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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 14:42:21 +0000	[thread overview]
Message-ID: <Ymv5TR76RNvFBQhz@google.com> (raw)
In-Reply-To: <20e1e7b1-ece7-e9e7-9085-999f7a916ac2@redhat.com>

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.

> but at least I have relied on it to test KVM's MAXPHYADDR=52 cases before
> such hardware existed.  :)

Ah, that's a very good reason to support this for shadow paging.  Maybe throw
something about testing in the changelog?  Without considering the testing angle,
it looks like KVM supports max=52 for !TDP just because it can, because practically
speaking there's unlikely to be a use case for exposing that much memory to a
guest when using shadow paging.

  reply	other threads:[~2022-04-29 14:42 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 [this message]
2022-04-29 14:50         ` Paolo Bonzini
2022-04-29 16:01           ` Sean Christopherson
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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