Re: [PATCH] xen: fix condition for enabling the Xen accelerator

["Richard W.M. Jones" <rjones@redhat.com>]

On Sat, Dec 09, 2023 at 03:32:22PM +0100, Paolo Bonzini wrote:
> A misspelled condition in xen_native.h is hiding a bug in the enablement of
> Xen for qemu-system-aarch64.  The bug becomes apparent when building for
> Xen 4.18.
>
> While the i386 emulator provides the xenpv machine type for multiple
> architectures, and therefore can be compiled with Xen enabled even
> when the host is Arm, the opposite is not true: qemu-system-aarch64
> can only be compiled with Xen support enabled when the host is Arm.
>
> Expand the computation of accelerator_targets['CONFIG_XEN'] similar
> to what is already there for KVM, and fix xen_native.h.

Here's a Fedora scratch build with Xen 4.18.0 which includes this patch:

https://koji.fedoraproject.org/koji/taskinfo?taskID=110105806

Rich.

> Cc: Stefano Stabellini <stefano.stabellini@amd.com>
> Cc: Richard W.M. Jones <rjones@redhat.com>
> Cc: Daniel P. Berrangé <berrange@redhat.com>
> Reported-by: Michael Young <m.a.young@durham.ac.uk>
> Supersedes: <277e21fc78b75ec459efc7f5fde628a0222c63b0.1701989261.git.m.a.young@durham.ac.uk>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  include/hw/xen/xen_native.h |  2 +-
>  meson.build                 | 17 ++++++++++-------
>  2 files changed, 11 insertions(+), 8 deletions(-)
> 
> diff --git a/include/hw/xen/xen_native.h b/include/hw/xen/xen_native.h
> index 6f09c48823b..1a5ad693a4d 100644
> --- a/include/hw/xen/xen_native.h
> +++ b/include/hw/xen/xen_native.h
> @@ -532,7 +532,7 @@ static inline int xendevicemodel_set_irq_level(xendevicemodel_handle *dmod,
>  }
>  #endif
>  
> -#if CONFIG_XEN_CTRL_INTERFACE_VERSION <= 41700
> +#if CONFIG_XEN_CTRL_INTERFACE_VERSION < 41700
>  #define GUEST_VIRTIO_MMIO_BASE   xen_mk_ullong(0x02000000)
>  #define GUEST_VIRTIO_MMIO_SIZE   xen_mk_ullong(0x00100000)
>  #define GUEST_VIRTIO_MMIO_SPI_FIRST   33
> diff --git a/meson.build b/meson.build
> index ec01f8b138a..67f4ede8aea 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -123,21 +123,24 @@ if get_option('kvm').allowed() and targetos == 'linux'
>    kvm_targets_c = '"' + '" ,"'.join(kvm_targets) + '"'
>  endif
>  config_host_data.set('CONFIG_KVM_TARGETS', kvm_targets_c)
> -
>  accelerator_targets = { 'CONFIG_KVM': kvm_targets }
>  
> +if cpu in ['x86', 'x86_64']
> +  xen_targets = ['i386-softmmu', 'x86_64-softmmu']
> +elif cpu in ['arm', 'aarch64']
> +  # i386 emulator provides xenpv machine type for multiple architectures
> +  xen_targets = ['i386-softmmu', 'x86_64-softmmu', 'aarch64-softmmu']
> +else
> +  xen_targets = []
> +endif
> +accelerator_targets += { 'CONFIG_XEN': xen_targets }
> +
>  if cpu in ['aarch64']
>    accelerator_targets += {
>      'CONFIG_HVF': ['aarch64-softmmu']
>    }
>  endif
>  
> -if cpu in ['x86', 'x86_64', 'arm', 'aarch64']
> -  # i386 emulator provides xenpv machine type for multiple architectures
> -  accelerator_targets += {
> -    'CONFIG_XEN': ['i386-softmmu', 'x86_64-softmmu', 'aarch64-softmmu'],
> -  }
> -endif
>  if cpu in ['x86', 'x86_64']
>    accelerator_targets += {
>      'CONFIG_HVF': ['x86_64-softmmu'],
> -- 
> 2.43.0

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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