On Fri, Jan 17, 2020 at 01:29:36PM +0000, Daniel P. Berrangé wrote:
> The virConnectGetDomainCapabilities API accepts either a binary path
> to the emulator, or desired guest arch. If guest arch is not given,
> then the host arch is assumed.
>
> In the case where the binary is not given, the code tried to find the
> emulator binary in the existing list of cached emulator capabilities.
> This is not valid since we switched to lazy population of the cache in:
>
> commit 3dd91af01f30c5bda6328454ef49f3afece755d6
> Author: Daniel P. Berrangé <berrange@xxxxxxxxxx>
> Date: Mon Dec 2 13:04:26 2019 +0000
>
> qemu: stop creating capabilities at driver startup
>
> As a result of this change, if there are no persistent guests defined
> using the requested guest architecture, virConnectGetDomainCapabilities
> will fail to find an emulator binary.
>
> The solution is to stop relying on the cached capabilities to find the
> binary and instead use the same logic we use to pick default a binary
> per arch when populating capabilities.
>
> Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
Fixes the problem over here, so:
Tested-by: Richard W.M. Jones <rjones@xxxxxxxxxx>
Thanks,
Rich.
> ---
> src/qemu/qemu_capabilities.c | 42 ++++++++++++++++--------------------
> 1 file changed, 19 insertions(+), 23 deletions(-)
>
> diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
> index 498348ad58..9017e8d920 100644
> --- a/src/qemu/qemu_capabilities.c
> +++ b/src/qemu/qemu_capabilities.c
> @@ -5280,10 +5280,12 @@ virQEMUCapsCacheLookupDefault(virFileCachePtr cache,
> const char **retMachine)
> {
> int virttype = VIR_DOMAIN_VIRT_NONE;
> - int arch = virArchFromHost();
> + virArch hostarch = virArchFromHost();
> + virArch arch = hostarch;
> virDomainVirtType capsType;
> virQEMUCapsPtr qemuCaps = NULL;
> virQEMUCapsPtr ret = NULL;
> + virArch arch_from_caps;
>
> if (virttypeStr &&
> (virttype = virDomainVirtTypeFromString(virttypeStr)) < 0) {
> @@ -5299,31 +5301,25 @@ virQEMUCapsCacheLookupDefault(virFileCachePtr cache,
> goto cleanup;
> }
>
> - if (binary) {
> - virArch arch_from_caps;
> + if (!binary)
> + binary = virQEMUCapsGetDefaultEmulator(hostarch, arch);
>
> - if (!(qemuCaps = virQEMUCapsCacheLookup(cache, binary)))
> - goto cleanup;
> + if (!(qemuCaps = virQEMUCapsCacheLookup(cache, binary)))
> + goto cleanup;
>
> - arch_from_caps = virQEMUCapsGetArch(qemuCaps);
> + arch_from_caps = virQEMUCapsGetArch(qemuCaps);
>
> - if (arch_from_caps != arch &&
> - !((ARCH_IS_X86(arch) && ARCH_IS_X86(arch_from_caps)) ||
> - (ARCH_IS_PPC(arch) && ARCH_IS_PPC(arch_from_caps)) ||
> - (ARCH_IS_ARM(arch) && ARCH_IS_ARM(arch_from_caps)) ||
> - (ARCH_IS_S390(arch) && ARCH_IS_S390(arch_from_caps)))) {
> - virReportError(VIR_ERR_INVALID_ARG,
> - _("architecture from emulator '%s' doesn't "
> - "match given architecture '%s'"),
> - virArchToString(arch_from_caps),
> - virArchToString(arch));
> - goto cleanup;
> - }
> - } else {
> - if (!(qemuCaps = virQEMUCapsCacheLookupByArch(cache, arch)))
> - goto cleanup;
> -
> - binary = virQEMUCapsGetBinary(qemuCaps);
> + if (arch_from_caps != arch &&
> + !((ARCH_IS_X86(arch) && ARCH_IS_X86(arch_from_caps)) ||
> + (ARCH_IS_PPC(arch) && ARCH_IS_PPC(arch_from_caps)) ||
> + (ARCH_IS_ARM(arch) && ARCH_IS_ARM(arch_from_caps)) ||
> + (ARCH_IS_S390(arch) && ARCH_IS_S390(arch_from_caps)))) {
> + virReportError(VIR_ERR_INVALID_ARG,
> + _("architecture from emulator '%s' doesn't "
> + "match given architecture '%s'"),
> + virArchToString(arch_from_caps),
> + virArchToString(arch));
> + goto cleanup;
> }
>
> if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
> --
> 2.23.0
--
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
Read my programming and virtualization blog: http://rwmj.wordpress.com
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine. Supports Linux and Windows.
http://people.redhat.com/~rjones/virt-df/
