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Re: [PATCH] kvm/i386: Set proper nested state format for SVM
From: |
Tom Lendacky |
Subject: |
Re: [PATCH] kvm/i386: Set proper nested state format for SVM |
Date: |
Mon, 16 Nov 2020 12:25:13 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 |
On 11/16/20 12:09 PM, Paolo Bonzini wrote:
> On 16/11/20 18:02, Tom Lendacky wrote:
>> From: Tom Lendacky<thomas.lendacky@amd.com>
>>
>> Currently, the nested state format is hardcoded to VMX. This will result
>> in kvm_put_nested_state() returning an error because the KVM SVM support
>> checks for the nested state to be KVM_STATE_NESTED_FORMAT_SVM. As a
>> result, kvm_arch_put_registers() errors out early.
>>
>> Update the setting of the format based on the virtualization feature:
>> VMX - KVM_STATE_NESTED_FORMAT_VMX
>> SVM - KVM_STATE_NESTED_FORMAT_SVM
>
> Looks good, but what are the symptoms of this in practice?
I discovered this while testing my SEV-ES patches. When I specified the
'+svm' feature, the new SEV-ES reset address for the APs wasn't getting
set because kvm_arch_put_registers() erred out before it could call
kvm_getput_regs(). This resulted in the guest crashing when OVMF tried to
start the APs.
For a non-SEV-ES guest, I'm not sure if other updates could be missed,
potentially.
Thanks,
Tom
>
> Paolo
>