From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Maxim Levitsky <mlevitsk@redhat.com>,
Ben Gardon <bgardon@google.com>,
David Matlack <dmatlack@google.com>
Subject: Re: [PATCH] KVM: x86/mmu: Do not create SPTEs for GFNs that exceed host.MAXPHYADDR
Date: Fri, 29 Apr 2022 16:01:55 +0000 [thread overview]
Message-ID: <YmwL87h6klEC4UKV@google.com> (raw)
In-Reply-To: <e5864cb4-cce8-bd32-04b0-ecb60c058d0b@redhat.com>
On Fri, Apr 29, 2022, Paolo Bonzini wrote:
> On 4/29/22 16:42, Sean Christopherson wrote:
> > On Fri, Apr 29, 2022, Paolo Bonzini wrote:
> > > On 4/29/22 16:24, Sean Christopherson wrote:
> > > > I don't love the divergent memslot behavior, but it's technically correct, so I
> > > > can't really argue. Do we want to "officially" document the memslot behavior?
> > > >
> > >
> > > I don't know what you mean by officially document,
> >
> > Something in kvm/api.rst under KVM_SET_USER_MEMORY_REGION.
>
> Not sure if the API documentation is the best place because userspace does
> not know whether shadow paging is on (except indirectly through other
> capabilities, perhaps)?
Hrm, true, it's not like the userspace VMM can rewrite itself at runtime.
> It could even be programmatic, such as returning 52 for CPUID[0x80000008].
> A nested KVM on L1 would not be able to use the #PF(RSVD) trick to detect
> MMIO faults. That's not a big price to pay, however I'm not sure it's a
> good idea in general...
Agreed, messing with CPUID is likely to end in tears.
next prev parent reply other threads:[~2022-04-29 16:02 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-28 23:34 [PATCH] KVM: x86/mmu: Do not create SPTEs for GFNs that exceed host.MAXPHYADDR Sean Christopherson
2022-04-29 10:36 ` Paolo Bonzini
2022-04-29 14:24 ` Sean Christopherson
2022-04-29 14:37 ` Paolo Bonzini
2022-04-29 14:42 ` Sean Christopherson
2022-04-29 14:50 ` Paolo Bonzini
2022-04-29 16:01 ` Sean Christopherson [this message]
2022-05-01 14:28 ` Maxim Levitsky
2022-05-01 14:32 ` Maxim Levitsky
2022-05-02 7:59 ` Maxim Levitsky
2022-05-02 8:56 ` Maxim Levitsky
2022-05-02 16:51 ` Sean Christopherson
2022-05-03 9:12 ` Maxim Levitsky
2022-05-03 15:12 ` Maxim Levitsky
2022-05-03 20:30 ` Sean Christopherson
2022-05-04 12:08 ` Maxim Levitsky
2022-05-04 14:47 ` Sean Christopherson
2022-05-04 19:11 ` Paolo Bonzini
2022-05-02 11:12 ` Kai Huang
2022-05-02 11:52 ` Paolo Bonzini
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