linux-kernel - Re: [PATCH v2 1/2] KVM: SVM: Move asid to vcpu

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Message-Id: <20201129094109.32520-1-Ashish.Kalra@amd.com>
Date:   Sun, 29 Nov 2020 09:41:09 +0000
From:   Ashish Kalra <Ashish.Kalra@....com>
To:     pbonzini@...hat.com
Cc:     cavery@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, mlevitsk@...hat.com,
        vkuznets@...hat.com, wei.huang2@....com, thomas.lendacky@....com,
        brijesh.singh@....com, jon.grimm@....com
Subject: Re: [PATCH v2 1/2] KVM: SVM: Move asid to vcpu_svm

From: Ashish Kalra <ashish.kalra@....com>

This patch breaks SEV guests. 

The patch stores current ASID in struct vcpu_svm and only moves it to VMCB in
svm_vcpu_run(), but by doing so, the ASID allocated for SEV guests and setup 
in vmcb->control.asid by pre_sev_run() gets over-written by this ASID
stored in struct vcpu_svm and hence, VMRUN fails as SEV guest is bound/activated
on a different ASID then the one overwritten in vmcb->control.asid at VMRUN. 

For example, asid#1 was activated for SEV guest and then vmcb->control.asid is
overwritten with asid#0 (svm->asid) as part of this patch in svm_vcpu_run() and
hence VMRUN fails.