From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Jim Mattson <jmattson@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Joerg Roedel <joro@8bytes.org>, kvm list <kvm@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Oliver Upton <oupton@google.com>, Peter Shier <pshier@google.com>
Subject: Re: [PATCH] KVM: x86: Don't attempt to load PDPTRs when 64-bit mode is enabled
Date: Tue, 14 Jul 2020 11:58:54 -0700 [thread overview]
Message-ID: <20200714185853.GC14404@linux.intel.com> (raw)
In-Reply-To: <CALMp9eQ1-6GEiSh55-NXgjuq3EOwP9VWNMeriH_J64p9JMjN0g@mail.gmail.com>
On Tue, Jul 14, 2020 at 11:55:45AM -0700, Jim Mattson wrote:
> On Mon, Jul 13, 2020 at 6:57 PM Sean Christopherson
> <sean.j.christopherson@intel.com> wrote:
> >
> > Don't attempt to load PDPTRs if EFER.LME=1, i.e. if 64-bit mode is
> > enabled. A recent change to reload the PDTPRs when CR0.CD or CR0.NW is
> > toggled botched the EFER.LME handling and sends KVM down the PDTPR path
> > when is_paging() is true, i.e. when the guest toggles CD/NW in 64-bit
> > mode.
>
> Oops!
>
> I don't think "is_paging()" is relevant here, so much as "EFER.LME=1."
> As you note below, KVM *should* go down the PDPTR path when
> is_paging() is true and EFER.LME=0.
It's relevant for the EFER.LME=1 case as it's used to detect CR0.PG 0->1.
Though maybe we're in violent agreement?
next prev parent reply other threads:[~2020-07-14 19:02 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-14 1:57 [PATCH] KVM: x86: Don't attempt to load PDPTRs when 64-bit mode is enabled Sean Christopherson
2020-07-14 12:00 ` Vitaly Kuznetsov
2020-07-14 13:21 ` Sean Christopherson
2020-07-14 14:11 ` Vitaly Kuznetsov
2020-07-14 18:55 ` Jim Mattson
2020-07-14 18:58 ` Sean Christopherson [this message]
2020-07-14 19:02 ` Jim Mattson
2020-08-04 18:41 ` Sean Christopherson
2020-08-04 18:46 ` Jim Mattson
2020-08-04 19:09 ` Sean Christopherson
2020-08-05 7:04 ` Maxim Levitsky
2020-08-06 21:32 ` Jim Mattson
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