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From: Sean Christopherson <seanjc@google.com>
To: Yosry Ahmed <yosry@kernel.org>
Cc: Jim Mattson <jmattson@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	kvm@vger.kernel.org,  linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/6] KVM: SVM: Use maxphyaddr in emulator RAX check for VMRUN/VMLOAD/VMSAVE
Date: Fri, 6 Mar 2026 16:32:32 -0800	[thread overview]
Message-ID: <aatyIPwz9ePKdzJx@google.com> (raw)
In-Reply-To: <CAO9r8zOK5+xmkf3FsWRz2wHcUCN30GJ9kfZx-K7DAa1HNGhRVA@mail.gmail.com>

On Fri, Mar 06, 2026, Yosry Ahmed wrote:
> > > Right, but I am trying to have the #GP check for VMLOAD/VMSAVE behave
> > > consistently with vls=1, whether it's done by the hardware or the
> > > emulator.
> >
> > Consistency should not be an issue, since VLS cannot be enabled when
> > the MAXPHYADDRs differ. VLS doesn't work in that scenario.
> 
> Why? It's only broken if VMLOAD/VMSAVE is executed with a GPA that
> exceeds the guest's MAXPHYADDR, but not the host's, right? So only
> broken if the guest is misbehaving.
> 
> Taking a step back, I am not disagreeing that VLS should not be used
> with different MAXPHYADDRs, I am just saying it might be.

KVM straight up doesn't support that (see my other reply).

> All that being said, I am fine with using cpuid_maxphyaddr(vcpu)
> instead of kvm_host.maxphyaddr. Will wait for Sean's feedback to
> figure out if a new version is needed.

LOL, Jim and I are of one mind when it comes to guest.MAXPHYADDR.

  parent reply	other threads:[~2026-03-07  0:32 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-06 21:08 [PATCH v2 0/6] KVM: nSVM: Fix vmcb12 mapping failure handling Yosry Ahmed
2026-03-06 21:08 ` [PATCH v2 1/6] KVM: SVM: Use maxphyaddr in emulator RAX check for VMRUN/VMLOAD/VMSAVE Yosry Ahmed
2026-03-06 22:27   ` Jim Mattson
2026-03-06 22:37     ` Yosry Ahmed
2026-03-06 23:12       ` Jim Mattson
2026-03-06 23:20         ` Yosry Ahmed
2026-03-06 23:45           ` Jim Mattson
2026-03-07  0:32           ` Sean Christopherson [this message]
2026-03-11 18:31             ` Yosry Ahmed
2026-03-11 20:07               ` Yosry Ahmed
2026-03-11 20:39                 ` Sean Christopherson
2026-03-11 20:50                   ` Yosry Ahmed
2026-03-11 23:01                     ` Sean Christopherson
2026-03-11 23:22                       ` Yosry Ahmed
2026-03-12  1:27                         ` Yosry Ahmed
2026-03-12  1:38                           ` Sean Christopherson
2026-03-12 15:50                       ` Yosry Ahmed
2026-03-12 15:54                         ` Sean Christopherson
2026-03-12 16:19                           ` Yosry Ahmed
2026-03-07  0:28         ` Sean Christopherson
2026-03-07  0:31           ` Yosry Ahmed
2026-03-06 21:08 ` [PATCH v2 2/6] KVM: nSVM: Simplify error handling of nested_svm_copy_vmcb12_to_cache() Yosry Ahmed
2026-03-12 18:13   ` Sean Christopherson
2026-03-12 21:01     ` Yosry Ahmed
2026-03-06 21:08 ` [PATCH v2 3/6] KVM: SVM: Treat mapping failures equally in VMLOAD/VMSAVE emulation Yosry Ahmed
2026-03-06 21:08 ` [PATCH v2 4/6] KVM: nSVM: Fail emulation of VMRUN/VMLOAD/VMSAVE if mapping vmcb12 fails Yosry Ahmed
2026-03-07  1:09   ` Yosry Ahmed
2026-03-09 13:56     ` Yosry Ahmed
2026-03-06 21:08 ` [PATCH v2 5/6] KVM: selftests: Rework svm_nested_invalid_vmcb12_gpa Yosry Ahmed
2026-03-06 21:09 ` [PATCH v2 6/6] KVM: selftests: Drop 'invalid' from svm_nested_invalid_vmcb12_gpa's name Yosry Ahmed
2026-04-03 15:13 ` [PATCH v2 0/6] KVM: nSVM: Fix vmcb12 mapping failure handling Sean Christopherson

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