumps.
> 
> Tested with CONFIG_PROVE_LOCKING, CONFIG_DEBUG_ATOMIC_SLEEP, and
> CONFIG_KASAN.
> 
> Series based on kvmarm/fixes.
> 
> * Changes from v2 [2]:
> 
>   - Changed from creating a file that contains all nested mmus to
>     creating one file for each nested mmu.

I've booted your kernel built only CONFIG_DEBUG_ATOMIC_SLEEP enabled
mentioned above kernel configs; on Grace CPUs shadow_stage2 test did 
not trigger the sleep in atomic message.

Tested-by: Itaru Kitayama <itaru.kitayama@fujitsu.com>

Thanks,
Itaru.

> 
> Thanks!
> 
> [1]: https://lore.kernel.org/kvmarm/20260911162203.1919330-1-maz@kernel.org/
> [2]: https://lore.kernel.org/kvmarm/20260630121005.1130996-1-weilin.chang@arm.com/
> 
> Wei-Lin Chang (2):
>   KVM: arm64: ptdump: Check the page tables aren't freed when accessing
>   KVM: arm64: ptdump: Fix shadow ptdump sleep-in-atomic-context problem
> 
>  arch/arm64/include/asm/kvm_host.h |  4 --
>  arch/arm64/include/asm/kvm_mmu.h  |  6 +--
>  arch/arm64/kvm/nested.c           |  9 ++--
>  arch/arm64/kvm/ptdump.c           | 75 ++++++++++++++++++++-----------
>  4 files changed, 54 insertions(+), 40 deletions(-)
> 
> -- 
> 2.43.0
>