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Re: [Qemu-devel] [PATCH 0/2] target/i386: kvm: Fix treatment of AMD SVM
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH 0/2] target/i386: kvm: Fix treatment of AMD SVM in nested migration |
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Date: |
Sat, 22 Jun 2019 01:59:17 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 |
On 21/06/19 23:37, Liran Alon wrote:
> However, during discussion made after merge, it was realised that since QEMU
> commit
> 75d373ef9729 ("target-i386: Disable SVM by default in KVM mode"), an AMD vCPU
> that
> is virtualized by KVM doesn't expose SVM by default, even if you use "-cpu
> host".
> Therefore, it is unlikely that vCPU expose SVM CPUID flag when user is not
> running
> an SVM workload inside guest.
libvirt has "host-model" mode, which constructs a "-cpu
model,+feature,+feature" command line option that matches the host as
good as possible. This lets libvirt check migratability while retaining
a lot of the benefits of "-cpu host", and is the default for OpenStack
for example. I need to check if libvirt adds SVM to this configuration,
if it does the QEMU commit you mention is unfortunately not enough.
Paolo