linux-kernel - Re: [PATCH] kvm: x86: fix RSM when PCID is non-zero

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Message-ID: <7fb80c8b-fa21-fc68-a8b8-1cff68d8df3f@redhat.com>
Date:   Thu, 21 Dec 2017 17:53:47 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     "Christopherson, Sean J" <sean.j.christopherson@...el.com>,
        Andy Lutomirski <luto@...nel.org>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        kvm list <kvm@...r.kernel.org>,
        Laszlo Ersek <lersek@...hat.com>
Subject: Re: [PATCH] kvm: x86: fix RSM when PCID is non-zero

On 21/12/2017 17:37, Christopherson, Sean J wrote:
>> Out of curiosity, has anyone ever tested RSM returning to PAE mode?  I
>> *think* it's supposed to restore the PDPTR registers directly rather
>> than reloading them from the memory pointed to by CR3, and it doesn't
>> look like the new or old code does it.
> Yes, PDPTRs are saved/loaded to/from SMRAM, at least on Intel hardware.

KVM follows the AMD manual, since it's got a more complete description
of SMRAM, and it doesn't show the PDPTRs (nor any reserved area large
enough to hold them).

Thanks,

Paolo