[v1] target/arm: Reduced-IPA space and highmem=off fixes

[PATCH 0/3] target/arm: Reduced-IPA space and highmem=off fixes

Posted by Marc Zyngier 4 years, 5 months ago

With the availability of a fruity range of arm64 systems, it becomes
obvious that QEMU doesn't deal very well with limited IPA ranges when
used as a front-end for KVM.

This short series aims at making usable on such systems:
- the first patch makes the creation of a scratch VM IPA-limit aware
- the second one actually removes the highmem devices from the
computed IPA range when highmem=off
- the last one addresses an imprecision in the documentation for the
highmem option

This has been tested on an M1-based Mac-mini running Linux v5.14-rc6.

Marc Zyngier (3):
  hw/arm/virt: KVM: Probe for KVM_CAP_ARM_VM_IPA_SIZE when creating
    scratch VM
  hw/arm/virt: Honor highmem setting when computing highest_gpa
  docs/system/arm/virt: Fix documentation for the 'highmem' option

 docs/system/arm/virt.rst |  6 +++---
 hw/arm/virt.c            | 10 +++++++---
 target/arm/kvm.c         |  7 ++++++-
 3 files changed, 16 insertions(+), 7 deletions(-)

-- 
2.30.2

Re: [PATCH 0/3] target/arm: Reduced-IPA space and highmem=off fixes

Posted by Marc Zyngier 4 years, 5 months ago

On 2021-08-22 15:44, Marc Zyngier wrote:
> With the availability of a fruity range of arm64 systems, it becomes
> obvious that QEMU doesn't deal very well with limited IPA ranges when
> used as a front-end for KVM.
> 
> This short series aims at making usable on such systems:
> - the first patch makes the creation of a scratch VM IPA-limit aware
> - the second one actually removes the highmem devices from the
> computed IPA range when highmem=off
> - the last one addresses an imprecision in the documentation for the
> highmem option
> 
> This has been tested on an M1-based Mac-mini running Linux v5.14-rc6.

I realise I haven't been very clear in my description of the above.
With this series, using 'highmem=off' results in a usable VM, while
sticking to the default 'highmem=on' still generates an error.

         M.
-- 
Jazz is not dead. It just smells funny...

Re: [PATCH 0/3] target/arm: Reduced-IPA space and highmem=off fixes

Posted by Peter Maydell 4 years, 5 months ago

On Sun, 22 Aug 2021 at 15:45, Marc Zyngier <maz@kernel.org> wrote:
>
> With the availability of a fruity range of arm64 systems, it becomes
> obvious that QEMU doesn't deal very well with limited IPA ranges when
> used as a front-end for KVM.
>
> This short series aims at making usable on such systems:
> - the first patch makes the creation of a scratch VM IPA-limit aware
> - the second one actually removes the highmem devices from the
> computed IPA range when highmem=off
> - the last one addresses an imprecision in the documentation for the
> highmem option
>
> This has been tested on an M1-based Mac-mini running Linux v5.14-rc6.
>
> Marc Zyngier (3):
>   hw/arm/virt: KVM: Probe for KVM_CAP_ARM_VM_IPA_SIZE when creating
>     scratch VM
>   hw/arm/virt: Honor highmem setting when computing highest_gpa
>   docs/system/arm/virt: Fix documentation for the 'highmem' option

I've applied patch 1 to target-arm.next; thanks.

-- PMM