From: Sean Christopherson <seanjc@google.com>
To: Wei Liu <wei.liu@kernel.org>
Cc: Qiliang Yuan <odys.yuan@gmail.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Thomas Gleixner <tglx@kernel.org>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Vitaly Kuznetsov <vkuznets@redhat.com>,
"K. Y. Srinivasan" <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Dexuan Cui <decui@microsoft.com>, Long Li <longli@microsoft.com>,
linux-hyperv@vger.kernel.org
Subject: Re: [PATCH] KVM: x86: Clear CR3[63:32] on SMM entry from long mode
Date: Mon, 28 Sep 2026 11:19:21 -0700 [thread overview]
Message-ID: <arqvqW7g72AnVsLK@google.com> (raw)
In-Reply-To: <20260928174243.GA3705413@liuwe-devbox-debian-v2.local>
On Mon, Sep 28, 2026, Wei Liu wrote:
> Hi Qiliang
>
> On Mon, Sep 28, 2026 at 03:25:34PM +0800, Qiliang Yuan wrote:
> > +Cc Hyper-V folks and linux-hyperv, since the failure is triggered by
> > Hyper-V's handling of VMRUN for a nested (L1) hypervisor, i.e. KVM
> > running on WSL2.
> >
> > For the Hyper-V side: the VMRUN is rejected when the guest state has
> > CR0.PG=0, EFER.LMA=0 and CR3[63:32] != 0, a combination that bare-metal
> > SVM does not reject. Is that check intentional? If it is not, a
> > Hyper-V fix would help older KVM versions as well; either way the patch
> > avoids creating that state in the first place.
> >
> > The full patch is here:
> > https://lore.kernel.org/r/20260928-kvm-smm-cr3-upper-bits-v1-1-138f52dd531e@gmail.com
>
> Please share the Windows version from `winver`.
>
> My colleague said that it had been fixed. Maybe the change needs to be ported.
Ya, I'd much prefer to get this fixed in Hyper-V. If we need to carry a KVM hack,
then at the very least it should be limited to when KVM detects that it's running
on Hyper-V.
next prev parent reply other threads:[~2026-09-28 18:19 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-28 7:05 Qiliang Yuan
2026-09-28 7:25 ` Qiliang Yuan
2026-09-28 17:42 ` Wei Liu
2026-09-28 18:19 ` Sean Christopherson [this message]
2026-09-29 0:57 ` Qiliang Yuan
2026-09-30 1:42 ` Wei Liu
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