From: Sean Christopherson <seanjc@google.com>
To: Binbin Wu <binbin.wu@linux.intel.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
"Peter Gonda" <pgonda@google.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Tom Lendacky" <thomas.lendacky@amd.com>,
"Jürgen Groß" <jgross@suse.com>,
"Korakit Seemakhupt" <korakit@google.com>,
"Jianxiong Gao" <jxgao@google.com>,
"Nikolay Borisov" <nik.borisov@suse.com>
Subject: Re: [PATCH v2] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
Date: Mon, 8 Sep 2025 13:09:54 -0700 [thread overview]
Message-ID: <aL84ElCqFIRF05JM@google.com> (raw)
In-Reply-To: <28d5fb22-5b0c-4bf9-85c7-1986d9cc005b@linux.intel.com>
On Thu, Aug 28, 2025, Binbin Wu wrote:
> > Note #2, relying on guest firmware to handle this scenario, e.g. by setting
> > virtual MTRRs and then consuming them in Linux, is not a viable option, as
> > the virtual MTRR state is managed by the untrusted hypervisor, and because
> > OVMF at least has stopped programming virtual MTRRs when running as a TDX
> > guest.
>
> Not sure if it needs to mention that with this option, Linux kernel will set
> CR0.CD=1 when programming MTRRs, which will trigger unexpected #VE in TDX guest.
I don't think it's worth bringing up, because that is a very solvable problem,
and orthogonal to the issues with using the untrusted hypervisor to store/track
the virtual MTRR values.
next prev parent reply other threads:[~2025-09-08 20:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-08-28 0:52 [PATCH v2] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP Sean Christopherson
2025-08-28 1:53 ` Binbin Wu
2025-09-08 20:09 ` Sean Christopherson [this message]
2025-09-02 20:40 ` Korakit Seemakhupt
2025-09-16 0:25 ` Sean Christopherson
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