From: Paolo Bonzini <pbonzini@redhat.com>
To: Jim Mattson <jmattson@google.com>,
Sean Christopherson <seanjc@google.com>
Cc: Yu Zhang <yu.c.zhang@linux.intel.com>,
Wei Huang <wei.huang2@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
vkuznets@redhat.com, wanpengli@tencent.com, joro@8bytes.org,
tglx@linutronix.de, mingo@redhat.com, bp@alien8.de,
x86@kernel.org, hpa@zytor.com
Subject: Re: [PATCH v2 1/3] KVM: x86: Allow CPU to force vendor-specific TDP level
Date: Tue, 10 Aug 2021 11:23:48 +0200 [thread overview]
Message-ID: <400f8ca7-8f82-308b-3427-b644144cfa5c@redhat.com> (raw)
In-Reply-To: <CALMp9eRfuntBFz=gnsvEuTXAXZorWJFAPq0ZdwZePxxQYGzdQA@mail.gmail.com>
On 09/08/21 23:49, Jim Mattson wrote:
> Doesn't this break legacy type 2 hypervisors that don't know anything
> about 5-level NPT and don't have any control over whether or not the
> host uses 5-level paging?
Yes, where "legacy" probably means "all released versions of all of
them", including KVM. Host support for LA57 was merged in 4.13, while
KVM started supporting 5-level page tables in EPT in 4.14 and even then
just returned PT64_ROOT_LEVEL (i.e. 4) for the maximum NPT level.
So all Linux versions up to 5.13, which has "KVM: x86: Prevent KVM SVM
from loading on kernels with 5-level paging", will break horribly.
Better backport that patch to stable...
Paolo
next prev parent reply other threads:[~2021-08-10 9:24 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-08 19:26 [PATCH v2 0/3] SVM 5-level page table support Wei Huang
2021-08-08 19:26 ` [PATCH v2 1/3] KVM: x86: Allow CPU to force vendor-specific TDP level Wei Huang
2021-08-09 3:58 ` Yu Zhang
2021-08-09 4:11 ` Wei Huang
2021-08-09 4:27 ` Yu Zhang
2021-08-09 4:33 ` Wei Huang
2021-08-09 6:42 ` Yu Zhang
2021-08-09 15:30 ` Sean Christopherson
2021-08-09 21:49 ` Jim Mattson
2021-08-10 9:23 ` Paolo Bonzini [this message]
2021-08-10 7:40 ` Yu Zhang
2021-08-10 9:25 ` Paolo Bonzini
2021-08-10 11:00 ` Yu Zhang
2021-08-10 12:47 ` Paolo Bonzini
2021-08-10 14:37 ` Yu Zhang
2021-08-08 19:26 ` [PATCH v2 2/3] KVM: x86: Handle the case of 5-level shadow page table Wei Huang
2021-08-09 15:17 ` Sean Christopherson
2021-08-09 17:03 ` Wei Huang
2021-08-08 19:26 ` [PATCH v2 3/3] KVM: SVM: Add 5-level page table support for SVM Wei Huang
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