linux-kernel - Re: [PATCH 4/7] kvm: vmx: Set IBPB when running a different VCPU

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Date:   Tue, 9 Jan 2018 09:33:49 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Jim Mattson <jmattson@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>, aliguori@...zon.com,
        Tom Lendacky <thomas.lendacky@....com>, dwmw@...zon.co.uk,
        bp@...en8.de, Tim Chen <tim.c.chen@...ux.intel.com>
Subject: Re: [PATCH 4/7] kvm: vmx: Set IBPB when running a different VCPU

On 08/01/2018 20:36, Jim Mattson wrote:
> Shouldn't there be an IBPB on *any* context switch away from a VCPU
> thread, even if it is to a non-VCPU thread?

Yes, but that's the task of patches to the generic Linux context
switching code.  As mentioned in the cover letter, this isn't yet a full
solution---just the KVM bits, which is what Radim and I have full
control on.  Hence the hacks with cpuid in local bools.

Paolo