linux-kernel - Re: [PATCH v2] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP

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Message-ID: <175798202141.623675.2546293939402072087.b4-ty@google.com>
Date: Mon, 15 Sep 2025 17:25:35 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Peter Gonda <pgonda@...gle.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, 
	Tom Lendacky <thomas.lendacky@....com>, 
	"Jürgen Groß" <jgross@...e.com>, Korakit Seemakhupt <korakit@...gle.com>, Jianxiong Gao <jxgao@...gle.com>, 
	Nikolay Borisov <nik.borisov@...e.com>, Binbin Wu <binbin.wu@...ux.intel.com>
Subject: Re: [PATCH v2] x86/kvm: Force legacy PCI hole to UC when overriding
 MTRRs for TDX/SNP

On Wed, 27 Aug 2025 17:52:49 -0700, Sean Christopherson wrote:
> When running as an SNP or TDX guest under KVM, force the legacy PCI hole,
> i.e. memory between Top of Lower Usable DRAM and 4GiB, to be mapped as UC
> via a forced variable MTRR range.
> 
> In most KVM-based setups, legacy devices such as the HPET and TPM are
> enumerated via ACPI.  ACPI enumeration includes a Memory32Fixed entry, and
> optionally a SystemMemory descriptor for an OperationRegion, e.g. if the
> device needs to be accessed via a Control Method.
> 
> [...]

Applied to kvm-x86 guest, thanks!

[1/1] x86/kvm: Force legacy PCI hole to UC when overriding MTRRs for TDX/SNP
      https://github.com/kvm-x86/linux/commit/0dccbc75e18d

--
https://github.com/kvm-x86/linux/tree/next